Infrared absorption spectra of LiF and NaF crystals depending on the conditions of crystal growth and radiation treatment

Abstract

This work is devoted to studies of the efficiency of creation and diversity of molecular complexes with the strong hydrogen bond OHF in γ-irradiated LiF and NaF crystals depending on the type of magnesium-hydroxyl impurity complexes. Infrared (IR) spectroscopy studies have shown that the concentration of Mg2+OH¯OH¯Vc¯ complexes increases as the percentage of magnesium added to the melt increases. Increase in the concentration of Mg2+ OH¯OH¯Vc ¯complexes leads to increase in the intensity of the IR bands in the region of 3550–3700 cm–1 in unirradiated crystals. As a result, the radiation-induced IR bands of complexes with a strong hydrogen bond in the range of 1600–2400 cm−1 are shifted towards lower frequencies. The radiation-induced IR bands of complexes with strong hydrogen bond OHF in the region of 1600–2400 cm−1 are shifted towards high frequencies in the presence of a hydroxyl impurity in the crystal in the form of “free” OH¯ ions with the absorption band at νmax = 3730 cm-1. Such shifts also occur at different irradiation doses.