Radiationless decay of excited states of tetrahydrocannabinol through the S 1–S 0 (conical) intersection

Abstract

The ground and electronically excited singlet states of tetrahydrocannabinol have been studied theoretically using density functional and time-dependent density functional methods. The vertical excitation energies, the equilibrium geometries as well as the adiabatic excitation energies have been determined. Opening of the six-membered ring between the oxygen and carbon atoms has been considered as photochemical reaction path. This mechanism leads to a typical excited-state intramolecular hydrogen-transfer process and produces low-lying S 0–S 1 intersection (possible conical intersection, CI) which provides a channel for effective radiationless deactivation of the electronically excited state.