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Irradiation effects in CaF 2 probed by Raman scattering
Author(s) -
Alencar I.,
RuizFuertes J.,
Schwartz K.,
Trautmann C.,
Bayarjargal L.,
Haussühl E.,
Winkler B.
Publication year - 2016
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.4927
Subject(s) - fluence , raman spectroscopy , irradiation , raman scattering , laser , ion , analytical chemistry (journal) , saturation (graph theory) , spectroscopy , chemistry , materials science , optics , physics , mathematics , organic chemistry , chromatography , combinatorics , quantum mechanics , nuclear physics
The formation conditions and dynamics of Ca colloids and point defects that appear in irradiated single crystals of CaF 2 were investigated by Raman spectroscopy. The intensity changes in the Raman spectra because of the presence of different concentrations of point defects and Ca colloids that emerged in CaF 2 after irradiation with 2.2 GeV Au ions were used to study their distribution and stability under illumination with three laser wavelengths (473, 532 and 633 nm) at different output powers (2 to 200 mW). A damage saturation at a fluence of 6 × 10 11 ion cm −2 was observed. The dependence of the spectral changes on the ion fluence can be described by a core/halo damage cross‐section model. A radius of 13–18 nm was obtained for the outer (halo) cylinder, in agreement with previous swelling studies. Illuminations of irradiated samples with blue (473 nm) and green (532 nm) lasers were found to be extremely efficient in bleaching the samples, while illumination with a red (633 nm) laser did not lead to a sample recovery. This indicates that the bleaching process is governed by recombination of point defects that have to overcome an energy barrier. Typical time constants for the processes involved are presented. Copyright © 2016 John Wiley & Sons, Ltd.