RESONANT RAMAN-SCATTERING OF RED-HGI2 IN B-EXCITON AND BAND-TO-BAND TRANSITION REGIONS

Our previous analysis of resonant Raman spectra in the A-exciton region of red-HgI2 at 4.2 K is extended to the wavelength range of the B-exciton and of the band-to-band transition. According to the grouptheoretical analysis and energy-momentum conservation laws, the present experimental results can give assignments of phonon modes in the second-order Raman processes. In the band-to-band transition region, we find multiple scattering of hot carriers by the E-mode phonons. One may give these new assignments of higher-order scattering processes for the first time in this layer-type semiconductor, thanks to improved spectral resolution. © 1979 The American Physical Society.