Here you will find all scientific publications from the group leader, Daniel Horke. Articles and materials written for a more general audience can be found on the Outreach pages. Recent posters from the group are in the gallery!
Filter Publications:
2024
10.
Abma G L, Parkes M A, Razmus W O, Zhang Y, Wyatt A S, Springate E, Chapman R T, Horke D A, Minns R S
Direct Observation of a Roaming Intermediate and Its Dynamics Journal Article
In: J. Am. Chem. Soc., vol. 146, no. 18, pp. 12595-12600, 2024.
Links | BibTeX | Altmetric | Tags: dynamics, experimental design, HHG, intramolecular interactions, Non-adiabatic dynamics, Photoelectron spectroscopy
@article{doi:10.1021/jacs.4c01543,
title = {Direct Observation of a Roaming Intermediate and Its Dynamics},
author = {Grite L. Abma and Michael A. Parkes and Weronika O. Razmus and Yu Zhang and Adam S. Wyatt and Emma Springate and Richard T. Chapman and Daniel A. Horke and Russell S. Minns},
doi = {10.1021/jacs.4c01543},
year = {2024},
date = {2024-04-29},
urldate = {2024-04-29},
journal = {J. Am. Chem. Soc.},
volume = {146},
number = {18},
pages = {12595-12600},
keywords = {dynamics, experimental design, HHG, intramolecular interactions, Non-adiabatic dynamics, Photoelectron spectroscopy},
pubstate = {published},
tppubtype = {article}
}
2021
9.
Warne E M, Smith A D, Horke D A, Springate E, Jones A J H, Cacho C, Chapman R T, Minns R S
Time Resolved Detection of the S(1D) Product of the UV Induced Dissociation of CS2 Journal Article
In: J. Chem. Phys., vol. 154, no. 3, pp. 034302, 2021, ISSN: 0021-9606, 1089-7690.
Abstract | Links | BibTeX | Altmetric | Tags: Coincidence Imaging, dynamics, HHG, Non-adiabatic dynamics, Photoelectron spectroscopy
@article{Warne:J.Chem.Phys.154:034302,
title = {Time Resolved Detection of the S(1D) Product of the UV Induced Dissociation of CS2},
author = {Emily M. Warne and Adam D. Smith and Daniel A. Horke and Emma Springate and Alfred J. H. Jones and Cephise Cacho and Richard T. Chapman and Russell S. Minns},
url = {http://aip.scitation.org/doi/10.1063/5.0035045},
doi = {10.1063/5.0035045},
issn = {0021-9606, 1089-7690},
year = {2021},
date = {2021-01-01},
urldate = {2021-06-21},
journal = {J. Chem. Phys.},
volume = {154},
number = {3},
pages = {034302},
abstract = {The products formed following the photodissociation of UV (200 nm) excited CS2 are monitored in a time resolved photoelectron spectroscopy experiment using femtosecond XUV (21.5 eV) photons. By spectrally resolving the electrons, we identify separate photoelectron bands related to the CS2 + h$nu$ textrightarrow S(1D) + CS and CS2 + h$nu$ textrightarrow S(3P) + CS dissociation channels, which show different appearance and rise times. The measurements show that there is no delay in the appearance of the S(1D) product contrary to the results of Horio et al. [J. Chem. Phys. 147, 013932 (2017)]. Analysis of the photoelectron yield associated with the atomic products allows us to obtain a S(3P)/S(1D) branching ratio and the rate constants associated with dissociation and intersystem crossing rather than the effective lifetime observed through the measurement of excited state populations alone.},
keywords = {Coincidence Imaging, dynamics, HHG, Non-adiabatic dynamics, Photoelectron spectroscopy},
pubstate = {published},
tppubtype = {article}
}
The products formed following the photodissociation of UV (200 nm) excited CS2 are monitored in a time resolved photoelectron spectroscopy experiment using femtosecond XUV (21.5 eV) photons. By spectrally resolving the electrons, we identify separate photoelectron bands related to the CS2 + h$nu$ textrightarrow S(1D) + CS and CS2 + h$nu$ textrightarrow S(3P) + CS dissociation channels, which show different appearance and rise times. The measurements show that there is no delay in the appearance of the S(1D) product contrary to the results of Horio et al. [J. Chem. Phys. 147, 013932 (2017)]. Analysis of the photoelectron yield associated with the atomic products allows us to obtain a S(3P)/S(1D) branching ratio and the rate constants associated with dissociation and intersystem crossing rather than the effective lifetime observed through the measurement of excited state populations alone.
