Evidence forLBands in NaCl

Abstract

NaCl crystals are investigated in the spectral range 200-800 mμ by means of photostimulated thermoluminescence and differential-absorption-spectrum measurements. Four weak bands are found on the high-energy side of the $F$ band, which have the properties of $L$ bands: weak absorption coefficient, high and temperature-independent ionization efficiency, ionization intensity roughly proportional to the concentration of $F$ centers. Moreover, it is found that thermoluminescence is stimulated only by light absorbed by electron centers ($R, F, K, L$ bands), not by $V$ centers.