Déformation photoinduite dans les films minces contenant des ...

Chapter 1pastel-00527388, version 1 - 19 Oct 2010The azobenzene molecules:photochromic materials andphotodeformation effects1.1 IntroductionAlthough the photochromic properties of the azobenzene molecules have been knownfor almost a century [1] nowadays the spectacular effects induced by their isomerizationstill draw great attention [2–16]. In particular, the photomechanical effects obtainedunder polarized light are among the most studied and widely debated, since the firstobservation of matter transport phenomena over a long range (hundreds of nm), in 1995[17, 18].In this chapter, after a brief description of the azobenzene molecules, we present someof the most remarkable results reported in the literature concerning the photoinduceddeformation phenomena observed in the far and in the near field. In particular, we focuson the open problems and the most debated interpretations.1.2 The azobenzene molecules1.2.1 The isomerizationThe structure of the azobenzene molecule consists in two phenyl rings connected by anazo group -N=N-, as is depicted in Figure 1.1. The molecule exists in two isomericconfigurations, the more stable trans (E) isomer and the metastable cis (Z) isomer, the7