1
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Balucani N, Brann M, Brünken S, Ceccarelli C, Cordiner M, Crump EM, Douglas KM, Fleisher AJ, Flint A, Fulker J, Garrod RT, Gudipati MS, Gupta D, Halpern J, Heard DE, Herbst E, Hockey EK, Huang KY, Jacovella U, Kamp I, Lemmens AK, Madhusudhan N, McCoustra MRS, McGuire B, Meijer A, Puzzarini C, Rap DB, Sims IR, Stockett MH, Sturm A, Suits AG, van Dishoeck EF, Viti S, Walker N, Widicus Weaver S, Wiesenfeld L, Wilkins OH. Laboratory astrochemistry of the gas phase: general discussion. Faraday Discuss 2023; 245:391-445. [PMID: 37671500 DOI: 10.1039/d3fd90025h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
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2
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Navarro Navarrete JE, Bull JN, Cederquist H, Indrajith S, Ji M, Schmidt HT, Zettergren H, Zhu B, Stockett MH. Experimental radiative cooling rates of a polycyclic aromatic hydrocarbon cation. Faraday Discuss 2023; 245:352-367. [PMID: 37317671 DOI: 10.1039/d3fd00005b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Several small Polycyclic Aromatic Hydrocarbons (PAHs) have been identified recently in the Taurus Molecular Cloud (TMC-1) using radio telescope observations. Reproducing the observed abundances of these molecules has been a challenge for astrochemical models. Rapid radiative cooling of PAHs by Recurrent Fluorescence (RF), the emission of optical photons from thermally populated electronically excited states, has been shown to efficiently stabilize small PAHs following ionization, augmenting their resilience in astronomical environments and helping to rationalize their observed high abundances. Here, we use a novel method to experimentally determine the radiative cooling rate of the cation of 1-cyanonaphthalene (C10H7CN, 1-CNN), the neutral species of which has been identified in TMC-1. Laser-induced dissociation rates and kinetic energy release distributions of 1-CNN cations isolated in a cryogenic electrostatic ion-beam storage ring are analysed to track the time evolution of the vibrational energy distribution of the initially hot ion ensemble as it cools. The measured cooling rate is in good agreement with the previously calculated RF rate coefficient. Improved measurements and models of the RF mechanism are needed to interpret astronomical observations and refine predictions of the stabilities of interstellar PAHs.
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Affiliation(s)
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich, UK
| | | | | | - MingChao Ji
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | | | | | - Boxing Zhu
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | - Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden.
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3
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Najeeb PK, Stockett MH, Anderson EK, Kristiansson MK, Reinhed P, Simonsson A, Rosén S, Thomas RD, Chartkunchand KC, Gnaser H, Golser R, Hanstorp D, Larson Å, Cederquist H, Schmidt HT, Zettergren H. Stability and Cooling of the C_{7}^{2-} Dianion. Phys Rev Lett 2023; 131:113003. [PMID: 37774298 DOI: 10.1103/physrevlett.131.113003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/26/2023] [Accepted: 08/12/2023] [Indexed: 10/01/2023]
Abstract
We have studied the stability of the smallest long-lived all carbon molecular dianion (C_{7}^{2-}) in new time domains and with a single ion at a time using a cryogenic electrostatic ion-beam storage ring. We observe spontaneous electron emission from internally excited dianions on millisecond timescales and monitor the survival of single colder C_{7}^{2-} molecules on much longer timescales. We find that their intrinsic lifetime exceeds several minutes-6 orders of magnitude longer than established from earlier experiments on C_{7}^{2-}. This is consistent with our calculations of vertical electron detachment energies predicting one inherently stable isomer and one isomer which is stable or effectively stable behind a large Coulomb barrier for C_{7}^{2-}→C_{7}^{-}+e^{-} separation.
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Affiliation(s)
- P K Najeeb
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - E K Anderson
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - M K Kristiansson
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - P Reinhed
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - A Simonsson
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - S Rosén
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - R D Thomas
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - K C Chartkunchand
- AMO Physics Laboratory, RIKEN Advanced Science Institute, Saitama 351-0198, Japan
| | - H Gnaser
- Institute for Isotope Physics, University of Vienna, Vienna A-1090, Austria
| | - R Golser
- Institute for Isotope Physics, University of Vienna, Vienna A-1090, Austria
| | - D Hanstorp
- Department of Physics, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - Å Larson
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - H T Schmidt
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden
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4
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Ashworth EK, Dezalay J, Ryan CRM, Ieritano C, Hopkins WS, Chambrier I, Cammidge AN, Stockett MH, Noble JA, Bull JN. Protomers of the green and cyan fluorescent protein chromophores investigated using action spectroscopy. Phys Chem Chem Phys 2023. [PMID: 37465988 DOI: 10.1039/d3cp02661b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
The photophysics of biochromophore ions often depends on the isomeric or protomeric distribution, yet this distribution, and the individual isomer contributions to an action spectrum, can be difficult to quantify. Here, we use two separate photodissociation action spectroscopy instruments to record electronic spectra for protonated forms of the green (pHBDI+) and cyan (Cyan+) fluorescent protein chromophores. One instrument allows for cryogenic (T = 40 ± 10 K) cooling of the ions, while the other offers the ability to perform protomer-selective photodissociation spectroscopy. We show that both chromophores are generated as two protomers when using electrospray ionisation, and that the protomers have partially overlapping absorption profiles associated with the S1 ← S0 transition. The action spectra for both species span the 340-460 nm range, although the spectral onset for the pHBDI+ protomer with the proton residing on the carbonyl oxygen is red-shifted by ≈40 nm relative to the lower-energy imine protomer. Similarly, the imine and carbonyl protomers are the lowest energy forms of Cyan+, with the main band for the carbonyl protomer red-shifted by ≈60 nm relative to the lower-energy imine protomer. The present strategy for investigating protomers can be applied to a wide range of other biochromophore ions.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Jordan Dezalay
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - Christian Ieritano
- Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo N2L 3G1, Canada
| | - Isabelle Chambrier
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Andrew N Cammidge
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
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5
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Bull JN, Bolognesi P, Anstöter CS, Ashworth EK, Navarro Navarrete JE, Zhu B, Richter R, Pal N, Chiarinelli J, Avaldi L, Zettergren H, Stockett MH. Autoionization from the plasmon resonance in isolated 1-cyanonaphthalene. J Chem Phys 2023; 158:241101. [PMID: 37347125 DOI: 10.1063/5.0153058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 06/05/2023] [Indexed: 06/23/2023] Open
Abstract
Polycyclic aromatic hydrocarbons have widely been conjectured to be ubiquitous in space, as supported by the recent discovery of two isomers of cyanonaphthalene, indene, and 2-cyanoindene in the Taurus molecular cloud-1 using radioastronomy. Here, the photoionization dynamics of 1-cyanonaphthalene (1-CNN) are investigated using synchrotron radiation over the hν = 9.0-19.5 eV range, revealing that prompt autoionization from the plasmon resonance dominates the photophysics for hν = 11.5-16.0 eV. Minimal photo-induced dissociation, whether originating from an excited state impulsive bond rupture or through internal conversion followed by a statistical bond cleavage process, occurs over the microsecond timescale (as limited by the experimental setup). The direct photoionization cross section and photoelectron angular distributions are simulated using an ezDyson model combining Dyson orbitals with Coulomb wave photoejection. When considering these data in conjunction with recent radiative cooling measurements on 1-CNN+, which showed that cations formed with up to 5 eV of internal energy efficiently stabilize through recurrent fluorescence, we conclude that the organic backbone of 1-CNN is resilient to photodestruction by VUV and soft XUV radiation. These dynamics may prove to be a common feature for the survival of small polycyclic aromatic hydrocarbons in space, provided that the cations have a suitable electronic structure to support recurrent fluorescence.
