INDUCED ABSORPTION BAND IN N REGION OF LIF CRYSTALS BY CHARGED PARTICLE IRRADIATION AT LIQUID NITROGEN TEMPERATURE

Single crystals of lithium fluoride have been irradiated with deuterons or protons at liquid nitrogen temperature. In absorption spectra of the crystals immediately after irradiation, a band is observed at 542 nm in addition to the F and M bands. This band has an almost constant intensity during warming from LNT to RT. It is obscured by the other overlapping bands when the crystal is heated above 100°C or when this is aged at RT for a long time. The nature of this band is examined in connection with the so-called N2 band, Farge's I band and Vander Lugt's Nc band. The following relation is believed to be most plausible: The observed absorption band is identified with the I band. The N2 band is identified with the Nc band but may not be identified with the I band. © 1969, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.