ODMR of relaxed excited states of interstitial atomic hydrogen centres in alkali halides

Abstract

Optically detected magnetic resonance (ODMR) experiments were performed on interstitial atomic hydrogen centres in mixed configuration in RbCl and RbBr doped with I⁻, and RbCl doped with Br⁻, H₁°(I, Br) centres. In RbCl/I the ODMR of a relaxed excited state with resolved proton hyperfine and I superhyperfine interaction was measured. The state is a spin quartet due to parallel spins at H⁻ and I° with a large zero field splitting similar to what was found previously for KC1/I⁻. This state has also a fluorescence emission with τ = 370 nsec. In RbBr/I⁻ a metastable nonradiating relaxed excited state was found with an ODMR spectrum due to an I° hole interacting with 2 Br neighbours along (110) (lifetime >20 msec) which tunnels back into the H_i°(I) centre. In RbCl/Br⁻no relaxed excited state was found. Upon excitation the H_i°(Br⁻) centres decay into H_s ⁻ and Cl_2,S ⁻ centres.