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Affiliation(s)
- James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
- Centre for Photonics and Quantum Science, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Paola Bolognesi
- CNR-Istituto di Struttura della Materia, Area della Ricerca di Roma 1, Rome, Italy
| | - Cate S Anstöter
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | | | - Boxing Zhu
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | - Nitish Pal
- Elettra Sincrotrone Trieste, Trieste, Italy
| | - Jacopo Chiarinelli
- CNR-Istituto di Struttura della Materia, Area della Ricerca di Roma 1, Rome, Italy
| | - Lorenzo Avaldi
- CNR-Istituto di Struttura della Materia, Area della Ricerca di Roma 1, Rome, Italy
| | | | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
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Barreiro-Lage D, Chiarinelli J, Bolognesi P, Richter R, Zettergren H, Stockett MH, Díaz-Tendero S, Avaldi L. Photofragmentation specificity of photoionized cyclic amino acids (diketopiperazines) as precursors of peptide building blocks. Phys Chem Chem Phys 2023. [PMID: 37166113 DOI: 10.1039/d3cp00608e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The photoionisation and photofragmentation of the two cyclic dipetides cyclo(alanyl-glycine) cGA and cyclo(glycyl-glycine) cGG, have been studied combining experiments and simulations. State selected fragments from the ionized molecules are detected using photo-electron photo-ion coincidence (PEPICO) measurements and specific fragmentation paths are identified and characterized via the use of ion-neutral coincidence maps. The simulations, performed using Quantum Chemistry methods, allow us to infer the fragmentation mechanisms of the ionized and excited molecules. We show that ring opening is followed by emission of the neutral fragments CO and HNCO. In the case of cGG the emission of neutral CO leads to a metastable structure that breaks producing small cationic fragments. The studied cyclic dipeptides evolve under ionizing radiation generating different small aziridin moieties and oxazolidinones. These two species are key reactants to elongate producing peptide chains. The corresponding mechanisms have been computed and show that the reaction requires very low energy and may occur in the presence of ionizing radiation.
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Affiliation(s)
- Darío Barreiro-Lage
- Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - Jacopo Chiarinelli
- Institute of Structure of Matter-CNR (ISM-CNR), 00015 Monterotondo, Italy.
| | - Paola Bolognesi
- Institute of Structure of Matter-CNR (ISM-CNR), 00015 Monterotondo, Italy.
| | - Robert Richter
- Elettra Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | | | - Mark H Stockett
- Department of Physics, Stockholm University, Se-10691 Stockholm, Sweden
| | - Sergio Díaz-Tendero
- Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Institute for Advanced Research in Chemical Science (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Lorenzo Avaldi
- Institute of Structure of Matter-CNR (ISM-CNR), 00015 Monterotondo, Italy.
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Lee JWL, Stockett MH, Ashworth EK, Navarro Navarrete JE, Gougoula E, Garg D, Ji M, Zhu B, Indrajith S, Zettergren H, Schmidt HT, Bull JN. Cooling dynamics of energized naphthalene and azulene radical cations. J Chem Phys 2023; 158:2887564. [PMID: 37125715 DOI: 10.1063/5.0147456] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/12/2023] [Indexed: 05/02/2023] Open
Abstract
Naphthalene and azulene are isomeric polycyclic aromatic hydrocarbons (PAHs) and are topical in the context of astrochemistry due to the recent discovery of substituted naphthalenes in the Taurus Molecular Cloud-1 (TMC-1). Here, the thermal- and photo-induced isomerization, dissociation, and radiative cooling dynamics of energized (vibrationally hot) naphthalene (Np+) and azulene (Az+) radical cations, occurring over the microsecond to seconds timescale, are investigated using a cryogenic electrostatic ion storage ring, affording "molecular cloud in a box" conditions. Measurement of the cooling dynamics and kinetic energy release distributions for neutrals formed through dissociation, until several seconds after hot ion formation, are consistent with the establishment of a rapid (sub-microsecond) Np+ ⇌ Az+ quasi-equilibrium. Consequently, dissociation by C2H2-elimination proceeds predominantly through common Az+ decomposition pathways. Simulation of the isomerization, dissociation, recurrent fluorescence, and infrared cooling dynamics using a coupled master equation combined with high-level potential energy surface calculations [CCSD(T)/cc-pVTZ], reproduce the trends in the measurements. The data show that radiative cooling via recurrent fluorescence, predominately through the Np+ D0 ← D2 transition, efficiently quenches dissociation for vibrational energies up to ≈1 eV above dissociation thresholds. Our measurements support the suggestion that small cations, such as naphthalene, may be more abundant in space than previously thought. The strategy presented in this work could be extended to fingerprint the cooling dynamics of other PAH ions for which isomerization is predicted to precede dissociation.
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Affiliation(s)
- Jason W L Lee
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | | | - Eva Gougoula
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Diksha Garg
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - MingChao Ji
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Boxing Zhu
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | | | - Henning T Schmidt
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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Bernard J, Ji M, Indrajith S, Stockett MH, Navarro Navarrete JE, Kono N, Cederquist H, Martin S, Schmidt HT, Zettergren H. Efficient radiative cooling of tetracene cations C 18H 12+: absolute recurrent fluorescence rates as a function of internal energy. Phys Chem Chem Phys 2023; 25:10726-10740. [PMID: 37000595 DOI: 10.1039/d3cp00424d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023]
Abstract
We have measured recurrent fluorescence (RF) cooling rates of internally hot tetracene cations, C18H12+, as functions of their storage times and internal energies in two different electrostatic ion-beam storage rings - the cryogenic ring DESIREE with a circumference of 8.6 meters in Stockholm and the much smaller room temperature ring Mini-Ring in Lyon, which has a circumference of 0.71 meters. The RF rates were measured to be as high as 150 to 1000 s-1 for internal energies in the 7 to 9.4 eV energy range, where we have probed the time evolution of the internal energy distribution with nanosecond laser pulses with a 1 kHz repetition rate. These RF rates are found to be significantly higher than those of previously investigated smaller PAHs such as e.g. anthracene and naphthalene, for which the lowest non-forbidden electronic excited state, the D2 state, is populated with a smaller probability by inverse internal conversion. Furthermore, the D2-D0 transition rate is smaller for these smaller molecules than for tetracene. The complementary features of the two storage rings allow for RF rate measurements in a broader internal energy range than has been possible before. The smaller sampling period of about 6 μs in Mini-Ring is ideal to study the cooling dynamics of the hotter ions that decay fast, whereas DESIREE with a sampling period of about 60 μs is better suited to study the colder ions that decay on longer timescales ranging up to hundreds of milliseconds. The excellent agreement between the two series of measurements in the region where they overlap demonstrates the complementarity of the two electrostatic ion-beam storage rings.
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Affiliation(s)
- Jérôme Bernard
- Institut Lumière Matière (iLM), UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
| | - MingChao Ji
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - Suvasthika Indrajith
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - Mark H Stockett
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - José E Navarro Navarrete
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - Naoko Kono
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - Henrik Cederquist
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - Serge Martin
- Institut Lumière Matière (iLM), UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne, France.
| | - Henning T Schmidt
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
| | - Henning Zettergren
- Department of Physics, Stockholm University, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden
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9
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Stockett MH, Bull JN, Cederquist H, Indrajith S, Ji M, Navarro Navarrete JE, Schmidt HT, Zettergren H, Zhu B. Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds. Nat Commun 2023; 14:395. [PMID: 36693859 PMCID: PMC9873784 DOI: 10.1038/s41467-023-36092-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/13/2023] [Indexed: 01/25/2023] Open
Abstract
After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and kinetic energy release distributions produced from an ensemble of internally excited 1-CNN+ studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence - radiative relaxation via thermally populated electronic excited states - efficiently stabilizes 1-CNN+, owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.
