International Journal of ChemTech Research CODEN (USA): IJCRGG ISSN: 0974-4290 Vol.7, No.4, pp 1743-1750, 2014-2015 Investigation of PhotoinducedDichroism in Polymeric Poly(Methyl Methacrylate) Doped Sudan II Thin Films Adnan Deeb 1 and Yousef T. Salman* 2 1 Department of Chemistry, Faculty of Science, Damascus University, Syria 2 Department of Physics, Faculty of Science, Damascus University, Syria Abstract: Photoinduced dichroism in polymeric poly(methyl methacrylate) doped Sudan II thin films was investigated. Transmitted intensities in both parallel and perpendicular polarization state of the probe beam was recorded using pump- probe technique. Dichroism at different pump beam powers was calculated. Results showed that the transmitted probe beam intensity in the case of parallel polarization state is greater than that of the perpendicular polarization state. The dynamic behavior of the dichroism showed that it increases rapidly when the pump beam is switched on, saturates and then decreases when the pump beam switched off. The behavior of the dichroism as a function of the pump beam power showed that it increases, reaching a maximum and then decreases with increasing of the pump beam power. Keywords :Dichroism, Sudan II, Photoinduced. Introduction and Experimental Photoinducedtrans-cis isomerization, molecular reorientation and non-linear optical properties of azobenzene containing systems make them suitable for many opticalapplications 1 . Azobenzene and their derivatives have been extensively studied in the area of nonlinear optical properties, including second-order phenomena such as photoinduced poling andfrequency doublingand in third-order phenomena such as degenerate four-wave mixing and photorefractivity 2 . A number of groups have reported on the possibility of azobenzene materials in the areas of photonics and nanotechnology 3-5 . The importance of organic and polymeric nonlinear optical (NLO) materials for applications in nonlinear optics is widely recognized 6 . In this regard, and because of their potential utility for optical data storage, azo-chromophore containing polymeric films have attracted much attention. There is considerable interest in initiating and controlling changes in chromophore/ polymer compound properties by the use of photoinduced molecular rearrangements of the chromophore molecules which are incorporated in a guest –host system 2 . The phenomenon of anisotropic absorption of light or dichroism was discovered and named by Abbe Hauy, and was described subsequently in greater detail by Brewster 7 .Dichroism is a measure of the orientation of the nonlinear optical chromophore molecules in the host polymer 8 .The phenomenon was soon realized to be related to a combination of the intrinsic dichroism of chromophore molecules and the state of orientation existing in the polymer which leads to oriented absorption of chromophore molecules 7 .An equally important application of linear dichroism (LD) is the determination of sample or molecular structures. To a large extent, the sample structure determines the result of a LD experiment; and this is what makes it possible to extract structural information from a LD experiment 9 .The optical nonlinearities (NLO) of polymer films, that contain azo-compound, have been studied extensively 10- 15 .To the best of our knowledge, linear dichroism of poly(methyl methacrylate), PMMA, thin films using Sudan II chromophore has never been studied before. In this work, the dichroic behavior of Sudan II/ PMMAthin films chromophore was investigated. The relationship between the chromophore chemical structure and dichroism was examined. Guest-host polymeric samples were prepared from PMMA (MW: 36000) from Acros Organics, and Sudan II (95% chromophore content), from Aldrich. 4gr of PMMA was dissolved in 40ml of tetrahydrofurane