Knowledge Bank

Theoretical considerations have shown that vibrational band shapes in isotropic media will he superpositions of Lorentzian. lines; however, in an anisotropic environment, non-Lorentzian band shapes are $predicted.1$ In order to test this theory, we have measured the reorientational lineshape of the $C\equiv N$ stretching vibration of the liquid crystal, 4-cyano-$4\prime$ -pentylbipbenyl (5CB), in its isotropic and nematic phases, The latter conveniently provides an anisotropic medium, Raman spectra in the 2220 $cm-1$ region, obtained above and below the phase transition temperature, will be presented and discussed.