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Affiliation(s)
- Mark H. Stockett
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
| | - James N. Bull
- grid.8273.e0000 0001 1092 7967School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Henrik Cederquist
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
| | - Suvasthika Indrajith
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
| | - MingChao Ji
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
| | | | - Henning T. Schmidt
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
| | - Henning Zettergren
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
| | - Boxing Zhu
- grid.10548.380000 0004 1936 9377Department of Physics, Stockholm University, Stockholm, Sweden
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10
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Ashworth EK, Langeland J, Stockett MH, Lindkvist TT, Kjær C, Bull JN, Nielsen SB. Cryogenic Fluorescence Spectroscopy of Ionic Fluorones in Gaseous and Condensed Phases: New Light on Their Intrinsic Photophysics. J Phys Chem A 2022; 126:9553-9563. [PMID: 36529970 DOI: 10.1021/acs.jpca.2c07231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Fluorescence spectroscopy of gas-phase ions generated through electrospray ionization is an emerging technique able to probe intrinsic molecular photophysics directly without perturbations from solvent interactions. While there is ample scope for the ongoing development of gas-phase fluorescence techniques, the recent expansion into low-temperature operating conditions accesses a wealth of data on intrinsic fluorophore photophysics, offering enhanced spectral resolution compared with room-temperature measurements, without matrix effects hindering the excited-state dynamics. This perspective reviews current progress on understanding the photophysics of anionic fluorone dyes, which exhibit an unusually large Stokes shift in the gas phase, and discusses how comparison of gas- and condensed-phase fluorescence spectra can fingerprint structural dynamics. The capacity for temperature-dependent measurements of both fluorescence emission and excitation spectra helps establish the foundation for the use of fluorone dyes as fluorescent tags in macromolecular structure determination. We suggest ideas for technique development.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, University of East Anglia, NorwichNR4 7TJ, United Kingdom
| | - Jeppe Langeland
- Department of Physics and Astronomy, Aarhus University, Aarhus8000, Denmark
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691Stockholm, Sweden
| | | | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus8000, Denmark
| | - James N Bull
- School of Chemistry, University of East Anglia, NorwichNR4 7TJ, United Kingdom
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11
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Zhu B, Bull JN, Navarro Navarrete JE, Schmidt-May AF, Cederquist H, Schmidt HT, Zettergren H, Stockett MH. Radiative cooling of polyyne anions: C 4H - and C 6H -. J Chem Phys 2022; 157:174308. [DOI: 10.1063/5.0111144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The time-dependent photodetachment action spectra of the linear hydrocarbon anions C4H- and C6H- are investigated using the cryogenic electrostatic ion storage ring DESIREE. Radiative cooling characteristics of the ions on the millisecond to second timescale are probed by monitoring changes in the spectra as the ions cool by spontaneous infrared (IR) emission. A simple harmonic cascade (SHC) model is used to model the cooling processes. The cooling rates, extracted using Non-negative Matrix Factorization (NMF), are fit with 1/e lifetimes of 19 {plus minus} 2 s and 3.0 {plus minus} 0.2 s for C4H- and C6H-, respectively. For C4H-, the adiabatic detachment energy is determined from the cold ions' photodetachment spectra to be 3.45 {plus minus} 0.02 eV. The photodetachment spectrum and the ultraslow radiative cooling dynamics interpreted in the present work provide important data for understanding the thermal cooling properties of linear hydrocarbon anions and for refining the formation and destruction processes of these anions in astrochemical models.
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Affiliation(s)
- Boxing Zhu
- Department of Physics, Stockholm University Department of Physics, Sweden
| | - James N Bull
- School of Chemistry, University of East Anglia, United Kingdom
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12
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Zhu B, Bull JN, Ji M, Zettergren H, Stockett MH. Radiative cooling rates of substituted PAH ions. J Chem Phys 2022; 157:044303. [DOI: 10.1063/5.0089687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The unimolecular dissociation and infrared radiative cooling rates of cationic 1-hydroxypyrene (OHPyr$^+$, \ce{C16H10O+}) and 1-bromopyrene (BrPyr$^+$, \ce{C16H9Br+}) are measured using a cryogenic electrostatic \rev{ion beam} storage ring. A novel numerical approach is developed to analyze the time dependence of the dissociation rate and to determine the absolute scaling of the radiative cooling rate coefficient. The model results show that radiative cooling competes with dissociation below the critical total vibrational energies \revv{$E_c=5.39(1)$}~eV for OHPyr$^+$ and \revv{5.90(1)}~eV for BrPyr$^+$. These critical energies and implications for radiative cooling dynamics are important for astrochemical models concerned with energy dissipation and molecular lifecycles. The methods presented extend the utility of storage ring experiments on astrophysically relevant ions.
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Affiliation(s)
| | - James N Bull
- School of Chemistry, University of East Anglia, United Kingdom
| | - MingChao Ji
- Stockholm University Department of Physics, Sweden
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13
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Stockett MH, Bull JN, Schmidt HT, Zettergren H. Statistical vibrational autodetachment and radiative cooling rates of para-benzoquinone. Phys Chem Chem Phys 2022; 24:12002-12010. [PMID: 35535575 DOI: 10.1039/d2cp00490a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We report measurements of the statistical vibrational autodetachment (VAD, also called thermionic emission) and radiative cooling rates of isolated para-benzoquinone (pBQ, C6H4O2) radical anions using the cryogenic electrostatic ion storage ring facility DESIREE. The results are interpreted using master equation simulations with rate coefficients calculated using statistical detailed balance theory. The VAD rate is determined by measuring the time-dependent yield of neutral pBQ due to spontaneous electron emission from a highly-excited ensemble of anions formed in an electron-attachment ion source. Competition with radiative cooling quenches the VAD rate after a critical time of τc = 11.00(5) ms. Master equation simulations which reproduce the VAD yield provide an estimate of the initial effective vibrational temperature of the ions of 1100(20) K, and provide insight into the anion formation scenario. A second measurement of the radiative cooling rate of pBQ- stored for up to 0.5 s was achieved using time-dependent photodetachment action spectroscopy across the 2Au ← 2B2g and 2B2u ← 2B2g transitions. The rate at which hot-band contributions fade from the action spectrum is quantified by non-negative matrix factorisation. This is found to be commensurate with the average vibrational energy extracted from the simulations, with 1/e lifetimes of 0.16(3) s and 0.1602(7) s, respectively. Implications for astrochemistry are discussed.
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Affiliation(s)
- Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich, UK
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14
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Ashworth EK, Stockett MH, Kjær C, Bulman Page PC, Meech SR, Nielsen SB, Bull JN. Complexation of Green and Red Kaede Fluorescent Protein Chromophores by a Zwitterion to Probe Electrostatic and Induction Field Effects. J Phys Chem A 2022; 126:1158-1167. [PMID: 35138862 DOI: 10.1021/acs.jpca.1c10628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photophysics of green fluorescent protein (GFP) and red Kaede fluorescent protein (rKFP) are defined by the intrinsic properties of the light-absorbing chromophore and its interaction with the protein binding pocket. This work deploys photodissociation action spectroscopy to probe the absorption profiles for a series of synthetic GFP and rKFP chromophores as the bare anions and as complexes with the betaine zwitterion, which is assumed as a model for dipole microsolvation. Electronic structure calculations and energy decomposition analysis using Symmetry-Adapted Perturbation Theory are used to characterize gas-phase structures and complex cohesion forces. The calculations reveal a preponderance for coordination of betaine to the phenoxide deprotonation site predominantly through electrostatic forces. Calculations using the STEOM-DLPNO-CCSD method are able to reproduce absolute and relative vertical excitation energies for the bare anions and anion-betaine complexes. On the other hand, treatment of the betaine molecule with a point-charge model, in which the charges are computed from some common electron density population analysis schemes, show that just electrostatic and point-charge induction interactions are unable to account for the betaine-induced spectral shift. The present methodology could be applied to investigate cluster forces and optical properties in other gas-phase ion-zwitterion complexes.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000, Denmark
| | - Philip C Bulman Page
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | | | - James N Bull
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
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15
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Chiarinelli J, Barreiro-Lage D, Bolognesi P, RICHTER R, Zettergren H, Stockett MH, Díaz-Tendero S, Avaldi L. Electron and ion spectroscopy of the cyclo-alanine-alanine dipeptide. Phys Chem Chem Phys 2022; 24:5855-5867. [DOI: 10.1039/d1cp05811h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The VUV photoionisation and photofragmentation of cyclo-alanine-alanine (cAA) has been studiedin a joint experimental and theoretical work. The photoelectron spectrum and the photoelectron-photoion coincidence (PEPICO) measurements, which enable a control...
