抄録
In additively colored KCl crystals containing sodium, irradiation in the F-band causes its complete conversion in two absorption bands which are termed A1 and A2. By investigating their thermal, photochemical, and dichroic properties, these two bands are found to arise from a common species of centers called A-centers, and are identified with Petroff’s A- and B-bands which have been found in nominally pure specimens. From the analysis of dichroic spectra, peak energy and half-width are determined for each band at several temperatures. The observed oscillator strength is 0.90 for the A1-band and 0.81 for the A2-band. The A-centers are destroyed thermally with an activation energy 0.43 eV. A model is proposed for the A-center that it consists of an F-center having a sodium ion as a nearest neighbor to the vacancy. A calculation of energy levels by the method of molecular orbitals is presented.
