Infrared determination of the orientation of molecules in stearamide monolayers

The orientation of molecules in the monomolecular stearamide monolayers has been studied by infrared linear dichroism. By comparing the transmission absorption spectra carried out at different angles of incidence with the reflection absorption spectra obtained by depositing the monolayers on a metal substrate, the orientation of the dipole transition moments for a great number of normal vibration modes of the molecules may be determined to within a few degrees accuracy. Given certain assumptions, the orientation of the molecules themselves can then be deduced.