Photostability of J -aggregates adsorbed on TiO 2 nanoparticles and AFM imaging of J -aggregates on a glass surface

Abstract. Spectral properties and photostability of the 5,5'-6,6'-tetrachloro-1,1'-dioctyl-3,3'-bis-(3-carboxypropyl)-benzimidacarbocyanine (Dye 1) J-aggregate was investigated in solution and upon adsorption on TiO 2 nano-particles. Dye 1 was found to photodegrade on the surface of TiO 2 . Additionally, the self-assembly of Dye 1 was studied on a glass surface by non-contact atomic force microscopy (NCAFM). The dye molecules form a well-defined fiber like structure that extends for tens of micrometers. The internal structure of the fibers was clearly resolved and showed a number of small tubes wrapped around each other to form a helical structure

Change in the micellar aggregation number or in the size distribution?: a dynamic fluorescence quenching study of aqueous cetyltrimethylammonium chloride

Aqueous solutions of cetyltrimethylammonium chloride were studied by means of dynamic fluorescence quenching measurements to get information on the micellar aggregation number and size polydispersity as a function of surfactant concentration. The global analysis of multiple decay curves provided estimates with improved accuracy and precision and indicated a reduced polydispersity upon increasing surfactant concentration. As the quenching rate slows with increasing surfactant concentration it is concluded that there is a micellar growth, but that this growth preferably increases the aggregation number for the smaller aggregates in the initially polydisperse solutions.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada