1
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Vandaele E, Mališ M, Luber S. The Role of Aqueous Solvation on the Intersystem Crossing of Nitrophenols. J Chem Theory Comput 2024; 20:3258-3272. [PMID: 38606908 PMCID: PMC11044273 DOI: 10.1021/acs.jctc.3c01400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/27/2024] [Accepted: 03/29/2024] [Indexed: 04/13/2024]
Abstract
The photochemistry of nitrophenols is a source of smog as nitrous acid is formed from their photolysis. Nevertheless, computational studies of the photochemistry of these widespread toxic molecules are scarce. In this work, the initial photodeactivation of ortho-nitrophenol and para-nitrophenol is modeled, both in gas phase and in aqueous solution to simulate atmospheric and aerosol environments. A large number of excited states, six for ortho-nitrophenol and 11 for para-nitrophenol, have been included and were all populated during the decay. Moreover, periodic time-dependent density functional theory (TDDFT) is used for both the explicitly included solvent and the solute. A comparison to periodic QM/MM (TDDFT/MM), with electrostatic embedding, is made, showing notable differences between the decays of solvated nitrophenols simulated with QM/MM and full (TD)DFT. A reduced intersystem crossing in aqueous solution could be observed thanks to the surface hopping approach using explicit, periodic TDDFT solvation including spin-orbit couplings.
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Affiliation(s)
- Eva Vandaele
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Momir Mališ
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Sandra Luber
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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2
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Crane S, Garrow M, Lane PD, Robertson K, Waugh A, Woolley JM, Stavros VG, Paterson MJ, Greaves SJ, Townsend D. The Value of Different Experimental Observables: A Transient Absorption Study of the Ultraviolet Excitation Dynamics Operating in Nitrobenzene. J Phys Chem A 2023; 127:6425-6436. [PMID: 37494478 PMCID: PMC10424241 DOI: 10.1021/acs.jpca.3c02654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/16/2023] [Indexed: 07/28/2023]
Abstract
Excess energy redistribution dynamics operating in nitrobenzene under hexane and isopropanol solvation were investigated using ultrafast transient absorption spectroscopy (TAS) with a 267 nm pump and a 340-750 nm white light continuum probe. The use of a nonpolar hexane solvent provides a proxy to the gas-phase environment, and the findings are directly compared with a recent time-resolved photoelectron imaging (TRPEI) study on nitrobenzene using the same excitation wavelength [L. Saalbach et al., J. Phys. Chem. A 2021, 125, 7174-7184]. Of note is the observation of a 1/e lifetime of 3.5-6.7 ps in the TAS data that was absent in the TRPEI measurements. This is interpreted as a dynamical signature of the T2 state in nitrobenzene─analogous to observations in the related nitronaphthalene system, and additionally supported by previous quantum chemistry calculations. The discrepancy between the TAS and TRPEI measurements is discussed, with the overall findings providing an example of how different spectroscopic techniques can exhibit varying sensitivity to specific steps along the overall reaction coordinate connecting reactants to photoproducts.
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Affiliation(s)
- Stuart
W. Crane
- Institute
of Photonics & Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, U.K.
| | - Malcolm Garrow
- Institute
of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Paul D. Lane
- Institute
of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Kate Robertson
- Institute
of Photonics & Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, U.K.
| | - Alex Waugh
- Institute
of Photonics & Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, U.K.
| | - Jack M. Woolley
- Department
of Physics, University of Warwick, Coventry CV4 7AL, U.K.
| | - Vasilios G. Stavros
- School
of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
| | - Martin J. Paterson
- Institute
of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Stuart J. Greaves
- Institute
of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
| | - Dave Townsend
- Institute
of Photonics & Quantum Sciences, Heriot-Watt
University, Edinburgh EH14 4AS, U.K.
