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Updated: May 29, 2026

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Ultrafast dynamics of UV-excited imidazole
Rachel Crespo-Otero1, Mario Barbatti, Hui Yu
1Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany. crespo@kofo.mpg.de
Abstract:
The ultrafast dynamics of UV-excited imidazole in the gas phase is investigated by theoretical nonadiabatic dynamics simulations and experimental time-resolved photoelectron spectroscopy. The results show that different electronic excited-state relaxation mechanisms occur, depending on the pump wavelength. When imidazole is excited at 239.6 nm, deactivation through the NH-dissociation conical intersection is observed on the sub-50 fs timescale. After 200.8 nm excitation, competition between NH-dissociation and NH-puckering conical intersections is observed. The NH-dissociation to NH-puckering branching ratio is predicted to be 21:4, and the total relaxation time is elongated by a factor of eight. A procedure for simulation of photoelectron spectra based on dynamics results is developed and employed to assign different features in the experimental spectra.
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