Molecular Orientation by Two-Photon Isomerization: Towards 3 Dimentional Orientation Storage

ZOUHEIR SEKKAT, MAKOTO MAEDA, HIDEKAZU ISHITOBI, and SATOSHI KAWATA

We present experimental evidence of two-photon photo-selection which is governed by a law in the fourth power of the cosine of the angle between the polarization of the excitation light and the two-photon transition dipole moment of the chromophore. We show that polarized two-photon excitation of photoisomerizable chromophores orients them in a nonpolar manner. We discuss the case of a diarylethene chromophore which is oriented by twophoton selective isomerization, and that of an azobenzene derivative which is selectively bleached by two-photon polarized excitation. The studies are done in thin films of poly(methylmethacrylate). We show that two-photon orientation exhibits birefringence under a reflection confocal microscope.