Slit-Function Corrections Applied to Laser-Excited Raman Bands of Liquids

Abstract

The use of small spectral slitwidths complicates Raman intensity measurements of laser-excited spectra. The nature of the slit-function correction in medium-resolution laser-Raman instruments is discussed and some effects of asymmetric slit functions on asymmetric and symmetric Raman bands are explored. Corrections to bandwidth and band shape for nonideal slit functions are obtained from the concept of an intermediate standard which represents the pure slit function at some limiting spectral slitwidth. The corrections are applied to the contours of the Raman bands of CCl₄ at 458 cm⁻¹ and CH₃OH at 1028 cm⁻¹, and the corrected contour of the 1028-cm⁻¹ band is compared to that obtained for the same band on a high-resolution laser-Raman spectrometer. A codification of Raman band shapes by means of two shape parameters is discussed.