LOW WAVE-NUMBER RAMAN-SCATTERING IN VISCOUS-LIQUIDS

Low-wavenumber depolarized Raman spectra (-400 to 400 cm(-1)) for diox ane, water aod glycerol are presented. Stokes aod anti-Stokes spectra (-400 to 400 cm(-1)) are used to define a reduced spectrum, in which t he effects of temperature and also flat backgrounds and symmetric cent ral components are removed, without knowledge of these parameters. Com parison with the usual reductions shows that (i) all inelastically sca ttered photons must be considered as 'true' Raman signals, due to proc esses involving Boson-like excitations, (ii) if central scattering exi sts, then its intensity also depends on the population factor, (iii) t he low-wavenumber Stokes signal is more intense than expected for a fa ctor of n + 1 only, owing to non-linear effects, and (iv) the systemat ic use of reduced spectra is not essential, and can be hazardous in so me cases.