2018
8.
Smith A D, Warne E M, Bellshaw D, Horke D A, Tudorovskya M, Springate E, Jones A J H, Cacho C, Chapman R T, Kirrander A, Minns R S
Mapping the Complete Reaction Path of a Complex Photochemical Reaction Journal Article
In: Phys. Rev. Lett., vol. 120, no. 18, pp. 183003, 2018.
Abstract | Links | BibTeX | Altmetric | Tags: Coincidence Imaging, dynamics, HHG, Non-adiabatic dynamics, Photoelectron spectroscopy
@article{Smith:Phys.Rev.Lett.120:183003,
title = {Mapping the Complete Reaction Path of a Complex Photochemical Reaction},
author = {Adam D. Smith and Emily M. Warne and Darren Bellshaw and Daniel A. Horke and Maria Tudorovskya and Emma Springate and Alfred J. H. Jones and Cephise Cacho and Richard T. Chapman and Adam Kirrander and Russell S. Minns},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.120.183003},
doi = {10.1103/PhysRevLett.120.183003},
year = {2018},
date = {2018-05-01},
urldate = {2019-01-24},
journal = {Phys. Rev. Lett.},
volume = {120},
number = {18},
pages = {183003},
abstract = {We probe the dynamics of dissociating CS2 molecules across the entire reaction pathway upon excitation. Photoelectron spectroscopy measurements using laboratory-generated femtosecond extreme ultraviolet pulses monitor the competing dissociation, internal conversion, and intersystem crossing dynamics. Dissociation occurs either in the initially excited singlet manifold or, via intersystem crossing, in the triplet manifold. Both product channels are monitored and show that, despite being more rapid, the singlet dissociation is the minor product and that triplet state products dominate the final yield. We explain this by a consideration of accurate potential energy curves for both the singlet and triplet states. We propose that rapid internal conversion stabilizes the singlet population dynamically, allowing for singlet-triplet relaxation via intersystem crossing and the efficient formation of spin-forbidden dissociation products on longer timescales. The study demonstrates the importance of measuring the full reaction pathway for defining accurate reaction mechanisms.},
keywords = {Coincidence Imaging, dynamics, HHG, Non-adiabatic dynamics, Photoelectron spectroscopy},
pubstate = {published},
tppubtype = {article}
}
We probe the dynamics of dissociating CS2 molecules across the entire reaction pathway upon excitation. Photoelectron spectroscopy measurements using laboratory-generated femtosecond extreme ultraviolet pulses monitor the competing dissociation, internal conversion, and intersystem crossing dynamics. Dissociation occurs either in the initially excited singlet manifold or, via intersystem crossing, in the triplet manifold. Both product channels are monitored and show that, despite being more rapid, the singlet dissociation is the minor product and that triplet state products dominate the final yield. We explain this by a consideration of accurate potential energy curves for both the singlet and triplet states. We propose that rapid internal conversion stabilizes the singlet population dynamically, allowing for singlet-triplet relaxation via intersystem crossing and the efficient formation of spin-forbidden dissociation products on longer timescales. The study demonstrates the importance of measuring the full reaction pathway for defining accurate reaction mechanisms.
2017
7.
Bellshaw D, Horke D A, Smith A D, Watts H M, Jager E, Springate E, Alexander O, Cacho C, Chapman R T, Kirrander A, Minns R S
Ab-Initio Surface Hopping and Multiphoton Ionisation Study of the Photodissociation Dynamics of CS2 Journal Article
In: Chem. Phys. Lett., vol. 683, pp. 383–388, 2017, ISSN: 0009-2614.