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16
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Bull JN, Anstöter CS, Stockett MH, Clarke CJ, Gibbard JA, Bieske EJ, Verlet JRR. Nonadiabatic Dynamics between Valence, Nonvalence, and Continuum Electronic States in a Heteropolycyclic Aromatic Hydrocarbon. J Phys Chem Lett 2021; 12:11811-11816. [PMID: 34870432 DOI: 10.1021/acs.jpclett.1c03532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Internal conversion between valence-localized and dipole-bound states is thought to be a ubiquitous process in polar molecular anions, yet there is limited direct evidence. Here, photodetachment action spectroscopy and time-resolved photoelectron imaging with a heteropolycyclic aromatic hydrocarbon (hetero-PAH) anion, deprotonated 1-pyrenol, is used to demonstrate a subpicosecond (τ1 = 160 ± 20 fs) valence to dipole-bound state internal conversion following excitation of the origin transition of the first valence-localized excited state. The internal conversion dynamics are evident in the photoelectron spectra and in the photoelectron angular distributions (β2 values) as the electronic character of the excited state population changes from valence to nonvalence. The dipole-bound state subsequently decays through mode-specific vibrational autodetachment with a lifetime τ2 = 11 ± 2 ps. These internal conversion and autodetachment dynamics are likely common in molecular anions but difficult to fingerprint due to the transient existence of the dipole-bound state. Potential implications of the present excited state dynamics for interstellar hetero-PAH anion formation are discussed.
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Affiliation(s)
- James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Cate S Anstöter
- Department of Chemistry, Temple University, 1901 N 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Mark H Stockett
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - Connor J Clarke
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jemma A Gibbard
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Evan J Bieske
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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17
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Gatchell M, Ameixa J, Ji M, Stockett MH, Simonsson A, Denifl S, Cederquist H, Schmidt HT, Zettergren H. Survival of polycyclic aromatic hydrocarbon knockout fragments in the interstellar medium. Nat Commun 2021; 12:6646. [PMID: 34789760 PMCID: PMC8599666 DOI: 10.1038/s41467-021-26899-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/28/2021] [Indexed: 11/26/2022] Open
Abstract
Laboratory studies play a crucial role in understanding the chemical nature of the interstellar medium (ISM), but the disconnect between experimental timescales and the timescales of reactions in space can make a direct comparison between observations, laboratory, and model results difficult. Here we study the survival of reactive fragments of the polycyclic aromatic hydrocarbon (PAH) coronene, where individual C atoms have been knocked out of the molecules in hard collisions with He atoms at stellar wind and supernova shockwave velocities. Ionic fragments are stored in the DESIREE cryogenic ion-beam storage ring where we investigate their decay for up to one second. After 10 ms the initially hot stored ions have cooled enough so that spontaneous dissociation no longer takes place at a measurable rate; a majority of the fragments remain intact and will continue to do so indefinitely in isolation. Our findings show that defective PAHs formed in energetic collisions with heavy particles may survive at thermal equilibrium in the interstellar medium indefinitely, and could play an important role in the chemistry in there, due to their increased reactivity compared to intact or photo-fragmented PAHs.
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Affiliation(s)
- Michael Gatchell
- Department of Physics, Stockholm University, 106 91, Stockholm, Sweden.
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria.
| | - João Ameixa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
| | - MingChao Ji
- Department of Physics, Stockholm University, 106 91, Stockholm, Sweden
| | - Mark H Stockett
- Department of Physics, Stockholm University, 106 91, Stockholm, Sweden
| | - Ansgar Simonsson
- Department of Physics, Stockholm University, 106 91, Stockholm, Sweden
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria
| | - Henrik Cederquist
- Department of Physics, Stockholm University, 106 91, Stockholm, Sweden
| | - Henning T Schmidt
- Department of Physics, Stockholm University, 106 91, Stockholm, Sweden
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18
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Coughlan NJA, Stockett MH, Kjær C, Ashworth EK, Bulman Page PC, Meech SR, Brøndsted Nielsen S, Blancafort L, Hopkins WS, Bull JN. Action spectroscopy of the isolated red Kaede fluorescent protein chromophore. J Chem Phys 2021; 155:124304. [PMID: 34598549 DOI: 10.1063/5.0063258] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Incorporation of fluorescent proteins into biochemical systems has revolutionized the field of bioimaging. In a bottom-up approach, understanding the photophysics of fluorescent proteins requires detailed investigations of the light-absorbing chromophore, which can be achieved by studying the chromophore in isolation. This paper reports a photodissociation action spectroscopy study on the deprotonated anion of the red Kaede fluorescent protein chromophore, demonstrating that at least three isomers-assigned to deprotomers-are generated in the gas phase. Deprotomer-selected action spectra are recorded over the S1 ← S0 band using an instrument with differential mobility spectrometry coupled with photodissociation spectroscopy. The spectrum for the principal phenoxide deprotomer spans the 480-660 nm range with a maximum response at ≈610 nm. The imidazolate deprotomer has a blue-shifted action spectrum with a maximum response at ≈545 nm. The action spectra are consistent with excited state coupled-cluster calculations of excitation wavelengths for the deprotomers. A third gas-phase species with a distinct action spectrum is tentatively assigned to an imidazole tautomer of the principal phenoxide deprotomer. This study highlights the need for isomer-selective methods when studying the photophysics of biochromophores possessing several deprotonation sites.
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Affiliation(s)
- Neville J A Coughlan
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000, Denmark
| | - Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Philip C Bulman Page
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Stephen R Meech
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | | | - Lluís Blancafort
- Institut de Química Computacional i Catálisi and Departament de Química, Universitat de Girona, C/M.A. Capmany 69, 17003 Girona, Spain
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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19
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Barreiro-Lage D, Bolognesi P, Chiarinelli J, Richter R, Zettergren H, Stockett MH, Carlini L, Diaz-Tendero S, Avaldi L. "Smart Decomposition" of Cyclic Alanine-Alanine Dipeptide by VUV Radiation: A Seed for the Synthesis of Biologically Relevant Species. J Phys Chem Lett 2021; 12:7379-7386. [PMID: 34324354 DOI: 10.1021/acs.jpclett.1c01788] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A combined experimental and theoretical study shows how the interaction of VUV radiation with cyclo-(alanine-alanine), one of the 2,5-diketopiperazines (DKPs), produces reactive oxazolidinone intermediates. The theoretical simulations reveal that the interaction of these intermediates with other neutral and charged fragments, released in the molecular decomposition, leads either to the reconstruction of the cyclic dipeptide or to the formation of longer linear peptide chains. These results may explain how DKPs could have, on one hand, survived hostile chemical environments and, on the other, provided the seed for amino acid polymerization. Shedding light on the mechanisms of production of such prebiotic building blocks is of paramount importance to understanding the abiotic synthesis of relevant biologically active compounds.
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Affiliation(s)
- Darío Barreiro-Lage
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Paola Bolognesi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Jacopo Chiarinelli
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Robert Richter
- Elettra Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | | | - Mark H Stockett
- Department of Physics, Stockholm University, Se-10691 Stockholm, Sweden
| | - Laura Carlini
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Sergio Diaz-Tendero
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Institute for Advanced Research in Chemical Science (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Lorenzo Avaldi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
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20
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Giacomozzi L, Kjær C, Brøndsted Nielsen S, Ashworth EK, Bull JN, Stockett MH. Non-statistical fragmentation in photo-activated flavin mononucleotide anions. J Chem Phys 2021; 155:044305. [PMID: 34340366 DOI: 10.1063/5.0056415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The spectroscopy and photo-induced dissociation of flavin mononucleotide anions in vacuo are investigated over the 300-500 nm wavelength range. Comparison of the dependence of fragment ion yields as a function of deposited photon energy with calculated dissociation energies and collision-induced dissociation measurements performed under single-collision conditions suggests that a substantial fraction of photo-activated ions decompose through non-statistical fragmentation pathways. Among these pathways is the dominant photo-induced fragmentation channel, the loss of a fragment identified as formylmethylflavin. The fragment ion specific action spectra reveal electronic transition energies close to those for flavins in solution and previously published gas-phase measurements, although the photo-fragment yield upon excitation of the S2 ← S0 transition appears to be suppressed.
