Ab Initio Molecular Dynamics and Time-Resolved Photoelectron Spectroscopy of Electronically Excited Uracil and Thymine

Abstract

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Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

“…2 shows no evidence for C 4 H 6 N 2 O + production. Accordingly, Nachtigallova et al [9] noted the absence of a ring-opening channel in the calculated relaxation dynamics of thymine following S 2 excitation [2]. The reasons for this specific difference compared with uracil were not discussed, although possible kinematic effects of the CH 3 group of thymine were mentioned in the context of more general differences in the excited molecules' relaxation pathways.…”

“…Time resolved pump-probe experiments [2] and calculations [3] on isolated molecules have yielded rich insights into their excited state dynamics, while studies of base pairs and hydrated clusters have enabled closer analogies to be drawn with cellular environments [4]. Internal conversion to the vibrationally hot electronic ground state (either directly or via S 1 states of mainly nπ* and σπ* character) dominates S 2 (ππ*) deactivation [5,6], although intersystem crossing to long-lived triplet states has also been identified [7,8].…”

Electronic Structure of Adenine and Thymine Base Pairs Studied by Femtosecond Electron−Ion Coincidence Spectroscopy

“…IVR may then be followed by crossing to the long-lived S 1 state on a ps time scale. 35 For the adenine-thymine base pair, molecular dynamics/ab initio studies predicted predominantly planar, hydrogen-bound structures. 36 However, the Watson-Crick (WC) structure was not the lowest energy structure and was also not identified in nanosecond IR-UV resonance-enhanced multiphoton ionization (REMPI) experiments in a supersonic jet expansion.…”

GPU-Accelerated State-Averaged Complete Active Space Self-Consistent Field Interfaced with Ab Initio Multiple Spawning Unravels the Photodynamics of Provitamin D3

“…[1][2][3][4][5] Furthermore, photochemical reactions occur under nonequilibrium conditions, typically on the femtosecond to picosecond timescale. [6][7] Although advances in ultrafast spectroscopy have enabled detailed studies of such reactions, 6 these experiments are not straightforward to perform and their results can be difficult to interpret. Theoretical methods provide an electronically and atomically-resolved model for photochemical processes, thus providing insight into phenomena that cannot be observed experimentally.…”