Distortions of the electric field gradient of 81Br near crystalline defect sites studied by enhanced optically detected NQR

Abstract

During an optical pumping cycle electron spin polarization achieved in the excited triplet state of quinoxaline in p-dibromobenzene was transferred to bromine nuclear spins in the disturbed surrounding shell via induced Δm s = 1, Δm I = 1 transitions and was thus stored in the singlet ground state. Subsequent depolarization by NQR allowed optical detection of 18Br (I = 3 2 ) in very low concentrations (1000 ppm).