Raman spectroscopy of LB films and monolayers at the air-water interface

Unenhanced Raman spectroscopy has so far been very rarely applied for studying monolayer organization although this method should in principle bring very rich molecular information. Moreover it is probably one of the most convenient technique for in-situ experiments, especially at the air-liquid interface. Recent technical developments (N-2-cooled CCD detector, notch holographic filter, confocal microscopy, etc.) have been implemented in our laboratory in order to design an ultrasensitive Raman spectrometer able to study a single monolayer deposited on a solid substrate or spread at the air-water interface. Test Raman spectra concerning mainly hydrogenated and deuterated cadmium arachidate multi- and monolayers deposited on a CaF2 plate and a monolayer spread at the air-water interface are presented. Finally all these results are gathered and discussed in terms of molecular organization and hydrocarbon chain packing in the monolayer.