We present Raman spectra of four semiconductor doped glasses and a sin
gle crystal of CdS0.55Se0.45 in the range 30-800 cm(-1) in the backsca
ttering geometry. This includes the first-order Raman scattering from
the disorder-activated zone-edge phonons and the LO phonons. TO phonon
modes are not observed, as in bulk CdS, for the excitation well above
the lowest gap. We show that the asymmetric line profile of the LO ph
onon structure can be understood as a composite of two phonon modes: t
he zone center and the zone edge phonons. Disorder-activated modes in
the (30-130)-cm(-1) range and the higher-order Raman spectra are also
observed and found to be consistent with this assignment.