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Affiliation(s)
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | | | - Eleanor K Ashworth
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden
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21
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Kjær C, Langeland J, Lindkvist TT, Sørensen ER, Stockett MH, Kjaergaard HG, Nielsen SB. A new setup for low-temperature gas-phase ion fluorescence spectroscopy. Rev Sci Instrum 2021; 92:033105. [PMID: 33820085 DOI: 10.1063/5.0038880] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Here, we present a new instrument named LUNA2 (LUminescence iNstrument in Aarhus 2), which is purpose-built to measure dispersed fluorescence spectra of gaseous ions produced by electrospray ionization and cooled to low temperatures (<100 K). LUNA2 is, as an earlier room-temperature setup (LUNA), optimized for a high collection efficiency of photons and includes improvements based on our operational experience with LUNA. The fluorescence cell is a cylindrical Paul trap made of copper with a hole in the ring electrode to permit laser light to interact with the trapped ions, and one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The entrance and exit electrodes are both in physical contact with the liquid-nitrogen cooling unit to reduce cooling times. Mass selection is done in a two-step scheme where, first, high-mass ions are ejected followed by low-mass ions according to the Mathieu stability region. This scheme may provide a higher mass resolution than when only one DC voltage is used. Ions are irradiated by visible light delivered from a nanosecond 20-Hz pulsed laser, and dispersed fluorescence is measured with a spectrometer combined with an iCCD camera that allows intensification of the signal for a short time interval. LUNA2 contains an additional Paul trap that can be used for mass selection before ions enter the fluorescence cell, which potentially is relevant to diminishing RF heating in the cold trap. Successful operation of the setup is demonstrated from experiments with rhodamine dyes and oxazine-4, and spectral changes with temperature are identified.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Jeppe Langeland
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | | | - Emma Rostal Sørensen
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Henrik G Kjaergaard
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
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22
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Kjær C, Jones NC, Stockett MH, Hoffmann SV, Nielsen SB. Circular dichroism, anisotropy and absorption spectroscopy of chlorophyll b in methanol and mixed methanol-water solutions. Phys Chem Chem Phys 2020; 22:26961-26966. [PMID: 33206737 DOI: 10.1039/d0cp03284k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The spectroscopic properties of chlorophyll (Chl) strongly depend on interactions with other Chl molecules, a fact that nature exploits in light harvesting by photosynthetic proteins. In solution, complex Chl aggregates are formed that depend not only on the solvent, but also on the detailed preparation procedure. Here we report synchrotron radiation circular dichroism (SRCD) spectra of Chlb in methanol (MeOH) and MeOH/H2O mixtures; in the latter, water molecules assist in the formation of Chl aggregates as Chlb is too hydrophobic to dissolve in water. The magnitude of the most prominent CD signal increases up to 100-fold over time (2-15 hours) when the water content is increased from 0 to 50% in volume, the signal is non-conservative (almost exclusively negative), and sensitive to sample preparation. Three different types of signature CD spectra (Types A to C) are identified depending on preparation, and the change in CD signal over time and with temperature is further analyzed with anisotropy spectroscopy (ratio of simultaneously recorded CD to absorption) and principal component analysis (PCA). We show that CD is clearly superior to pure absorption spectroscopy in identifying structural changes, and anisotropy spectroscopy further increases the sensitivity towards smaller structural changes. PCA on temperature dependent CD data show that depending on preparation, and thus the type of aggregate as revealed by the CD signature, either one (Type A) or two chiral species (Type B) are identified in the spectra, further evidencing the complex nature of Chlb aggregates. Furthermore, the CD signal decreases linearly with volume when a sample of Chlb in MeOH/H2O (i.e., a sample of Chlb aggregates) is diluted, which implies that the aggregation process is irreversible: once aggregates are formed, they largely do not revert back to monomers. However, anisotropy spectroscopy reveals that there are small changes in the aggregates, not directly noticeable in CD and absorption. The work presented here demonstrates, compared to absorption spectroscopy, a clear advantage of CD and anisotropy spectroscopy in studying the complex evolution of Chl samples with time and temperature.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Denmark.
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23
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Stockett MH, Bull JN, Buntine JT, Carrascosa E, Ji M, Kono N, Schmidt HT, Zettergren H. Unimolecular fragmentation and radiative cooling of isolated PAH ions: A quantitative study. J Chem Phys 2020; 153:154303. [PMID: 33092387 DOI: 10.1063/5.0027773] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Time-resolved spontaneous and laser-induced unimolecular fragmentation of perylene cations (C20H12 +) has been measured on timescales up to 2 s in a cryogenic electrostatic ion beam storage ring. We elaborate a quantitative model, which includes fragmentation in competition with radiative cooling via both vibrational and electronic (recurrent fluorescence) de-excitation. Excellent agreement with experimental results is found when sequential fragmentation of daughter ions co-stored with the parent perylene ions is included in the model. Based on the comparison of the model to experiment, we constrain the oscillator strength of the D1 → D0 emissive electronic transition in perylene (fRF = 0.055 ± 0.011), as well as the absolute absorption cross section of the D5 ← D0 excitation transition (σabs > 670 Mb). The former transition is responsible for the laser-induced and recurrent fluorescence of perylene, and the latter is the most prominent in the absorption spectrum. The vibrational cooling rate is found to be consistent with the simple harmonic cascade approximation. Quantitative experimental benchmarks of unimolecular processes in polycyclic aromatic hydrocarbon ions like perylene are important for refining astrochemical models.
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Affiliation(s)
- Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Jack T Buntine
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Eduardo Carrascosa
- Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland
| | - MingChao Ji
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Naoko Kono
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Henning T Schmidt
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
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24
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Abstract
Dye molecules based on the xanthene moiety are widely used as fluorescent probes in bioimaging and technological applications due to their large absorption cross-section for visible light and high fluorescence quantum yield. These applications require a clear understanding of the dye's inherent photophysics and the effect of a condensed-phase environment. Here, the gas-phase photophysics of the rose bengal doubly deprotonated dianion [RB - 2H]2-, deprotonated monoanion [RB - H]-, and doubly deprotonated radical anion [RB - 2H]•- is investigated using photodetachment, photoelectron, and dispersed fluorescence action spectroscopies, and tandem ion mobility spectrometry (IMS) coupled with laser excitation. For [RB - 2H]2-, photodetachment action spectroscopy reveals a clear band in the visible (450-580 nm) with vibronic structure. Electron affinity and repulsive Coulomb barrier (RCB) properties of the dianion are characterized using frequency-resolved photoelectron spectroscopy, revealing a decreased RCB compared with that of fluorescein dianions due to electron delocalization over halogen atoms. Monoanions [RB - H]- and [RB - 2H]•- differ in nominal mass by 1 Da but are difficult to study individually using action spectroscopies that isolate target ions using low-resolution mass spectrometry. This work shows that the two monoanions are readily distinguished and probed using the IMS-photo-IMS and photo-IMS-photo-IMS strategies, providing distinct but overlapping photodissociation action spectra in the visible spectral range. Gas-phase fluorescence was not detected from photoexcited [RB - 2H]2- due to rapid electron ejection. However, both [RB - H]- and [RB - 2H]•- show a weak fluorescence signal. The [RB - H]- action spectra show a large Stokes shift of ∼1700 cm-1, while the [RB - 2H]•- action spectra show no appreciable Stokes shift. This difference is explained by considering geometries of the ground and fluorescing states.
