Floppy modes and relaxation in GexSe1-x glasses

Floppy modes and relaxation processes in the GexSe1-x glasses system are studied by vibrational methods. We reporL Raman spectral line shapes over a temperature range from 100 to 300 K. Normalized frequency shifts with temperature of the GeSe4/2 breathing mode and the Se-Se stretching mode depend on the Ge composition. The results are associated with the stiffness transition window in which we suggest a radical decrease of Se-n (n > 2) segments which could be regarded as the microscopic origin of floppy modes in the Se-containing network glasses. (C) 2003 Published by Elsevier B.V.