Optical detection of nuclear spin polarization via cross relaxation in A p-dibromobenzene single crystal

Abstract

Spin polarization of 81Br ( I = 3 2 ) nuclei is achieved via cross relaxation between electronic spins of the excited triplet state of a quinoxaline guest molecule and nuclei on neighbouring molecules in a p-dibromobenzene host crystal. The cross relaxation rate is of the order of 10 6 s −1 and is driven by the intermolecular hyperfine interaction. Additionally, NQR transitions have been induced in the single ground state and have been optically detected by means of an optical pumping cycle involving nuclear spin polarization.