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Affiliation(s)
- Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000, Denmark
| | - Steven Daly
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumiére Matiére UMR 5306, F-69100 Villeurbanne, France
| | - Evan J Bieske
- School of Chemistry, University of Melbourne, Parkville VIC 3010, Australia
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | | | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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25
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Kjær C, Zhao Y, Stockett MH, Chen L, Hansen K, Nielsen SB. Gas-phase Förster resonance energy transfer in mass-selected ions with methylene or peptide linkers between two dyes: a concerted dance of charges. Phys Chem Chem Phys 2020; 22:11095-11100. [DOI: 10.1039/d0cp01287d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Emission from gaseous rhodamine 640 is redshifted when the dye is tethered to rhodamine 575 due to internal Coulomb interaction.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy
- Aarhus University
- Denmark
| | - Ying Zhao
- State Key Laboratory and Institute of Elemento-Organic Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
- P. R. China
| | | | - Li Chen
- State Key Laboratory and Institute of Elemento-Organic Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
- P. R. China
| | - Klavs Hansen
- Center for Joint Quantum Studies and Department of Physics
- Tianjin University
- 92 Weijin Road
- China
- Department of Physics
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26
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Bull JN, Scholz MS, Carrascosa E, Kristiansson MK, Eklund G, Punnakayathil N, de Ruette N, Zettergren H, Schmidt HT, Cederquist H, Stockett MH. Ultraslow radiative cooling of Cn− (n = 3–5). J Chem Phys 2019; 151:114304. [DOI: 10.1063/1.5114678] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- James N. Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Michael S. Scholz
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Eduardo Carrascosa
- Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland
| | | | - Gustav Eklund
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | | | | | | | - Henrik Cederquist
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Mark H. Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
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Kjaer C, Lissau H, Gravesen Salinas NK, Østergaard Madsen A, Stockett MH, Storm FE, Holm Hansen T, Andersen JU, Laursen BW, Mikkelsen KV, Brøndsted Nielsen M, Brøndsted Nielsen S. Luminescence Spectroscopy of Rhodamine Homodimer Dications in Vacuo
Reveals Strong Dye-Dye Interactions. Chemphyschem 2019; 20:533-537. [DOI: 10.1002/cphc.201800933] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/04/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Christina Kjaer
- Department of Physics and Astronomy; Aarhus University; Denmark
| | | | | | | | | | - Freja E. Storm
- Department of Chemistry; University of Copenhagen; Denmark
| | | | | | - Bo W. Laursen
- Department of Chemistry; University of Copenhagen; Denmark
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28
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Stockett MH, Björkhage M, Cederquist H, Schmidt HT, Zettergren H. Storage time dependent photodissociation action spectroscopy of polycyclic aromatic hydrocarbon cations in the cryogenic electrostatic storage ring DESIREE. Faraday Discuss 2019; 217:126-137. [DOI: 10.1039/c8fd00161h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The intrinsic absorption profile and radiative cooling rate of coronene cations are reported.
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Bull JN, Buntine JT, Scholz MS, Carrascosa E, Giacomozzi L, Stockett MH, Bieske EJ. Photodetachment and photoreactions of substituted naphthalene anions in a tandem ion mobility spectrometer. Faraday Discuss 2019; 217:34-46. [DOI: 10.1039/c8fd00217g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Tandem IMS-laser-IMS is used to probe the intrinsic electronic absorptions of deprotonated substituted naphthalene anions.
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de Ruette N, Dochain A, Launoy T, Nascimento RF, Kaminska M, Stockett MH, Vaeck N, Schmidt HT, Cederquist H, Urbain X. Mutual Neutralization of O^{-} with O^{+} and N^{+} at Subthermal Collision Energies. Phys Rev Lett 2018; 121:083401. [PMID: 30192576 DOI: 10.1103/physrevlett.121.083401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Indexed: 06/08/2023]
Abstract
We have measured total absolute cross sections for the mutual neutralization (MN) of O^{-} with O^{+} and N^{+}. A fine resolution (of about 50 meV) in the kinetic energy spectra of the product neutral atoms allows unique identification of the atomic states participating in the mutual neutralization process. Cross sections and branching ratios have also been calculated down to 1 meV center-of-mass collision energy for these two systems, with a multichannel Landau-Zener model and an asymptotic method for the ionic-covalent coupling matrix elements. The importance of two-electron processes in one-electron transfer is demonstrated by the dominant contribution of a core-excited configuration of the nitrogen atom in N^{+}+O^{-} collisions. This effect is partially accounted for by introducing configuration mixing in the evaluation of coupling matrix elements.
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Affiliation(s)
- N de Ruette
- Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden
| | - A Dochain
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - T Launoy
- Laboratoire de Chimie Quantique et Photophysique, Université Libre de Bruxelles, B-1050 Brussels, Belgium
| | - R F Nascimento
- Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden
- Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Petrópolis, 25620-003 RJ, Brazil
| | - M Kaminska
- Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden
- Institute of Physics, Jan Kochanowski University, 25-369 Kielce, Poland
| | - M H Stockett
- Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden
| | - N Vaeck
- Laboratoire de Chimie Quantique et Photophysique, Université Libre de Bruxelles, B-1050 Brussels, Belgium
| | - H T Schmidt
- Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden
| | - X Urbain
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
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31
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Bull JN, Carrascosa E, Giacomozzi L, Bieske EJ, Stockett MH. Ion mobility action spectroscopy of flavin dianions reveals deprotomer-dependent photochemistry. Phys Chem Chem Phys 2018; 20:19672-19681. [PMID: 30014081 PMCID: PMC6063075 DOI: 10.1039/c8cp03244k] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Photo-induced proton transfer, deprotomer-dependent photochemistry, and intramolecular charge transfer in flavin anions are investigated using action spectroscopy.
The intrinsic optical properties and photochemistry of flavin adenine dinucleotide (FAD) dianions are investigated using a combination of tandem ion mobility spectrometry and action spectroscopy. Two principal isomers are observed, the more stable form being deprotonated on the isoalloxazine group and a phosphate (N-3,PO4 deprotomer), and the other on the two phosphates (PO4,PO4 deprotomer). Ion mobility data and electronic action spectra suggest that photo-induced proton transfer occurs from the isoalloxazine group to a phosphate group, converting the PO4,PO4 deprotomer to the N-3,PO4 deprotomer. Comparisons of the isomer selective action spectra of FAD dianions and flavin monoanions with solution spectra and gas-phase photodissociation action spectra suggests that solvation shifts the electronic absorption of the deprotonated isoalloxazine group to higher energy. This is interpreted as evidence for significant charge transfer in the lowest optical transition of deprotonated isoalloxazine. Overall, this work demonstrates that the site of deprotonation of flavin anions strongly affects their electronic absorptions and photochemistry.
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Affiliation(s)
- James N Bull
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Eduardo Carrascosa
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | | | - Evan J Bieske
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mark H Stockett
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia and Department of Physics, Stockholm University, Stockholm, Sweden.
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32
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Giacomozzi L, Kjær C, Langeland Knudsen J, Andersen LH, Brøndsted Nielsen S, Stockett MH. Absorption and luminescence spectroscopy of mass-selected flavin adenine dinucleotide mono-anions. J Chem Phys 2018; 148:214309. [PMID: 29884035 DOI: 10.1063/1.5024028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We report the absorption profile of isolated Flavin Adenine Dinucleotide (FAD) mono-anions recorded using photo-induced dissociation action spectroscopy. In this charge state, one of the phosphoric acid groups is deprotonated and the chromophore itself is in its neutral oxidized state. These measurements cover the first four optical transitions of FAD with excitation energies from 2.3 to 6.0 eV (210-550 nm). The S0 → S2 transition is strongly blue shifted relative to aqueous solution, supporting the view that this transition has a significant charge-transfer character. The remaining bands are close to their solution-phase positions. This confirms that the large discrepancy between quantum chemical calculations of vertical transition energies and solution-phase band maxima cannot be explained by solvent effects. We also report the luminescence spectrum of FAD mono-anions in vacuo. The gas-phase Stokes shift for S1 is 3000 cm-1, which is considerably larger than any previously reported for other molecular ions and consistent with a significant displacement of the ground and excited state potential energy surfaces. Consideration of the vibronic structure is thus essential for simulating the absorption and luminescence spectra of flavins.
