Effect of impurities on the energies and damping of optical phonons in rhenium

In order to investigate the transition from the regime of the conservation of the wave vector of electron excitations that interact with lattice vibra tions to the regime controlled by collisions, temperature (5-300 K) depende nces of the spectra of Raman scattering by optical phonons were measured in rhenium alloys. At all the temperatures, a considerable softening of phono n energies was found, which was accompanied by a broadening of phonon lines and the appearance of asymmetry pointing to the interference effects in Ra man scattering from bound electron-phonon excitations. Comparison of the re sults thus obtained with the estimations of the contribution from the direc t effects due to the introduction of impurities and with the theoretical pr edictions suggests significant changes in the electron structure near the F ermi level and in the electron-phonon coupling.