Wavenumber versus temperature plots

Figure 7. Wavenumber versus temperature plot for the CH2 asymmetric C-H stretching band in the 2916 to 2925 cm l region of desiccated, hairless mouse stratum corneum spectra during heating and cooling cycle.

The state of order or fluidity of the acyl chains of amphiphilic molecules is known to be a characteristic property of each membrane lipid, and was analyzed by FTIR using the peak position of Vs(CH2). In Fig. 1, the phase transition behavior of the acyl chains of lipid A is presented, as a plot of the peak position of Vs(CH2) versus temperature. It can be seen from the change in the wavenumber values, that in the presence of the peptide only a slight shift to lower wavenumbers, and a concomitant increase in the phase transition temperature Tc takes place. This corresponds to a slight rigidification of the lipid A acyl chains. 

Up to a density of about 1.0 g cm the vibrational intensity is found to be independent of the temperature and the density (or pressure). At the highest densities, B (6700-7300) slightly decreases. This behavior, which is also observed in several other near-infrared bands of CO2 (Buback et al., 1986a, 1986b), seems to indicate that repulsive interactions are becoming important in highly compressed fluid CO2. This assumption is supported by an inspection of the density dependence of the band maximum positions. In Fig. 6.2-12, the wavenumbers of maximum absorption in the P and the R branch, i>p(max) and i> (max), of the component around 4980 cm (see Fig. 6.2-8) are plotted versus the density. The arithmetic mean values of the P and R branch maxima, i> , which are shown as full circles in the lower density spectra, linearly decrease with the density. They can be... 

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