1
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Champenois EG, List NH, Ware M, Britton M, Bucksbaum PH, Cheng X, Centurion M, Cryan JP, Forbes R, Gabalski I, Hegazy K, Hoffmann MC, Howard AJ, Ji F, Lin MF, Nunes JPF, Shen X, Yang J, Wang X, Martinez TJ, Wolf TJA. Femtosecond Electronic and Hydrogen Structural Dynamics in Ammonia Imaged with Ultrafast Electron Diffraction. PHYSICAL REVIEW LETTERS 2023; 131:143001. [PMID: 37862660 DOI: 10.1103/physrevlett.131.143001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 07/06/2023] [Accepted: 08/12/2023] [Indexed: 10/22/2023]
Abstract
Directly imaging structural dynamics involving hydrogen atoms by ultrafast diffraction methods is complicated by their low scattering cross sections. Here we demonstrate that megaelectronvolt ultrafast electron diffraction is sufficiently sensitive to follow hydrogen dynamics in isolated molecules. In a study of the photodissociation of gas phase ammonia, we simultaneously observe signatures of the nuclear and corresponding electronic structure changes resulting from the dissociation dynamics in the time-dependent diffraction. Both assignments are confirmed by ab initio simulations of the photochemical dynamics and the resulting diffraction observable. While the temporal resolution of the experiment is insufficient to resolve the dissociation in time, our results represent an important step towards the observation of proton dynamics in real space and time.
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Affiliation(s)
- Elio G Champenois
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Nanna H List
- Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Matthew Ware
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Mathew Britton
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Philip H Bucksbaum
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Xinxin Cheng
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Martin Centurion
- Department of Physics and Astronomy, University of Nebraska Lincoln, Lincoln, Nebraska 68588, USA
| | - James P Cryan
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Ruaridh Forbes
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Ian Gabalski
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Kareem Hegazy
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | | | - Andrew J Howard
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Fuhao Ji
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Ming-Fu Lin
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J Pedro F Nunes
- Department of Physics and Astronomy, University of Nebraska Lincoln, Lincoln, Nebraska 68588, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Jie Yang
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Todd J Martinez
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Thomas J A Wolf
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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2
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Recio P, Cachón J, Zanchet A, Marggi Poullain S, Bañares L. Photodissociation dynamics of methylamine in the blue edge of the A-band. I. The H-atom elimination channel. J Chem Phys 2023; 158:234304. [PMID: 37326159 DOI: 10.1063/5.0152993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/30/2023] [Indexed: 06/17/2023] Open
Abstract
The photodissociation dynamics of methylamine (CH3NH2) upon excitation in the blue edge of the first absorption A-band, in the 198-203 nm range, are investigated by means of nanosecond pump-probe laser pulses and velocity map imaging combined with H(2S)-atom detection through resonance enhanced multiphoton ionization. The images and corresponding translational energy distributions for the H-atoms produced show three different contributions associated with three reaction pathways. The experimental results are complemented by high-level ab initio calculations. The potential energy curves computed as a function of the N-H and C-H bond distances allow us to draw a picture of the different mechanisms. Major dissociation occurs through N-H bond cleavage and it is triggered by an initial geometrical change, i.e., from a pyramidal configuration of the C-NH2 with respect to the N atom to a planar geometry. The molecule is then driven into a conical intersection (CI) seam where three outcomes can take place: first, threshold dissociation into the second dissociation limit, associated with the formation of CH3NH(Ã), is observed; second, direct dissociation after passage through the CI leading to the formation of ground state products; and third, internal conversion into the ground state well in advance to dissociation. While the two last pathways were previously reported at a variety of wavelengths in the 203-240 nm range, the former had not been observed before to the best of our knowledge. The role of the CI and the presence of an exit barrier in the excited state, which modify the dynamics leading the two last mechanisms, are discussed considering the different excitation energies used.
