STUDY OF INITIAL-STAGES OF F-CENTER AGGREGATION IN NACL BY RAMAN-SCATTERING

Raman spectra of F‐centres in NaCl are very dependent on colouration method. First‐order spectra of “isolated” F‐centres are very well interpreted when a 70 and 10% softening in the interionic force constant between the F‐centre and its 1 nn's and between its 1 nn's and 4 nn's, respectively, is considered and if the electron‐phonen interaction is extended up to the 5th ion shell. At the very initial stage of colloidal aggregate formation, the change of the Γ 1+ Raman spectrum may be interpreted assuming F‐centre clusters whose sizesare likely much smaller than the laser wavelength. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA