PHOTOELECTROPOLING OF AZOBENZENE CHROMOPHORES IN MOLECULAR FILMS

The photoinduced reorientation and photoelectropoling processes were i nvestigated in molecular films of aliphatically substituted azobenzene s. While polarized illumination leads to a conversion of isotropic sam ples into anisotropic ones, upon application of external electric fiel ds even macroscopically polar materials are created. The macroscopic p olarity can be reversed under suitable experimental conditions. Order parameters as a function of the poling field were determined by Stark spectroscopy. Using atomic force microscopy it is shown that the struc ture of the sample is well defined on a microscopic length scale, wher eas on a macroscopic length scale it is not.