Sudden structural change at an air/binary liquid interface: Sum frequency study of the air/acetonitrile-water interface

Abstract

We report the first observation of a sharp structural change in an air/acetonitrile-water interface as the solution composition varies; the abruptness of which suggests an interfacial phase transition. The structural change is manifested by shifts in the frequency and in the polarization of the signal from the acetonitrile molecules in the interface observed using infrared+visible surface sum frequency generation. © 1993 American Institute of Physics.