Electron–Phonon Interaction of Color Centers with a Zero-Phonon Line 436.55 nm in Crystals LiF–O, OH

The absorption spectra have been measured at temperatures of 7.2–300 K of a $\gamma$-irradiated and UV-exposed LiF crystal with an admixture of oxygen and hydroxyl. The coupling force (S) with the phonons of the lattice of the electronic–vibrational transition with the zero-phonon line 436.55 nm is determined from the ratio of the intensities of the zero-phonon line and the vibronic absorption band. Based on the value of S, the nature of the color center responsible for the absorption band of 390 nm and radiation of 490 nm is proposed.