Raman studies of the C=C and C=O stretching modes in various cholesteryl alkanoates

Cholesteryl alkanoates were previously mostly studied by biochemists, and more rarely by physicists. In this work we present Raman studies of the C=C and C=O stretching modes for various cholesteryl alkanoates after different treatments. The unicity of these bonds in theses molecules permits us to propound the C=C stretching mode as an internal reference in regard to its independence from the alkyl chain length. The splitting of the C=O stretching mode leads us to conclude on the existence of two types of molecules, differing only by angle and bond-length variations, in the polycrystalline state.