Conical Intersection Passages of Molecules Probed by X‑ray Diffraction and Stimulated Raman Spectroscopy
Conical intersections (CoIns) play an important role in ultrafast relaxation channels. Their monitoring remains a formidable experimental challenge. We theoretically compare the probing of the S2 → S1 CoIn passage in 4-thiouracil by monitoring its vibronic coherences, using off-resonant X-ray-stimul...
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Published in | The journal of physical chemistry letters Vol. 12; no. 51; pp. 12300 - 12309 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
30.12.2021
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Subjects | |
Online Access | Get full text |
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Summary: | Conical intersections (CoIns) play an important role in ultrafast relaxation channels. Their monitoring remains a formidable experimental challenge. We theoretically compare the probing of the S2 → S1 CoIn passage in 4-thiouracil by monitoring its vibronic coherences, using off-resonant X-ray-stimulated Raman spectroscopy (TRUECARS) and time-resolved X-ray diffraction (TRXD). The quantum nuclear wavepacket (WP) dynamics provides an accurate picture of the photoinduced dynamics. Upon photoexcitation, the WP oscillates among the Franck–Condon point, the S2 minimum, and the CoIn with a 70 fs period. A vibronic coherence first emerges at 20 fs and can be observed until the S2 state is fully depopulated. The distribution of the vibronic frequencies involved in the coherence is recorded by the TRUECARS spectrogram. The TRXD signal provides spatial images of electron densities associated with the CoIn. In combination, the two signals provide a complementary picture of the nonadiabatic passage, which helps in the study of the underlying photophysics in thiobases. |
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Bibliography: | USDOE Office of Science (SC), Basic Energy Sciences (BES) FG02-04ER15571; SC0019484 |
ISSN: | 1948-7185 1948-7185 |
DOI: | 10.1021/acs.jpclett.1c03814 |