The role of rotational relaxation in the intersystem crossing between a triplet and a singlet electronic state

Abstract

A calculation of the rate of ISC (intersystem crossing) relaxation at 0 K requires a knowledge of the spin-orbit coupling and the vibrational overlap integrals (Franck-Condon factors) between the T 1 and S 0 states. At elevated temperatures, the population of the rotational states needs to be taken into account through the overlap of the rotational wavefunctions between the interacting T 1 /S 0 electronic states. Here, we discuss the effect of the ISC singlet-triplet selection rules on the number and magnitude of the rotational overlap factors for the J ¼ 0, 5, and 10 rotational levels of thiophosgene, Cl 2 CS. Of equal importance is the influence of the spin-spin and spinrotation coupling on the rotational fragmentation factors and the ISC survival probability.

Ionic Liquid Dependence of Triplet-Sensitized Photon Upconversion

“…The third mechanism is based on spin-rotational coupling (SRC), which is an interaction between the magnetic moment generated by the rotational motion of a solute molecule and the magnetic moment of its electronic spins. , As theoretically proposed, SRC becomes significant as a triplet molecule rotates faster, and thus the relaxation of the T 1 state is considered to become quicker as η decreases.…”