Robert Gaufrès

Variation of the polarizability with the nuclear configuration as studied by rayleigh scattering and rotational raman spectroscopy in H2S and D2S

Abstract Experimental evidence of a difference of optical anisotropy between H 2 S and D 2 S and a variation of the R ba ratio in the rotational Raman spectra of both molecules have been previously reported. A quantitative and consistent interpretation of these results is tentatively given on the ground of variations of the nuclear configuration due to the isotopic effect and/or the centrifugal distortion.

Phase transition in non-ionic surfactant—water systems as studied by Raman spectrometry: Part I. Water—α-octyl-ω-hydroxypentakis (oxyethylene)

Abstract The Raman spectra of α-octyl-ω- hydroxypentakis (oxyethylene) (C8E5) in water—(C8E5) systems have been studied for various compositions and at various temperatures. Continuous changes of the spectra are observed in the isotropic phase, when varying the composition, which is maximum when approaching the hexagonal phase boundary. The transition between the isotropic and hexagonal phases brings about an important change in the ν(CH) region. A tentative interpretation of these results is given.

Determination of shifts by means of the absolute area of the difference spectrum: cases of non-rigorous application of the theory

Abstract The method of determination of spectral shifts by use of the absolute area of the difference spectrum, previously developed in several papers, holds rigorously when the bands to be compared either have same profiles or are both symmetrical. It often happens in practice that none of these conditions is fulfilled and the concept itself of spectral shift is then questionable. However, it is possible to define in any case quantities, which, in the rigorous cases of definition of the spectral shift, are equal to each other and to the spectral shift. These quantities are the shift between the maximum intensity of the bands, the distance between vertical lines sharing the area of the bands into two equal parts, the displacement which must be given to one of the bands to reach the minimum of the absolute area of the difference spectrum. They are determined for a series of couples of model profiles, one of them being more and more dissymmetrical. Their values are compared with the approximate spectral shifts given by the application of the absolute area method. It is shown that up to relatively important dissimilarity of the profiles, the values of all these quantities are very close and may be taken as the spectral shift. Moreover, an extrapolation method giving the shift between the maximum intensities of dissimilar and dissymmetrical bands is given.