FORMATION OF AN S-2(-) MOLECULAR ION AND ITS LUMINESCENCE CHARACTERISTICS IN KCL-MNS CRYSTALS

It was found that when a KCl crystal doubly doped with a trace of MnS was irradiated with UV light, the S-2(-) molecular ions were effective ly produced through a photochemical reaction. These S-2(-) molecular i ons exhibited characteristic vibronic luminescence composed of zero-ph onon lines and phonon-side bands below 160 K. Such a vibronic structur e related to zero-phonon lines could also be observed for the first ti me in the luminescence excitation band. From the analysis of the spect ral positions of zero-phonon lines in the emission and excitation spec tra, the average vibrational frequencies of the S-2(-) molecular ion i n the ground state and excited state were determined to be 1.78 x 10(1 3) s(-1) and 1.13 x 10(13) s(-1) respectively.