- Institute
of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
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3
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McClung S, Abeygunewardane D, Matsika S, Weinacht T. Excited-state dynamics of o-nitrophenol studied with UV pump-VUV probe time-resolved photoelectron and photoion spectroscopy. J Chem Phys 2023; 158:144303. [PMID: 37061485 DOI: 10.1063/5.0146399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
Time-resolved photoionization measurements were performed on o-nitrophenol pumped with UV laser pulses at a central wavelength of 255 nm (4.9 eV) and probed with vacuum ultraviolet (VUV) pulses at 153 nm (8.1 eV). The photoelectron spectrum and time of flight mass spectrum for ions were recorded at each pump-probe delay. The measurements are interpreted with the aid of electronic structure calculations for both the neutral and ionic states. Evidence is found for the formation of a bicyclic intermediate followed by NO dissociation through a process of internal conversion and intersystem crossing. The combination of photoelectron and photoion spectroscopy, together with computational results, provides strong evidence of intersystem crossing that is difficult to establish with only a single technique.
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Affiliation(s)
- Samuel McClung
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
| | | | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Thomas Weinacht
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
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4
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Bejoy NB, Roy Chowdhury P, Patwari GN. Modulating the Roaming Dynamics for the NO Release in ortho-Nitrobenzenes. J Phys Chem Lett 2023; 14:2816-2822. [PMID: 36912644 DOI: 10.1021/acs.jpclett.3c00134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The dynamics of NO release upon photodissociation of nitroaromatic compounds is dependent on the nature of the interaction between the NO2 group and substituent in the ortho position. A bimodal (slow and fast) translational energy distribution of the NO photofragment indicates the presence of two distinct NO elimination channels. The slow-to-fast branching ratio for the NO release is regulated by the hydrogen bonding ability of the ortho substituent and follows the order [OH > NH2 > CH3 > OCH3], indicating that the intramolecular hydrogen bonding plays a pivotal role in NO release dynamics. Further, the topology of the triplet state potential energy surface acts as a doorway to the dissociation pathway switching between the roaming and nonroaming mechanisms, with hydrogen bonding substituents (OH and NH2) favoring the roaming mechanism.
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Affiliation(s)
- Namitha Brijit Bejoy
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Prahlad Roy Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - G Naresh Patwari
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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5
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Ultrafast Spectroscopies of Nitrophenols and Nitrophenolates in Solution: From Electronic Dynamics and Vibrational Structures to Photochemical and Environmental Implications. Molecules 2023; 28:molecules28020601. [PMID: 36677656 PMCID: PMC9866910 DOI: 10.3390/molecules28020601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/27/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Nitrophenols are a group of small organic molecules with significant environmental implications from the atmosphere to waterways. In this work, we investigate a series of nitrophenols and nitrophenolates, with the contrasting ortho-, meta-, and para-substituted nitro group to the phenolic hydroxy or phenolate oxygen site (2/3/4NP or NP-), implementing a suite of steady-state and time-resolved spectroscopic techniques that include UV/Visible spectroscopy, femtosecond transient absorption (fs-TA) spectroscopy with probe-dependent and global analysis, and femtosecond stimulated Raman spectroscopy (FSRS), aided by quantum calculations. The excitation-dependent (400 and 267 nm) electronic dynamics in water and methanol, for six protonated or deprotonated nitrophenol molecules (three regioisomers in each set), enable a systematic investigation of the excited-state dynamics of these functional "nanomachines" that can undergo nitro-group twisting (as a rotor), excited-state intramolecular or intermolecular proton transfer (donor-acceptor, ESIPT, or ESPT), solvation, and cooling (chromophore) events on molecular timescales. In particular, the meta-substituted compound 3NP or 3NP- exhibits the strongest charge-transfer character with FSRS signatures (e.g., C-N peak frequency), and thus, does not favor nitroaromatic twist in the excited state, while the ortho-substituted compound 2NP can undergo ESIPT in water and likely generate nitrous acid (HONO) after 267 nm excitation. The delineated mechanistic insights into the nitro-substituent-location-, protonation-, solvent-, and excitation-wavelength-dependent effects on nitrophenols, in conjunction with the ultraviolet-light-induced degradation of 2NP in water, substantiates an appealing discovery loop to characterize and engineer functional molecules for environmental applications.
