Integral Characteristics of Vibronic–Spin–Orbit Interactions in a Phosphorus-Containing Analogue of the Fluorene Molecule

Abstract

The strengths (P00s)2 and FVSO2 of the transitions from the triplet sublevels s = z, y, and x of the electronic state 3A″ of the phenyldibenzophosphole (DB(P-Ph)) molecule are calculated taking into account the intramolecular spin-orbit (SO) and joint vibronic-spin-orbit (VSO) interactions. The contributions to the vibronic transition strengths from the SO interactions in different structural elements of the molecule (the C atoms of the dibenzene framework, the P atom, and the Ph substituent) are determined. The effect of the nonplanar nuclear configuration of the DB(P-Ph) molecule on the values of FVSOs is investigated. The radiative deactivation rate constants of the krads triplet sublevels Ts are estimated. It is found that the vibrations of the A′(B1) symmetry in the fine-structure phosphorescence spectrum of DB(P-Ph) occur due to both the SO coupling exclusively in the P atom and the Tx → S0 transition (the x axis is perpendicular to the planar dibenzene framework of the molecule) with a high (preferential) population of this triplet sublevel.