Franco Alfredo, García-Macedo Jorge A, Marino I G, Lottici P P
Departamento de Estado Sóldido, Instituto de Física, Universidad Nacional Autónoma de México, México, D.F.C.R 04510, Mexico.
J Nanosci Nanotechnol. 2008 Dec;8(12):6576-83.
Pump-probe photoinduced birefringence measurements were carried out in amorphous and in nanostructured sol-gel films with Disperse Red 1 (DR1) azochromophores embedded in a SiO2 matrix. X-ray diffraction (XRD) patterns determine the long-range nanostructure order of the films, exhibiting a lamellar nanostructure, with two different d-spacings, due to the presence during the sol-gel process of the Sodium Dodecyl Sulfate (SDS) or of the Cetyltrimethylammonium Bromide (CTAB) ionic surfactants. The photoinduced birefringence measurements were performed on fresh and on heat treated films as a function of the pumping time. The measurements give us information about the effect of the nanostructures on the azochromophores orientation dynamics. As a result, for the same azochromophores concentration, annealed nanostructured films exhibited the largest azochromophore mobilities but by the other side, amorphous films had the largest signal intensities. Besides, we established a phenomenological model for the analysis of the azochromophores orientation in the films as a function of the pumping time.
在嵌入二氧化硅基质中的含有分散红1（DR1）偶氮发色团的非晶态和纳米结构溶胶-凝胶薄膜中进行了泵浦-探测光致双折射测量。X射线衍射（XRD）图谱确定了薄膜的长程纳米结构有序性，由于在溶胶-凝胶过程中存在十二烷基硫酸钠（SDS）或十六烷基三甲基溴化铵（CTAB）离子表面活性剂，呈现出具有两种不同d间距的层状纳米结构。作为泵浦时间的函数，对新鲜薄膜和热处理薄膜进行了光致双折射测量。这些测量为我们提供了有关纳米结构对偶氮发色团取向动力学影响的信息。结果，对于相同的偶氮发色团浓度，退火后的纳米结构薄膜表现出最大的偶氮发色团迁移率，但另一方面，非晶态薄膜具有最大的信号强度。此外，我们建立了一个现象学模型，用于分析薄膜中偶氮发色团取向作为泵浦时间的函数。
