Evidence of STE emission in low temperature thermoluminescence of pure KClUV-irradiated at 15K

Thermoluminescence spectral measurements in the 20-250 K range were made is nominally pure KCl crystals irradiated at 15 K with 203, 230 and 270 nm UV light. Two spectral regions are clearly distinguished for the irradiation wavelengths used. The luminescence in the 300-400 nm interval (region I) ha s been suggested to be intrinsic impurity related emission bands. The emiss ion in the 400-600 nm interval (region II) shows characteristics (position, band width and temperature dependence) very similar to the pi-polarjzed pe rturbed self-trapped exciton luminescence band or to the electron-V-K cente r recombination luminescence. Additionally, for irradiation with 203 nm lig ht the spectral emission shows a deep valley with minimum around 540 nm in the 85-100 K temperature range, which has been previously associated to the self-absorption due to F centers in the crystal.