<title>Indirect free-exciton luminescence in AgCl</title>

Abstract

Indirect free-exciton luminescence in AgC1 single crystal accompanied by TO(L) phonon emission is found for the first time at 382.9 nm (3.238 eV) at 2 K for picosecond pulse laser excitation at 351 nm (3.53 eV).The luminescence decay curve monitored at 382.9 nm has a fast decay component, 20 ps, which is interpreted as the selftrapping time of holes generated at the L point. A luminescence band peaking at 385 nm(3.221 eV) is found, which is assigned as due to the optical transition from a point around the exit of the quantum mechanical tunneling process through the self-trapping potential barrier. The rise time 70 ps is interpreted as the time required for tunneling. A luminescence band peaking at 386.5 nm (3.208 eV) is found and assigned to be due to excitons bound by shallow impurity.

Excitonic hopping-pinning scenarios in lithium niobate based on atomistic models: different kinds of stretched exponential kinetics in the same system

“…The exciton hopping activation energy is apparently larger than any energy barrier involved in the original localization of free excitons leading to their self-trapping. For the original self-trapping of holes in AgCl an energy barrier of only 1.7 meV was estimated by Kobayasi et al [52]. A similar thermalization process of hot electrons in LN was found at RT to occur on the 100 femtosecond scale [29,53]; as highest phonon frequencies in LN are in the 20 THz range [3,54], this excludes thermalization barriers larger than a few tens of meV.…”