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6
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Schuurman MS, Blanchet V. Time-resolved photoelectron spectroscopy: the continuing evolution of a mature technique. Phys Chem Chem Phys 2022; 24:20012-20024. [PMID: 35297909 DOI: 10.1039/d1cp05885a] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Time-resolved photoelectron spectroscopy (TRPES) has become one of the most widespread techniques for probing nonadiabatic dynamics in the excited electronic states of molecules. Furthermore, the complementary development of ab initio approaches for the simulation of TRPES signals has enabled the interpretation of these transient spectra in terms of underlying coupled electronic-nuclear dynamics. In this perspective, we discuss the current state-of-the-art approaches, including efforts to push femtosecond pulses into vacuum ultraviolet and soft X-ray regimes as well as the utilization of novel polarizations to use time-resolved optical activity as a probe of nonadiabatic dynamics. We close this perspective with a forward-looking prospectus on the new areas of application for this technique.
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Affiliation(s)
- Michael S Schuurman
- National Research Council of Canada, 100 Sussex Dr, Ottawa, ON, K1N 6B9, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie Dr, Ottawa, ON, Canada.
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7
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Cole-Filipiak NC, Troß J, Schrader P, McCaslin LM, Ramasesha K. Ultraviolet photodissociation of gas-phase iron pentacarbonyl probed with ultrafast infrared spectroscopy. J Chem Phys 2021; 154:134308. [PMID: 33832268 DOI: 10.1063/5.0041074] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It is well known that ultraviolet photoexcitation of iron pentacarbonyl results in rapid loss of carbonyl ligands leading to the formation of coordinatively unsaturated iron carbonyl compounds. We employ ultrafast mid-infrared transient absorption spectroscopy to probe the photodissociation dynamics of gas-phase iron pentacarbonyl following ultraviolet excitation at 265 and 199 nm. After photoexcitation at 265 nm, our results show evidence for sequential dissociation of iron pentacarbonyl to form iron tricarbonyl via a short-lived iron tetracarbonyl intermediate. Photodissociation at 199 nm results in the prompt production of Fe(CO)3 within 0.25 ps via several energetically accessible pathways. An additional 15 ps time constant extracted from the data is tentatively assigned to intersystem crossing to the triplet manifold of iron tricarbonyl or iron dicarbonyl. Mechanisms for formation of iron tetracarbonyl, iron tricarbonyl, and iron dicarbonyl are proposed and theoretically validated with one-dimensional cuts through the potential energy surface as well as bond dissociation energies. Ground state calculations are computed at the CCSD(T) level of theory and excited states are computed with EOM-EE-CCSD(dT).
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Affiliation(s)
- Neil C Cole-Filipiak
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - Jan Troß
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - Paul Schrader
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - Laura M McCaslin
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - Krupa Ramasesha
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
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8
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Nitta Y, Schalk O, Igarashi H, Wada S, Tsutsumi T, Saita K, Taketsugu T, Sekikawa T. Real-Time Probing of an Atmospheric Photochemical Reaction by Ultrashort Extreme Ultraviolet Pulses: Nitrous Acid Release from o-Nitrophenol. J Phys Chem Lett 2021; 12:674-679. [PMID: 33393788 DOI: 10.1021/acs.jpclett.0c03297] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Photolysis of o-nitrophenol, contained in brown carbon, is considered to be a major process for the generation of nitrous acid (HONO) in the atmosphere. In this Letter, we used time-resolved photoelectron spectroscopy with 29.5 eV probe pulses and ab initio calculations to disentangle all reaction steps from the excitation to the dissociation of HONO. After excitation, intersystem crossing to the triplet manifold follows ultrafast excited-state intramolecular hydrogen transfer, where the molecules deplanarizes and finally splits off HONO after 0.5-1 ps.
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Affiliation(s)
- Yuki Nitta
- Department of Applied Physics, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
| | - Oliver Schalk
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Hironori Igarashi
- Department of Applied Physics, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
| | - Satoi Wada
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Takuro Tsutsumi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Kenichiro Saita
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Tetsuya Taketsugu
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Kita-ku, Sapporo, Hokkaido 001-0021, Japan
| | - Taro Sekikawa
- Department of Applied Physics, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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9
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Kotsina N, Townsend D. Improved insights in time-resolved photoelectron imaging. Phys Chem Chem Phys 2021; 23:10736-10755. [DOI: 10.1039/d1cp00933h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review new light source developments and data analysis considerations relevant to the time-resolved photoelectron imaging technique. Case studies illustrate how these themes may enhance understanding in studies of excited state molecular dynamics.
