TY  - JOUR
A1  - Wolf, Thomas J. A.
A1  - Parrish, Robert M.
A1  - Myhre, Rolf H.
A1  - Martinez, Todd J.
A1  - Koch, Henrik
A1  - Gühr, Markus
T1  - Observation of Ultrafast Intersystem Crossing in Thymine by Extreme Ultraviolet Time-Resolved Photoelectron Spectroscopy
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - 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.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.jpca.9b05573
SN  - 1089-5639
SN  - 1520-5215
VL  - 123
IS  - 32
SP  - 6897
EP  - 6903
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Myhre, Rolf H.
A1  - Wolf, Thomas J. A.
A1  - Cheng, Lan
A1  - Nandi, Saikat
A1  - Coriani, Sonia
A1  - Gühr, Markus
A1  - Koch, Henrik
T1  - A theoretical and experimental benchmark study of core-excited states in nitrogen
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - The high resolution near edge X-ray absorption fine structure spectrum of nitrogen displays the vibrational structure of the core-excited states. This makes nitrogen well suited for assessing the accuracy of different electronic structure methods for core excitations. We report high resolution experimental measurements performed at the SOLEIL synchrotron facility. These are compared with theoretical spectra calculated using coupled cluster theory and algebraic diagrammatic construction theory. The coupled cluster singles and doubles with perturbative triples model known as CC3 is shown to accurately reproduce the experimental excitation energies as well as the spacing of the vibrational transitions. The computational results are also shown to be systematically improved within the coupled cluster hierarchy, with the coupled cluster singles, doubles, triples, and quadruples method faithfully reproducing the experimental vibrational structure. Published by AIP Publishing.
Y1  - 2018
U6  - https://doi.org/10.1063/1.5011148
SN  - 0021-9606
SN  - 1089-7690
VL  - 148
IS  - 6
PB  - American Institute of Physics
CY  - Melville
ER  -