US EPA

1171557 

Journal Article 

Raman and Brillouin scattering studies on liquids and solids using an ultra high resolution spectrometer 

Sarma, LP; Gowd, TN 

2000 

Yes 

Indian Journal of Pure and Applied Physics
ISSN: 0019-5596 

38 

5 

335-343 

English 

WOS:000165240200010 

Use of a state of the art ultra high resolution spectrometer (0.04 cm(-1)) for both Raman and Brillouin scattering studies on liquids and solids has been reported. The spectrometer calibrated with mercury lines has been standardized by resolving the isotopes of chlorine in the vl Raman mode of carbon tetrachloride (CCl4). The spectra of Doppler shift:ed Brillouin doublers and central Rayleigh line for some molecular liquids; carbon tetrachloride (CCl4), ultra pure water (H2O), ethanol (C2H5OH), methanol (CH3OH). propanol ((CH3)(2)CHOH), methylbutane ((CH3)(2)CH.CH.CH3), amylacetate (CH3 COOC5H11), hydrogen peroxide (H2O2) and in natural minerals; hydrous quartz (SiO2.nH(2)O) and gypsum (CaSO4.2H(2)O) have been recorded and presented. The results demonstrate that the Brillouin doublets and the central Rayleigh line have been well resolved For their line shift, intensity and background. Sound velocities (VI) and sound absorption (I-R/2I(B)) calculated from the Brillouin shift and the integrated intensities of the Rayleigh and Brillouin doublets are compared with the available published data. The discrepancies between the measured V and I-R/2I(B) (Landau and Placzek ratio) and those reported in the literature have been attributed mainly to velocity dispersion and thermodynamic dispersion respectively. In some of the liquids, a considerable part of the total intensity has been found to be in the background under the Rayleigh- Brillouin components indicating the presence of new mode. Further spectral analysis are in progress to identify these modes. From these measurements, the authors found that the ultrahigh resolution spectrometer is unique for carrying out Raman, Brillouin and Rayleigh scattering studies on liquids and solids alike.