Formation Time of STE at ¹Σ_u⁺ State in RbBr and KI under Pulsed Electron Beam in Picosecond Range

Abstract

The growth times (τ_σ^g) of the σ emission intensity in RbBr and KI crystals have been obtained to be 10±10 ps and 5±5 ps, respectively, under irradiation of a pulsed electron beam with the pulse duration of about 18 ps near liquid helium temperature. τ_σ^g includes both the life time of the conduction electron and the relaxation time of electrons from the conduction band down to the ¹Σ_u⁺(σ_u, 2sσ_g) state of the self trapped exciton. τ_σ^g is discussed in connection with the formation mechanism of the F-H center pair. The decay times (τ_σ^d) of the emission intensity in these crystals are 3.3±0.1 ns and 1.6±0.1 ns, respectively, in good agreement with those observed by using a pulsed proton beam with nsec pulse duration by Blair et al.