It has been found that the high frequency longitudinal optical (LO) mode in vitreous SiO2 can be observed in the diffuse reflectance spectra of bulk glass or powder compacts. The sensitivity to this mode arises because of the off-normal components of reflectance which are collected in the diffuse reflectance spectra. The frequency and intensity of the mode are only approximately determined, however, and Kramers-Kronig transformation of specular reflectivity data is required to calculate precisely the mode location and intensity. The significance of this finding is that, in contrast to the use of infrared reflectance or Raman spectroscopy, where polished bulk specimens or single crystals are required, the present approach permits the determination of LO modes with with powder.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry