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Optical Absorption of LiF Crystals Irradiated with Neutrons at Liquid Nitrogen Temperature
Author(s) -
Kamikawa T.,
Kazumata Y.,
Ozawa K.
Publication year - 1966
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19660140221
Subject(s) - liquid nitrogen , irradiation , materials science , absorption band , annealing (glass) , absorption (acoustics) , neutron , doping , absorption spectroscopy , analytical chemistry (journal) , optics , optoelectronics , chemistry , nuclear physics , physics , organic chemistry , chromatography , composite material
The effects of low temperature neutron irradiation on LiF single crystals are investigated by optical absorption measurements. The crystals are irradiated and measurements made at 80°K. In the spectra obtained at 77°K, the V k ‐ and M‐bands appear prominently but the F‐band is hidden under other overlapping bands. A noticeable band found at 578 nm is suggested to be associated with the Li interstitials. During thermal annealing, three absorption peaks are observed at 415, 430, and 443 nm in the M‐band region. The new band at 415 nm shows a fine structure at 77°K. A new absorption band at 545 nm, called the S‐band, is observed to increase in thermally bleached crystals after ageing at room temperature. The experiments on doped crystals show that the divalent cation modify the characteristics of low temperature neutron irradiation. In the doped crystals, the 578 nm band due to the Li interstitials is not observed. When a very large band at about 400 nm is partially bleached, many sharp lines are observed. Their origin is discussed briefly.