0000000000365387
AUTHOR
Patrice Jacques
Ultrafast decay of the excited singlet states of thioxanthone by internal conversion and intersystem crossing.
The experimental ultrafast photophysics of thioxanthone in several aprotic organic solvents at room temperature is presented, measured using femtosecond transient absorption together with high-level ab initio CASPT2 calculations of the singlet- and triplet-state manifolds in the gas phase, including computed state minima and conical intersections, transition energies, oscillator strengths, and spin-orbit coupling terms. The initially populated singlet pi pi* state is shown to decay through internal conversion and intersystem crossing processes via intermediate n pi* singlet and triplet states, respectively. Two easily accessible conical intersections explain the favorable internal conversio…
A butterfly like motion as a clue to the photophysics of thioxanthone
Abstract A theoretical, quantum-chemical study of the thioxanthone (TX) molecule has been performed at the MP2 and CASPT2 levels of theory. Geometries, absorption energies, and transition and state properties have been investigated. Two conformers have been found very close in energy with planar (P) and non-planar (NP) structures, the latter characterized by a dihedral angle θ = 173.3° representing the bend of the side benzene rings and an out-of-plane angle ϕ = 4° of the C O bond. Large changes in the relative positions and properties of the two low-lying electronic absorption bands, ππ * and nπ * , are computed when changing the conformation. As a consequence of the analysis of the TX a…