Orthorhombic structure of cadmium behenate monolayers on the water surfaceof a Langmuir trough detected by polarization modulation infrared spectroscopy

Polarization modulation infrared reflection absorption spectroscopy (PM-IRR AS) was applied to investigate the structure of behenic acid monolayers on the surface of aqueous Cd2+ sub-phase in a Langmuir trough at the room temp erature of 293 K. The PM-IRRAS spectra were recorded at representative poin ts throughout 0.401 similar to 0.100 nm(2) and the surface-pressure area is otherms were recorded during compression to these points. It is found that compressed cadmium behenate (CdB) monolayers possess an orthorhombic unit c ell. On the other hand, single monolayers of CdB deposited on CaF2 substrat es at 20 mN m(-1) possessed a triclinic parallel packing. (C) 2000 Elsevier Science B.V. All rights reserved.