Energy storage and thermoluminescence in halogen doped solid xenon. III. Photodynamics of charge separation, self-trapping, and ion–hole recombination

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Abstract
The optically accessed excitonic charge transfer states of solid xenon doped with atomic halogens relax by one of two channels: self-trapping of the exciton to form the triatomic molecular exciplex, or self-trapping of the hole which leads to charge separation by the creation of a pair of oppositely charged small polarons. The latter channel leads to long term storage of optical energy. Charged pair storage densities of 1017 cm−3 are routinely realized, and retention times as long as 35 h have been directly verified. The trapped ion–hole pair may recombine either through tunneling or thermal activation of the self-trapped hole. Tunneling leads to temperature independent phosphorescence which decays with a hyperbolic time dependence. Temporally and spectrally resolved phosphorescence and thermoluminescence are used for the characterization of the trapped state energetics and their recombination dynamics. A first order kinetic treatment of the recombination kinetics yields 800(±200) cm−1 as the lattice relaxation energy for the self-trapped hole.