Abstract | Links | BibTeX | Altmetric | Tags: dynamics, Non-adiabatic dynamics, Photoelectron spectroscopy, velocity-map imaging
@article{Bellshaw:Chem.Phys.Lett.683:383,
title = {Ab-Initio Surface Hopping and Multiphoton Ionisation Study of the Photodissociation Dynamics of CS2},
author = {Darren Bellshaw and Daniel A. Horke and Adam D. Smith and Hannah M. Watts and Edward Jager and Emma Springate and Oliver Alexander and Cephise Cacho and Richard T. Chapman and Adam Kirrander and Russell S. Minns},
url = {http://www.sciencedirect.com/science/article/pii/S0009261417301744},
doi = {10.1016/j.cplett.2017.02.058},
issn = {0009-2614},
year = {2017},
date = {2017-09-01},
urldate = {2019-01-24},
journal = {Chem. Phys. Lett.},
volume = {683},
pages = {383--388},
series = {Ahmed Zewail (1946-2016) Commemoration Issue of Chemical Physics Letters},
abstract = {New ab initio surface hopping simulations of the excited state dynamics of CS2 including spin-orbit coupling are compared to new experimental measurements using a multiphoton ionisation probe in a photoelectron spectroscopy experiment. The calculations highlight the importance of the triplet states even in the very early time dynamics of the dissociation process and allow us to unravel the signatures in the experimental spectrum, linking the observed changes to both electronic and nuclear degrees of freedom within the molecule.},
keywords = {dynamics, Non-adiabatic dynamics, Photoelectron spectroscopy, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
New ab initio surface hopping simulations of the excited state dynamics of CS2 including spin-orbit coupling are compared to new experimental measurements using a multiphoton ionisation probe in a photoelectron spectroscopy experiment. The calculations highlight the importance of the triplet states even in the very early time dynamics of the dissociation process and allow us to unravel the signatures in the experimental spectrum, linking the observed changes to both electronic and nuclear degrees of freedom within the molecule.
2016
6.
Smith A D, Watts H M, Jager E, Horke D A, Springate E, Alexander O, Cacho C, Chapman R T, Minns R S
Resonant Multiphoton Ionisation Probe of the Photodissociation Dynamics of Ammonia Journal Article
In: Phys. Chem. Chem. Phys., vol. 18, no. 40, pp. 28150–28156, 2016.
Abstract | Links | BibTeX | Altmetric | Tags: dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging
@article{Smith:Phys.Chem.Chem.Phys.18:28150,
title = {Resonant Multiphoton Ionisation Probe of the Photodissociation Dynamics of Ammonia},
author = {Adam D Smith and Hannah M Watts and Edward Jager and Daniel A Horke and Emma Springate and Oliver Alexander and Cephise Cacho and Richard T Chapman and Russell S Minns},
url = {http://pubs.rsc.org/en/content/articlehtml/2016/cp/c6cp05279g},
doi = {10.1039/C6CP05279G},
year = {2016},
date = {2016-10-01},
journal = {Phys. Chem. Chem. Phys.},
volume = {18},
number = {40},
pages = {28150--28156},
abstract = {The dissociation dynamics of the ~A-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.},
keywords = {dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
The dissociation dynamics of the ~A-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.
2013
5.
Horke D A, Li Q, Blancafort L A, Verlet J R R
Ultrafast Above-Threshold Dynamics of the Radical Anion of a Prototypical Quinone Electron-Acceptor Journal Article
In: Nature Chem., vol. 5, no. 8, pp. 711–717, 2013.
Links | BibTeX | Altmetric | Tags: dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging
@article{Horke:NatureChem.5:711,
title = {Ultrafast Above-Threshold Dynamics of the Radical Anion of a Prototypical Quinone Electron-Acceptor},
author = {Daniel A Horke and Quansong Li and Llu A Blancafort and Jan R R Verlet},
url = {http://dx.doi.org/10.1038/nchem.1705},
doi = {10.1038/nchem.1705},
year = {2013},
date = {2013-09-01},
urldate = {2013-09-01},
journal = {Nature Chem.},
volume = {5},
number = {8},
pages = {711--717},
keywords = {dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
4.