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Affiliation(s)
- Nikoleta Kotsina
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Dave Townsend
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
- Institute of Chemical Sciences
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10
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Paterson MJ, Townsend D. Rydberg-to-valence evolution in excited state molecular dynamics. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1815389] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | - Dave Townsend
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, UK
- Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh, UK
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11
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Kotsina N, Candelaresi M, Saalbach L, Zawadzki MM, Crane SW, Sparling C, Townsend D. Short-wavelength probes in time-resolved photoelectron spectroscopy: an extended view of the excited state dynamics in acetylacetone. Phys Chem Chem Phys 2020; 22:4647-4658. [DOI: 10.1039/d0cp00068j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved photoelectron spectroscopy using a vacuum ultraviolet probe brings new insight to the excited state dynamics operating in acetylacetone.
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Affiliation(s)
- Nikoleta Kotsina
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Marco Candelaresi
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Lisa Saalbach
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | | | - Stuart W. Crane
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Chris Sparling
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Dave Townsend
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
- Institute of Chemical Sciences
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12
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Warne EM, Downes-Ward B, Woodhouse J, Parkes MA, Springate E, Pearcy PAJ, Zhang Y, Karras G, Wyatt AS, Chapman RT, Minns RS. Photodissociation dynamics of methyl iodide probed using femtosecond extreme ultraviolet photoelectron spectroscopy. Phys Chem Chem Phys 2020; 22:25695-25703. [DOI: 10.1039/d0cp03478a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Femtosecond pump–probe photoelectron spectroscopy measurements using an extreme ultraviolet probe have been made on the photodissociation dynamics of UV (269 nm) excited CH3I.
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Affiliation(s)
- Emily M. Warne
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | | | - Joanne Woodhouse
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | | | - Emma Springate
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | | | - Yu Zhang
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Gabriel Karras
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Adam S. Wyatt
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | | | - Russell S. Minns
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
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13
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Jhang WR, Lai HY, Lin YC, Lee C, Lee SH, Lee YY, Ni CK, Tseng CM. Triplet vs πσ* state mediated N–H dissociation of aniline. J Chem Phys 2019; 151:141101. [DOI: 10.1063/1.5121350] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Wan Ru Jhang
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Hsin Ying Lai
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yen-Cheng Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Chin Lee
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Shih-Huang Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yin-Yu Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chi-Kung Ni
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chien-Ming Tseng
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
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14
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Zobel JP, González L. Nonadiabatic Dynamics Simulation Predict Intersystem Crossing in Nitroaromatic Molecules on a Picosecond Time Scale. CHEMPHOTOCHEM 2019; 3:833-845. [PMID: 31681833 PMCID: PMC6813632 DOI: 10.1002/cptc.201900108] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 05/06/2019] [Indexed: 12/19/2022]
Abstract
Previous time-resolved spectroscopic experiments and static quantum-chemical calculations attributed nitronaphthalene derivatives one of the fastest time scales for intersystem crossing within organic molecules, reaching the 100 fs mark. Nonadiabatic dynamics simulations on three nitronaphthalene derivatives challenge this view, showing that the experimentally observed ∼100 fs process corresponds to internal conversion in the singlet manifolds. Intersystem crossing, instead, takes place on a longer time scale of ∼1 ps. The dynamics simulations further reveal that the spin transitions occur via two distinct pathways with different contribution for the three systems, which are determined by electronic factors and the torsion of the nitro group. This study, therefore, indicates that the existence of sub-picosecond intersystem crossing in other nitroaromatic molecules should be questioned.
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Affiliation(s)
- J. Patrick Zobel
- Division of Theoretical Chemistry, KemicentrumLund UniversityP.O. Box 124SE-221 00LundSweden
| | - Leticia González
- Institute of Theoretical ChemistryUniversity of ViennaWähringer Straße 17A-1090ViennaAustria
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