Population of triplet states in acetophenone: A quantum dynamics perspective

This is the authors' abstract. We don't add key points for this paper.

When initially excited to its first singlet excited state, acetophenone, a prototypical aromatic ketone, is characterized by a singlet to triplet conversion quantum yield close to 100%. In this work, the time evolution of photo-excited acetophenone is theoretically investigated using quantum dynamics simulations based on the Multi Configuration Time Dependent Hartree (MCTDH) method. A model Hamiltonian, comprising both electronic and vibronic terms, is defined and its parameters are fitted to available data obtained by high-level quantum chemical calculations. An exploratory MCTDH dynamics shows a sequential mechanism S 1 /T 2 /T 1 . The population in the triplet manifold is distributed evenly among the two states, explaining the origin of acetophenone rich photochemistry. Initialement excit e vers son premier etat excit e singulet, l'ac etoph enone, une c etone aromatique typique, est caract eris ee par une conversion singulet vers triplet proche de 100%. Dans ce travail, l' evolution temporelle de l'ac etoph enone photo-excit ee est etudi ee de fa,on th eorique par dynamique quantique bas ee sur la m ethode Multi Configuration Time Dependent Hartree (MCTDH). Un Hamiltonien mod ele, comprenant des termes electroniques et vibroniques, est d efini et ses param etres sont d etermin es a partir de donn ees obtenues par des calculs de chimie quantique de haut niveau. La dynamique MCTDH exploratoire montre un m ecanisme s equentiel S 1 /T 2 /T 1 . La population est distribu ee egalement dans les deux etats triplet, expliquant l'origine de la photochimie riche de l'ac etoph enone.