On the Nature of Photoinduced Optical Anisotropy in Diacetylene Langmuir-Blodgett Films

For the first time photoinduced molecular reorientation has been observed in diacetylene Langmuir-Blodgett films. The compound does not show photochemical reactions of trans-cis isomerisation, and the observed phenomenon of photoinduced optical anisotropy (POA) cannot be associated with photoinduced trans-cis transitions as it is usually considered in viscous dye solutions and polymer films. A change in an interaction energy for excited molecules and local recrystallization as possible reasons of the photoinduced molecular reorientation are discussed.