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Affiliation(s)
- L Giacomozzi
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - C Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | | | - L H Andersen
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | | | - M H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden
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de Ruette N, Wolf M, Giacomozzi L, Alexander JD, Gatchell M, Stockett MH, Haag N, Zettergren H, Schmidt HT, Cederquist H. DESIREE electrospray ion source test bench and setup for collision induced dissociation experiments. Rev Sci Instrum 2018; 89:075102. [PMID: 30068131 DOI: 10.1063/1.5030528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this paper, we give a detailed description of an electrospray ion source test bench and a single-pass setup for ion fragmentation studies at the Double ElectroStatic Ion Ring ExpEriment infrastructure at Stockholm University. This arrangement allows for collision-induced dissociation experiments at the center-of-mass energies between 10 eV and 1 keV. Charged fragments are analyzed with respect to their kinetic energies (masses) by means of an electrostatic energy analyzer with a wide angular acceptance and adjustable energy resolution.
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Affiliation(s)
- N de Ruette
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - M Wolf
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - L Giacomozzi
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - J D Alexander
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - M Gatchell
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - N Haag
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - H T Schmidt
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
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Chartkunchand KC, Stockett MH, Anderson EK, Eklund G, Kristiansson MK, Kamińska M, de Ruette N, Blom M, Björkhage M, Källberg A, Löfgren P, Reinhed P, Rosén S, Simonsson A, Zettergren H, Schmidt HT, Cederquist H. Dianion diagnostics in DESIREE: High-sensitivity detection of C n2- from a sputter ion source. Rev Sci Instrum 2018; 89:033112. [PMID: 29604753 DOI: 10.1063/1.5010077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A sputter ion source with a solid graphite target has been used to produce dianions with a focus on carbon cluster dianions, Cn2-, with n = 7-24. Singly and doubly charged anions from the source were accelerated together to kinetic energies of 10 keV per atomic unit of charge and injected into one of the cryogenic (13 K) ion-beam storage rings of the Double ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous decay of internally hot Cn2- dianions injected into the ring yielded Cn- anions with kinetic energies of 20 keV, which were counted with a microchannel plate detector. Mass spectra produced by scanning the magnetic field of a 90° analyzing magnet on the ion injection line reflect the production of internally hot C72- - C242- dianions with lifetimes in the range of tens of microseconds to milliseconds. In spite of the high sensitivity of this method, no conclusive evidence of C62- was found while there was a clear C72- signal with the expected isotopic distribution. This is consistent with earlier experimental studies and with theoretical predictions. An upper limit is deduced for a C62- signal that is two orders-of-magnitude smaller than that for C72-. In addition, CnO2- and CnCu2- dianions were detected.
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Affiliation(s)
- K C Chartkunchand
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - E K Anderson
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - G Eklund
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M K Kristiansson
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M Kamińska
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - N de Ruette
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M Blom
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M Björkhage
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - A Källberg
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - P Löfgren
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - P Reinhed
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - S Rosén
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - A Simonsson
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - H T Schmidt
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
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35
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Stockett MH. Photo-induced proton-coupled electron transfer and dissociation of isolated flavin adenine dinucleotide mono-anions. Phys Chem Chem Phys 2018; 19:25829-25833. [PMID: 28745349 DOI: 10.1039/c7cp04068g] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The intrinsic optical absorption spectrum and photo-dissociation pathways of flavin adenine dinucleotide (FAD) mono-anions isolated in vacuo are probed using photo-induced dissociation (PID) action spectroscopy. The main photo-products are lumichrome and formylmethylflavin. Evidence is presented that the dissociation pathway leading to these products is non-statistical i.e. occurs during the excited state lifetime. This suggests that the stacking of the adenine and alloxazine chromophores, which enables ultra-fast quenching of the flavin excited state by photo-induced electron transfer in aqueous solution, is inhibited in vacuo. These results provide firm experimental confirmation that lumichrome formation from flavins proceeds via photo-induced, intra-molecular proton-coupled electron transfer.
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Affiliation(s)
- Mark H Stockett
- Stockholm University Department of Physics, Stockholm, Sweden.
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36
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Stockett MH, Boesen M, Houmøller J, Brøndsted Nielsen S. Frontispiece: Accessing the Intrinsic Nature of Electronic Transitions from Gas‐Phase Spectroscopy of Molecular Ion/Zwitterion Complexes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/anie.201781361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | - Mikkel Boesen
- Department of Physics and Astronomy Aarhus University Denmark
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Stockett MH, Boesen M, Houmøller J, Brøndsted Nielsen S. Frontispiz: Accessing the Intrinsic Nature of Electronic Transitions from Gas‐Phase Spectroscopy of Molecular Ion/Zwitterion Complexes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201781361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
| | - Mikkel Boesen
- Department of Physics and Astronomy Aarhus University Denmark
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Stockett MH, Boesen M, Houmøller J, Brøndsted Nielsen S. Accessing the Intrinsic Nature of Electronic Transitions from Gas‐Phase Spectroscopy of Molecular Ion/Zwitterion Complexes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | - Mikkel Boesen
- Department of Physics and Astronomy Aarhus University Denmark
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39
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Stockett MH, Boesen M, Houmøller J, Brøndsted Nielsen S. Accessing the Intrinsic Nature of Electronic Transitions from Gas‐Phase Spectroscopy of Molecular Ion/Zwitterion Complexes. Angew Chem Int Ed Engl 2017; 56:3490-3495. [DOI: 10.1002/anie.201611320] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Indexed: 11/07/2022]
Affiliation(s)
| | - Mikkel Boesen
- Department of Physics and Astronomy Aarhus University Denmark
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40
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Stockett MH, Kjær C, Linder MK, Detty MR, Nielsen SB. Luminescence spectroscopy of chalcogen substituted rhodamine cations in vacuo. Photochem Photobiol Sci 2017; 16:779-784. [DOI: 10.1039/c7pp00049a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A library of fluorescent rhodamine cations has been characterized with view to their potential use in gas-phase structural biology experiments.
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Affiliation(s)
- Mark H. Stockett
- Aarhus University Department of Physics and Astronomy
- Aarhus
- Denmark
| | - Christina Kjær
- Aarhus University Department of Physics and Astronomy
- Aarhus
- Denmark
| | - Michelle K. Linder
- State University of New York University at Buffalo Department of Chemistry
- Buffalo
- USA
| | - Michael R. Detty
- State University of New York University at Buffalo Department of Chemistry
- Buffalo
- USA
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Kjær C, Brøndsted Nielsen S, Stockett MH. Sibling rivalry: intrinsic luminescence from two xanthene dye monoanions, resorufin and fluorescein, provides evidence for excited-state proton transfer in the latter. Phys Chem Chem Phys 2017; 19:24440-24444. [DOI: 10.1039/c7cp04689h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Excited-state proton transfer in gas-phase fluorescein monoanions results in a broad, featureless emission band and a large Stokes shift compared to resorufin, which shares the same xanthene core structure.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy
- Aarhus University
- Denmark
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42
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Kjær C, Stockett MH, Pedersen BM, Nielsen SB. Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments. J Phys Chem B 2016; 120:12105-12110. [PMID: 27933942 DOI: 10.1021/acs.jpcb.6b10547] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The microenvironments in photosynthetic proteins affect the absorption by chlorophyll (Chl) pigments. It is, however, a challenge to disentangle the impact on the transition energies of different perturbations, for example, the global electrostatics of the protein (nonbonded environmental effects), exciton coupling between Chl's, conformational variations, and binding of an axial ligand to the magnesium center. This is needed to distinguish between the two most commonly proposed mechanisms for energy transport in photosynthetic proteins, relying on either weakly or strongly coupled pigments. Here, on the basis of photodissociation action spectroscopy, we establish that the redshift of the Soret absorption band due to binding of a negatively charged carboxylate (as present in aspartic acid and glutamic acid residues) is 0.1-0.2 eV for Chl a and b. This effect is almost enough to reproduce the well-known green color of plants and can account for the strong spectral variation between Chl's. The experimental data serve to benchmark future high-level calculations of excited-state energies. Finally, we demonstrate that complexes between Chl a and histidine, tagged by a quaternary ammonium ion, can be made in the gas phase by electrospray ionization, but more work is needed to produce enough ions for gas-phase spectroscopy.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
| | - Mark H Stockett
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
| | - Bjarke M Pedersen
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
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Stockett MH, Houmøller J, Støchkel K, Svendsen A, Brøndsted Nielsen S. A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy. Rev Sci Instrum 2016; 87:053103. [PMID: 27250388 DOI: 10.1063/1.4948316] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.