Mooney C R S, Horke D A, Chatterley A S, Simperler A, Fielding H H, Verlet J R R
Taking the Green Fluorescence out of the Protein: Dynamics of the Isolated GFP Chromophore Anion Journal Article
In: Chem. Sci., vol. 4, no. 3, pp. 921, 2013.
Links | BibTeX | Altmetric | Tags: Anion spectroscopy, dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging
@article{Mooney:Chem.Sci.4:921,
title = {Taking the Green Fluorescence out of the Protein: Dynamics of the Isolated GFP Chromophore Anion},
author = {Ciar\'{a}n R S Mooney and Daniel A Horke and Adam S Chatterley and Alexandra Simperler and Helen H Fielding and Jan R R Verlet},
url = {http://xlink.rsc.org/?DOI=c2sc21737f},
doi = {10.1039/c2sc21737f},
year = {2013},
date = {2013-01-01},
journal = {Chem. Sci.},
volume = {4},
number = {3},
pages = {921},
keywords = {Anion spectroscopy, dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
2012
3.
Chatterley A S, Horke D A, Verlet J R R
On the Intrinsic Photophysics of Indigo: A Time-Resolved Photoelectron Spectroscopy Study of the Indigo Carmine Dianion Journal Article
In: Phys. Chem. Chem. Phys., vol. 14, no. 46, pp. 16155, 2012.
Links | BibTeX | Altmetric | Tags: Anion spectroscopy, dynamics, Photoelectron spectroscopy, polyanions, velocity-map imaging
@article{Chatterley:Phys.Chem.Chem.Phys.14:16155,
title = {On the Intrinsic Photophysics of Indigo: A Time-Resolved Photoelectron Spectroscopy Study of the Indigo Carmine Dianion},
author = {Adam S Chatterley and Daniel A Horke and Jan R R Verlet},
url = {http://xlink.rsc.org/?DOI=c2cp43275g},
doi = {10.1039/c2cp43275g},
year = {2012},
date = {2012-01-01},
journal = {Phys. Chem. Chem. Phys.},
volume = {14},
number = {46},
pages = {16155},
keywords = {Anion spectroscopy, dynamics, Photoelectron spectroscopy, polyanions, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
2011
2.
Horke D A, Verlet J R R
Time-Resolved Photoelectron Imaging of the Chloranil Radical Anion: Ultrafast Relaxation of Electronically Excited Electron Acceptor States Journal Article
In: Phys. Chem. Chem. Phys., vol. 13, no. 43, pp. 19546–19552, 2011.
Abstract | Links | BibTeX | Altmetric | Tags: Anion spectroscopy, dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging
@article{Horke:Phys.Chem.Chem.Phys.13:19546,
title = {Time-Resolved Photoelectron Imaging of the Chloranil Radical Anion: Ultrafast Relaxation of Electronically Excited Electron Acceptor States},
author = {Daniel A Horke and Jan R R Verlet},
url = {http://xlink.rsc.org/?DOI=c1cp22237f},
doi = {10.1039/c1cp22237f},
year = {2011},
date = {2011-01-01},
journal = {Phys. Chem. Chem. Phys.},
volume = {13},
number = {43},
pages = {19546--19552},
abstract = {The spectroscopy and dynamics of near-threshold excited states of the isolated chloranil radical anion are investigated using photoelectron imaging. The photoelectron images taken at 480 nm clearly indicate resonance-enhanced photodetachment via a bound electronic excited state. Time-resolved photoelectron imaging reveals that the excited state rapidly decays on a timescale of 130 fs via internal conversion. The ultrafast relaxation dynamics of excited states near threshold are pertinent to common electron acceptor molecules based on the quinone moiety and may serve as doorway states that enable efficient electron transfer in the highly exergonic inverted regime, despite the presence of large free energy barriers.},
keywords = {Anion spectroscopy, dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
The spectroscopy and dynamics of near-threshold excited states of the isolated chloranil radical anion are investigated using photoelectron imaging. The photoelectron images taken at 480 nm clearly indicate resonance-enhanced photodetachment via a bound electronic excited state. Time-resolved photoelectron imaging reveals that the excited state rapidly decays on a timescale of 130 fs via internal conversion. The ultrafast relaxation dynamics of excited states near threshold are pertinent to common electron acceptor molecules based on the quinone moiety and may serve as doorway states that enable efficient electron transfer in the highly exergonic inverted regime, despite the presence of large free energy barriers.