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Affiliation(s)
- Pedro Recio
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Javier Cachón
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Alexandre Zanchet
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain
| | - Sonia Marggi Poullain
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Luis Bañares
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), Cantoblanco, 28049 Madrid, Spain
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3
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Svoboda V, Wang C, Waters MDJ, Wörner HJ. Electronic and vibrational relaxation dynamics of NH3 Rydberg states probed by vacuum-ultraviolet time-resolved photoelectron imaging. J Chem Phys 2019; 151:104306. [DOI: 10.1063/1.5116707] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Vít Svoboda
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Chuncheng Wang
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Max D. J. Waters
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Hans Jakob Wörner
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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4
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Intersystem crossing dynamics in singly substituted thiouracil studied by time-resolved photoelectron spectroscopy: Micro-environmental effects due to sulfur position. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.08.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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5
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Mai S, Mohamadzade A, Marquetand P, González L, Ullrich S. Simulated and Experimental Time-Resolved Photoelectron Spectra of the Intersystem Crossing Dynamics in 2-Thiouracil. Molecules 2018; 23:E2836. [PMID: 30388739 PMCID: PMC6278540 DOI: 10.3390/molecules23112836] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/25/2018] [Accepted: 10/26/2018] [Indexed: 11/16/2022] Open
Abstract
We report time-dependent photoelectron spectra recorded with a single-photon ionization setup and extensive simulations of the same spectra for the excited-state dynamics of 2-thiouracil (2TU) in the gas phase. We find that single-photon ionization produces very similar results as two-photon ionization, showing that the probe process does not have a strong influence on the measured dynamics. The good agreement between the single-photon ionization experiments and the simulations shows that the norms of Dyson orbitals allow for qualitatively describing the ionization probabilities of 2TU. This reasonable performance of Dyson norms is attributed to the particular electronic structure of 2TU, where all important neutral and ionic states involve similar orbital transitions and thus the shape of the Dyson orbitals do not strongly depend on the initial neutral and final ionic state. We argue that similar situations should also occur in other biologically relevant thio-nucleobases, and that the time-resolved photoelectron spectra of these bases could therefore be adequately modeled with the techniques employed here.
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Affiliation(s)
- Sebastian Mai
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria.
| | - Abed Mohamadzade
- Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
| | - Philipp Marquetand
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria.
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria.
| | - Susanne Ullrich
- Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
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6
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Yu H, Sanchez-Rodriguez JA, Pollum M, Crespo-Hernández CE, Mai S, Marquetand P, González L, Ullrich S. Internal conversion and intersystem crossing pathways in UV excited, isolated uracils and their implications in prebiotic chemistry. Phys Chem Chem Phys 2018; 18:20168-76. [PMID: 27189184 DOI: 10.1039/c6cp01790h] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The photodynamic properties of molecules determine their ability to survive in harsh radiation environments. As such, the photostability of heterocyclic aromatic compounds to electromagnetic radiation is expected to have been one of the selection pressures influencing the prebiotic chemistry on early Earth. In the present study, the gas-phase photodynamics of uracil, 5-methyluracil (thymine) and 2-thiouracil-three heterocyclic compounds thought to be present during this era-are assessed in the context of their recently proposed intersystem crossing pathways that compete with internal conversion to the ground state. Specifically, time-resolved photoelectron spectroscopy measurements evidence femtosecond to picosecond timescales for relaxation of the singlet (1)ππ* and (1)nπ* states as well as for intersystem crossing to the triplet manifold. Trapping in the excited triplet state and intersystem crossing back to the ground state are investigated as potential factors contributing to the susceptibility of these molecules to ultraviolet photodamage.
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Affiliation(s)
- Hui Yu
- Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
| | | | - Marvin Pollum
- Department of Chemistry and Center for Chemical Dynamics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Carlos E Crespo-Hernández
- Department of Chemistry and Center for Chemical Dynamics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sebastian Mai
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Philipp Marquetand
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Susanne Ullrich
- Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
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7
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Sánchez-Rodríguez JA, Mohamadzade A, Mai S, Ashwood B, Pollum M, Marquetand P, González L, Crespo-Hernández CE, Ullrich S. 2-Thiouracil intersystem crossing photodynamics studied by wavelength-dependent photoelectron and transient absorption spectroscopies. Phys Chem Chem Phys 2017. [DOI: 10.1039/c7cp02258a] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The excitation-wavelength dependence of the intersystem crossing (ISC) dynamics of 2-thiouracil was studied in gas-phase and solution.
