CONFORMATION OF SURFACTANT MONOLAYERS AT SOLID LIQUID INTERFACES/

Infrared-visible sum-frequency (SFG) vibrational spectroscopy is used to study chain conformation of cationic surfactant monolayers (dioctad ecyl dimethyl ammonium chloride, DOAC), adsorbed at various quartz/liq uid interfaces at low coverage. The results show that the chains can a ssume many different conformations: an all-trans form if the liquid is alkane with a similarly long chain length, a bent form with significa nt trans-gauche defects if the liquid is CCL(4) or CDCL(3) or short-ch ain alkanes, and a highly contracted form if the liquid is water or al cohol.