1. Observation of Ultrafast Intersystem Crossing in Thymine by Extreme Ultraviolet Time-Resolved Photoelectron Spectroscopy
- Author
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Rolf H. Myhre, Thomas J. A. Wolf, Todd J. Martínez, Robert M. Parrish, Markus Gühr, Henrik Koch, Wolf, T. J. A., Parrish, R. M., Myhre, R. H., Martinez, T. J., Koch, H., and Guhr, M.
- Subjects
Population ,Photoionization ,010402 general chemistry ,01 natural sciences ,Molecular physics ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,0103 physical sciences ,ddc:530 ,Physical and Theoretical Chemistry ,education ,Excited state dynamic ,Settore CHIM/02 - Chimica Fisica ,education.field_of_study ,010304 chemical physics ,Photoprotection ,Relaxation (NMR) ,Institut für Physik und Astronomie ,Intersystem crossing ,Nucleobase ,0104 chemical sciences ,Thymine ,chemistry ,Excited state ,Ground state - Abstract
We studied the photoinduced ultrafast relaxation dynamics of the nucleobase thymine using gas-phase time-resolved photoelectron spectroscopy. By employing extreme ultraviolet pulses from high harmonic generation for photoionization, we substantially extend our spectral observation window with respect to previous studies. This enables us to follow relaxation of the excited state population all the way to low-lying electronic states including the ground state. In thymine, we observe relaxation from the optically bright (1)pi pi* state of thymine to a dark (1)n pi* state within 80 +/- 30 fs. The (1)n pi* state relaxes further within 3.5 +/- 0.3 ps to a low-lying electronic state. By comparison with quantum chemical simulations, we can unambiguously assign its spectroscopic signature to the (3)pi pi* state. Hence, our study draws a comprehensive picture of the relaxation mechanism of thymine including ultrafast intersystem crossing to the triplet manifold.
- Published
- 2019
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