In connection with indirect Raman di †erence spectroscopy, a method which has been suggested for measuring Raman wavenumber shifts between two di †erent samples with a multi-channel spectrometer, the behaviour of the calibration of the spectrometer with temperature changes was studied. The aim of this work was to determine the experimental conditions which must be respected when using a spectral lamp as a calibration reference to take into account the possible calibration drift due to temperature changes during the recordings. The e †ects of temperature oscillations about a constant value and also a long-lasting temperature change were measured for each operating mode of the dispersing system of the spectrometer. The extent to which a calibration shift due to a temperature change may be considered as constant from one end of the spectral Ðeld of the detector of the spectrometer to the other was also investigated.

In order to compare the molecular Raman spectra between an optically isotropic phase and an anisotropic phase, a method is proposed having especially in view the study of transitions in lyotropic surfactant systems. Its application to the transition between the isotropic and hexagonal phases in the water-a-octyl-w-hydroxypentakis (oxyethylene) system shows that there is no significant molecular structure change at transition. This result suggests that all the micelles in the L, phase in equilibrium with the hexagonal phase have a cylindrical shape.

A simplified method of calculation of the contour of a totally polarized Raman band for an asymmetric top molecule in the gaseous state has been applied to produce the first accurate band-shape calculation for the ν1 band of the water molecule. The good fits between computed and experimental contours from approximately 150 to 350 °C lay the foundation for temperature determination for water vapor from measurements of the Raman band profile and for density measurements independent of the temperature.

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