2010
1.
Roberts G M, Lecointre J, Horke D A, Verlet J R R
Spectroscopy and Dynamics of the 7,7,8,8-Tetracyanoquinodimethane Radical Anion. Journal Article
In: Phys. Chem. Chem. Phys., vol. 12, no. 23, pp. 6226–6232, 2010.
Abstract | Links | BibTeX | Altmetric | Tags: Anion spectroscopy, dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging
@article{Roberts:Phys.Chem.Chem.Phys.12:6226,
title = {Spectroscopy and Dynamics of the 7,7,8,8-Tetracyanoquinodimethane Radical Anion.},
author = {Gareth M Roberts and Julien Lecointre and Daniel A Horke and Jan R R Verlet},
url = {http://dx.doi.org/10.1039/c001438a},
doi = {10.1039/c001438a},
year = {2010},
date = {2010-01-01},
journal = {Phys. Chem. Chem. Phys.},
volume = {12},
number = {23},
pages = {6226--6232},
abstract = {The photoelectron spectrum of the 7,7,8,8-tetracyanoquinodimethane (TCNQ) radical anion has been measured at 3.1 eV. Additionally, the ultrafast relaxation dynamics of the first excited state (1(2)B(3u)) of TCNQ(-) have been studied using time-resolved photoelectron spectroscopy, which reveals that it undergoes internal conversion back to the ground state ((2)B(2g)) with an associated lifetime of 650 fs and shows evidence of coherent nuclear motion. From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. - Roberts, Gareth M; Lecointre, Julien; Horke, Daniel a; Verlet, Jan R R ) From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. - Roberts, Gareth M; Lecointre, Julien; Horke, Daniel a; Verlet, Jan R R ) From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. - Roberts, Gareth M; Lecointre, Julien; Horke, Daniel a; Verlet, Jan R R ) From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. - Roberts, Gareth M; Lecointre, Julien; Horke, Daniel A; Verlet, Jan R R )},
keywords = {Anion spectroscopy, dynamics, Non-adiabatic dynamics, photoelectron imaging, Photoelectron spectroscopy, velocity-map imaging},
pubstate = {published},
tppubtype = {article}
}
The photoelectron spectrum of the 7,7,8,8-tetracyanoquinodimethane (TCNQ) radical anion has been measured at 3.1 eV. Additionally, the ultrafast relaxation dynamics of the first excited state (1(2)B(3u)) of TCNQ(-) have been studied using time-resolved photoelectron spectroscopy, which reveals that it undergoes internal conversion back to the ground state ((2)B(2g)) with an associated lifetime of 650 fs and shows evidence of coherent nuclear motion. From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. – Roberts, Gareth M; Lecointre, Julien; Horke, Daniel a; Verlet, Jan R R ) From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. – Roberts, Gareth M; Lecointre, Julien; Horke, Daniel a; Verlet, Jan R R ) From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. – Roberts, Gareth M; Lecointre, Julien; Horke, Daniel a; Verlet, Jan R R ) From Duplicate 1 ( Spectroscopy and dynamics of the 7,7,8,8-tetracyanoquinodimethane radical anion. – Roberts, Gareth M; Lecointre, Julien; Horke, Daniel A; Verlet, Jan R R )