Photodissociation dynamics in the first absorption band of pyrrole. II. Photofragment distributions for the 1A2(πσ*)←X̃1A1(ππ) transition

Abstract

The analysis of the total kinetic energy release (TKER) of the photofragments pyrrolyl + H-atom formed in the photodissociation of pyrrole in the low-lying state A(πσ*) is presented. The TKER distributions contain complementary and often more precise information on the fragmentation process than the broad diffuse absorption spectra. The distributions are calculated quantum mechanically for the diabatic state A(πσ*) either isolated or coupled to the ground electronic state at an exit channel conical intersection. The calculations use the novel ab initio quasi-diabatic potential energy matrix constructed in the work of Picconi and Grebenshchikov [J. Chem. Phys. 148, 104103 (2018)]. The approximate overlap integral-based adiabatic mapping approach is introduced with which the quantum mechanical TKER distributions can be efficiently and accurately reproduced. Finally, the calculated TKERs are compared with the experimental results. The main features of the measured vibrationally resolved distributions are reproduced, and the spectral peaks are assigned and interpreted in detail.

Can Hydrated Electrons be Produced from Water with Visible Light?

“…The kinetic energy distributions of H-atoms photodetached from pyrrole, phenol, indole, thiophenol, etc., were extensively investigated with velocity map imaging, multimass ion imaging, Rydberg tagging and femtosecond spectroscopy experiments, see [55][56][57][58][59][60] for representative examples. These experimen- tal studies were supported by ab initio calculations of the relevant PE surfaces and by calculations of the nonadiabatic time-dependent quantum wave-packet dynamics, e. g. [61][62][63][64][65][66][67] or quasi-classical trajectory surface-hopping simulations, e. g.. [68][69][70][71][72][73] For phenol•••(NH 3 ) n , phenol•••(H 2 O) n and pyrrole•••(NH 3 ) n complexes, it was experimentally established that PCET from photoexcited pyrrole or phenol to the solvent molecules is the dominant process, [74][75][76][77] rather than proton transfer, as previously thought. [78,79] The shape of the diffuse σ* orbital located on the NH group of HzH is similar to the shape of the σ* orbitals of pyrrole, phenol and indole.…”

Quantum mechanical study of the attosecond nonlinear Fourier transform spectroscopy of carbon dioxide

“…This expression is akin to the photodissociation matrix element 87 which contains the dynamical information on the dissociation process. 88,89 The above expression is applied to the ionizing system, and the projection on φ + f ψ e k | additionally specifies that the ejected photoelectron leaves with the energy E k .…”

Simulation of the dynamics of vibrationally mediated photodissociation for deuterated pyrrole

“…The photoprotection mechanism in DNA uses nonadiabatic transitions to prevent damage of DNA molecules from UVA and UVB light, which would otherwise result in mutations leading to cancer and other genetic deformations. Pyrrole is a key building block that is present in a large number of these biological molecules, including DNA and chlorophyll, and the dynamics of its photodissociation (along with electron impact dissociation) has been a subject of extensive experimental [1][2][3][4][5][6][7][8][9][10][11][12][13] and theoretical [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] studies.…”