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Affiliation(s)
| | - Abed Mohamadzade
- Department of Physics and Astronomy
- University of Georgia
- Athens
- USA
| | - Sebastian Mai
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- Währinger Straße 17
- Austria
| | - Brennan Ashwood
- Department of Chemistry and Center for Chemical Dynamics
- Case Western Reserve University
- 10900 Euclid Avenue
- Cleveland
- USA
| | - Marvin Pollum
- Department of Chemistry and Center for Chemical Dynamics
- Case Western Reserve University
- 10900 Euclid Avenue
- Cleveland
- USA
| | - Philipp Marquetand
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- Währinger Straße 17
- Austria
| | - Leticia González
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- Währinger Straße 17
- Austria
| | - Carlos E. Crespo-Hernández
- Department of Chemistry and Center for Chemical Dynamics
- Case Western Reserve University
- 10900 Euclid Avenue
- Cleveland
- USA
| | - Susanne Ullrich
- Department of Physics and Astronomy
- University of Georgia
- Athens
- USA
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8
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Horke DA, Watts HM, Smith AD, Jager E, Springate E, Alexander O, Cacho C, Chapman RT, Minns RS. Hydrogen Bonds in Excited State Proton Transfer. PHYSICAL REVIEW LETTERS 2016; 117:163002. [PMID: 27792360 DOI: 10.1103/physrevlett.117.163002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 06/06/2023]
Abstract
Hydrogen bonding interactions between biological chromophores and their surrounding protein and solvent environment significantly affect the photochemical pathways of the chromophore and its biological function. A common first step in the dynamics of these systems is excited state proton transfer between the noncovalently bound molecules, which stabilizes the system against dissociation and principally alters relaxation pathways. Despite such fundamental importance, studying excited state proton transfer across a hydrogen bond has proven difficult, leaving uncertainties about the mechanism. Through time-resolved photoelectron imaging measurements, we demonstrate how the addition of a single hydrogen bond and the opening of an excited state proton transfer channel dramatically changes the outcome of a photochemical reaction, from rapid dissociation in the isolated chromophore to efficient stabilization and ground state recovery in the hydrogen bonded case, and uncover the mechanism of excited state proton transfer at a hydrogen bond, which follows sequential hydrogen and charge transfer processes.
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Affiliation(s)
- D A Horke
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - H M Watts
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - A D Smith
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - E Jager
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - E Springate
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - O Alexander
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - C Cacho
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - R T Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - R S Minns
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
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9
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Smith AD, Watts HM, Jager E, Horke DA, Springate E, Alexander O, Cacho C, Chapman RT, Minns RS. Resonant multiphoton ionisation probe of the photodissociation dynamics of ammonia. Phys Chem Chem Phys 2016; 18:28150-28156. [PMID: 27722319 DOI: 10.1039/c6cp05279g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dissociation dynamics of the Ã-state of ammonia have been studied using a resonant multiphoton ionisation probe in a photoelectron spectroscopy experiment. The use of a resonant intermediate in the multiphoton ionisation process changes the ionisation propensity, allowing access to different ion states when compared with equivalent single photon ionisation experiments. Ionisation through the E' 1A1' Rydberg intermediate means we maintain overlap with the ion state for an extended period, allowing us to monitor the excited state population for several hundred femtoseconds. The vibrational states in the photoelectron spectrum show two distinct timescales, 200 fs and 320 fs, that we assign to the non-adiabatic and adiabatic dissociation processes respectively. The different timescales derive from differences in the wavepacket trajectories for the two dissociation pathways that resonantly excite different vibrational states in the intermediate Rydberg state. The timescales are similar to those obtained from time resolved ion kinetic energy release measurements, suggesting we can measure the different trajectories taken out to the region of conical intersection.
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Affiliation(s)
- Adam D Smith
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
| | - Hannah M Watts
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
| | - Edward Jager
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
| | - Daniel A Horke
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Emma Springate
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, UK
| | - Oliver Alexander
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, UK
| | - Cephise Cacho
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, UK
| | - Richard T Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, UK
| | - Russell S Minns
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
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10
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Klein LB, Thompson JOF, Crane SW, Saalbach L, Sølling TI, Paterson MJ, Townsend D. Ultrafast relaxation dynamics of electronically excited piperidine: ionization signatures of Rydberg/valence evolution. Phys Chem Chem Phys 2016; 18:25070-25079. [DOI: 10.1039/c6cp04494h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved photoelectron spectroscopy reveals distinct ionization signatures of Rydberg-to-valence state evolution in the secondary aliphatic amine piperidine.
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Affiliation(s)
- Liv B. Klein
- Department of Chemistry
- University of Copenhagen
- DK-2100 Copenhagen
- Denmark
| | | | - Stuart W. Crane
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Lisa Saalbach
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | - Theis I. Sølling
- Department of Chemistry
- University of Copenhagen
- DK-2100 Copenhagen
- Denmark
| | | | - Dave Townsend
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
- Institute of Chemical Sciences
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