Low-Temperature Optical Spectra and Zero-Phonon Transitions ofColor Centers in γ-Rayed Sodium Fluoride Crystals

A lot of narrow lines on R₂, R⁺, N₁, N^- and some other unknown centers have been observed in γ-rayed pure and doped sodium fluoride crystals in the temperature range of 9-77K. The proper laser irradiation was used for strengthening the zero-phonon lines and the relative explanation was given. The spectral properties and thermostabilities of the lines were investigated systeniaticitl1y at different temperatures.