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Affiliation(s)
- Mark H Stockett
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Jørgen Houmøller
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Kristian Støchkel
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Annette Svendsen
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
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Andersen LH, Bochenkova AV, Houmøller J, Kiefer HV, Lattouf E, Stockett MH. A PYP chromophore acts as a 'photoacid' in an isolated hydrogen bonded complex. Phys Chem Chem Phys 2016; 18:9909-13. [PMID: 27009407 DOI: 10.1039/c6cp00433d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The light-induced response of a neutral Photoactive Yellow Protein chromophore in a hydrogen-bonded complex with a proton acceptor has been studied by dual-detection action absorption spectroscopy and density functional theory. We show that the chromophore is a 'photoacid' and that ultrafast excited-state proton transfer might be operative in an isolated complex.
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Affiliation(s)
- Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark.
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45
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Milne BF, Kjaer C, Houmøller J, Stockett MH, Toker Y, Rubio A, Nielsen SB. On the Exciton Coupling between Two Chlorophyll Pigments in the Absence of a Protein Environment: Intrinsic Effects Revealed by Theory and Experiment. Angew Chem Int Ed Engl 2016; 55:6248-51. [DOI: 10.1002/anie.201601979] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Bruce F. Milne
- CFisUC, Department of Physics; University of Coimbra; Rua Larga 3004-516 Coimbra Portugal
| | - Christina Kjaer
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
| | - Jørgen Houmøller
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
| | - Mark H. Stockett
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
| | - Yoni Toker
- Institute of Nanotechnology and Advanced Materials; Bar-Ilan University; Ramat-Gan 5290002 Israel
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter; Luruper Chaussee 149 22761 Hamburg Germany
- Nano-Bio Spectroscopy Group and ETSF; Universidad del País Vasco, CFM CSIC-UPV/EHU-MPC & DIPC; 20018 San Sebastián Spain
| | - Steen Brøndsted Nielsen
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
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Milne BF, Kjaer C, Houmøller J, Stockett MH, Toker Y, Rubio A, Nielsen SB. On the Exciton Coupling between Two Chlorophyll Pigments in the Absence of a Protein Environment: Intrinsic Effects Revealed by Theory and Experiment. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601979] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Bruce F. Milne
- CFisUC, Department of Physics; University of Coimbra; Rua Larga 3004-516 Coimbra Portugal
| | - Christina Kjaer
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
| | - Jørgen Houmøller
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
| | - Mark H. Stockett
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
| | - Yoni Toker
- Institute of Nanotechnology and Advanced Materials; Bar-Ilan University; Ramat-Gan 5290002 Israel
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter; Luruper Chaussee 149 22761 Hamburg Germany
- Nano-Bio Spectroscopy Group and ETSF; Universidad del País Vasco, CFM CSIC-UPV/EHU-MPC & DIPC; 20018 San Sebastián Spain
| | - Steen Brøndsted Nielsen
- Department of Physics and Astronomy; Aarhus University; Ny Munkegade DK-8000 Aarhus C Denmark
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Stockett MH, Nielsen SB. Transition energies of benzoquinone anions are immune to symmetry breaking by a single water molecule. Phys Chem Chem Phys 2016; 18:6996-7000. [DOI: 10.1039/c5cp06095h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Breaking the symmetry of the p-benzoquinone anion by a single water molecule has almost no effect on its transition energies.
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Affiliation(s)
- Mark H. Stockett
- Department of Physics and Astronomy
- Aarhus University
- Aarhus
- Denmark
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Stockett MH, Gatchell M, Chen T, de Ruette N, Giacomozzi L, Wolf M, Schmidt HT, Zettergren H, Cederquist H. Threshold energies for single-carbon knockout from polycyclic aromatic hydrocarbons. J Phys Chem Lett 2015; 6:4504-4509. [PMID: 26523738 DOI: 10.1021/acs.jpclett.5b02080] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have measured absolute cross sections for ultrafast (femtosecond) single-carbon knockout from polycyclic aromatic hydrocarbon (PAH) cations as functions of He–PAH center-of-mass collision energy in the 10–200 eV range. Classical molecular dynamics (MD) simulations cover this range and extend up to 105 eV. The shapes of the knockout cross sections are well-described by a simple analytical expression yielding experimental and MD threshold energies of EthExp = 32.5 ± 0.4 eV and EthMD = 41.0 ± 0.3 eV, respectively. These are the first measurements of knockout threshold energies for molecules isolated in vacuo. We further deduce semiempirical (SE) and MD displacement energies, i.e., the energy transfers to the PAH molecules at the threshold energies for knockout, of TdispSE = 23.3 ± 0.3 eV and TdispMD = 27.0 ± 0.3 eV. The semiempirical results compare favorably with measured displacement energies for graphene (Tdisp = 23.6 eV).
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Affiliation(s)
- M H Stockett
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark
| | - M Gatchell
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - T Chen
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - N de Ruette
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - L Giacomozzi
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - M Wolf
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - H T Schmidt
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
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Chen T, Gatchell M, Stockett MH, Delaunay R, Domaracka A, Micelotta ER, Tielens AGGM, Rousseau P, Adoui L, Huber BA, Schmidt HT, Cederquist H, Zettergren H. Formation of H2 from internally heated polycyclic aromatic hydrocarbons: excitation energy dependence. J Chem Phys 2015; 142:144305. [PMID: 25877576 DOI: 10.1063/1.4917021] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have investigated the effectiveness of molecular hydrogen (H2) formation from Polycyclic Aromatic Hydrocarbons (PAHs) which are internally heated by collisions with keV ions. The present and earlier experimental results are analyzed in view of molecular structure calculations and a simple collision model. We estimate that H2 formation becomes important for internal PAH temperatures exceeding about 2200 K, regardless of the PAH size and the excitation agent. This suggests that keV ions may effectively induce such reactions, while they are unlikely due to, e.g., absorption of single photons with energies below the Lyman limit. The present analysis also suggests that H2 emission is correlated with multi-fragmentation processes, which means that the [PAH-2H](+) peak intensities in the mass spectra may not be used for estimating H2-formation rates.
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Affiliation(s)
- T Chen
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - M Gatchell
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - R Delaunay
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - A Domaracka
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - E R Micelotta
- Université Paris Sud, Institut d'Astrophysique Spatiale, UMR 8617, 91405 Orsay, France
| | - A G G M Tielens
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
| | - P Rousseau
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - L Adoui
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - B A Huber
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - H T Schmidt
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
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Stockett MH, Brøndsted Nielsen S. Communication: Does a single CH3CN molecule attached to Ru(bipy)3(2+) affect its absorption spectrum? J Chem Phys 2015; 142:171102. [PMID: 25956080 DOI: 10.1063/1.4919781] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Tris(bipyridine)ruthenium(II) (Ru(bipy)3 (2+)) is a prototypical transition metal coordination complex whose photophysical properties have attracted considerable attention. A much debated issue is whether the metal-to-ligand charge transfer (MLCT) transition that accounts for the complex's beautiful red color is fully delocalized across all three bipyridine ligands or located on just one ligand. Here, we show based on gas-phase action spectroscopy that attachment of a single acetonitrile molecule does not change the absorption spectrum from that of the bare ions, which is indicative of a delocalized state. However, the gas-phase spectra of the bare and one solvent molecule complexes are significantly blueshifted relative to that obtained in bulk acetonitrile, which suggests that in solution the polarizability of many solvent molecules working together can localize the MLCT state. Our data clearly show that more than one solvent molecule is needed to break the symmetry of the MLCT excited state and reproduce its solution-phase characteristics.
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Affiliation(s)
- M H Stockett
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
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