IN-SITU IMAGING OF LANGMUIR MONOLAYERS BY 2ND-HARMONIC MICROSCOPY

A simple second-harmonic microscope for in situ and real-time investig ation of interfaces and ultrathin films is described. A spot on the in terface is illuminated with a laser. The frequency-doubled light is us ed for imaging. The technique is surface specific. A single laser puls e is sufficient to create an image. Scanning of the sample with a shar ply focused laser beam is not required. Harmonic imaging reveals more information on surface order and symmetry than is possible with linear optical microscopy experiments. Polarization microscopy with uncrosse d polarizers is utilized as a linear optical technique. This simple me thod provides superior resolution compared with Brewster angle microsc opy.