Abstract:
Raman scattering in the region 20 to 100 cm -1 for fused quartz,
"pyrex" boro-silicate glass, and soft soda-lime silicate glass was investigated.
The Raman spectra for the fused quartz and the pyrex glass were obtained at
room temperature using the 488 nm exciting line of a Coherent Radiation
argon-ion laser at powers up to 550 mW. For the soft soda-lime glass the
514.5 nm exciting line at powers up to 660 mW was used because of a weak
fluorescence which masked the Stokes Raman spectrum. In addition it is
demonstrated that the low-frequency Raman coupling constant can be
described by a model proposed by Martin and Brenig (MB). By fitting the
predicted spectra based on the model with a Gaussian, Poisson, and Lorentzian
forms of the correlation function, the structural correlation radius (SCR) was
determined for each glass. It was found that to achieve the best possible fit·
from each of the three correlation functions a value of the SCR between 0.80
and 0.90 nm was required for both quartz and pyrex glass but for the soft
soda-lime silicate glass the required value of the SCR. was between 0.50 and
0.60 nm .. Our results support the claim of Malinovsky and Sokolov (1986)
that the MB model based on a Poisson correlation function provides a
universal fit to the experimental VH (vertical and horizontal polarizations)
spectrum for any glass regardless of its chemical composition. The only
deficiency of the MB model is its failure to fit the experimental depolarization
spectra.
