RESOLUTION OF INFRARED PROFILES FROM VARIABLE-TEMPERATURE EXPERIMENTSON MIXTURES AND CONFORMERS IN RAPID EQUILIBRIUM BY COMPENSATING FOR THERMAL AND SOLVENT EFFECTS

Curve resolution of infrared profiles from non-conformational mixtures and conformational equilibria is discussed. For successful resolution it is crucial that temperature and solvent induced variations observe d as peak shifts and band broadening are accounted for. As changes in absorbance (in IR) or intensities (in Raman) with temperature may be d ifferent for different bands of the same conformer, the resolution mus t be performed on local parts or the spectra. An assumption about temp erature independence of the integrated extinction coefficients in such a local region of the spectra must be made. The success of curve reso lution by compensating for thermal effects is largely determined by th e level of the experimental noise, the change in analyte concentration s with temperature and the thermal effects. Curve resolution of mixtur e spectra is illustrated using model spectra of toluene and cyclohexan e and variable temperature spectra of chlorocyclohexane.