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generation [ 7 ]. Light strongly coupled to molecular transitions has also been reported to alter chemical reactions [ 8 ], [ 9 ]. An interesting plasmonic system where strong coupling has been observed and utilized are metal nanoparticle arrays. In these arrays, the localized plasmonic resonances of the nanoparticles hybridize with diffracted orders of the periodic structure, forming lattice modes called surface lattice resonances (SLRs) [ 10 ], [ 11 ], [ 12 ]. The SLR modes couple to the absorption line of emitters, for example organic dye molecules, and reach the strong

hybrid structures consisting of semiconductor quantum dots (QDs) and conjugated organic dye molecules at a single particle level serve as an important sources and tools for the development of various applications. QDs are particularly promising for photonic applications due to their size-dependent spectral tunability, high extinction coefficient, broad absorption tail, relatively narrow emission bands and exceptional photostability [ 1 ]. On the other hand the biggest advantages of an organic materials are their versatility, easy processing, high brightness and small

Zeitschrift für Physikalische Chemie, Bd. 184, S. 173-183 (1994) © by R. Oldenbourg Verlag, München 1994 - 0942-9352/94 $ 3.00 + 0.00 The Effect of Pressure on Fluorescence of Crystalline Flexible Dye Molecules* By Z. A. Dreger1, J. M. Lang and H. G. Drickamer School of Chemical Sciences, Department of Physics and Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA Dedicated to Prof. Dr. F. Hensel on the occasion of his 60th birthday (Received August 18, 1992) High pressure / Fluorescence / Photochemistry \ Visible spectroscopy / Solid

Abstract

The solid host of a laser dye modifies its spectroscopic properties with respect to its liquid host. During the Sol-Gel process the dye molecules suffer from changing their environment. Two parameters affect this matter, the change in the concentration due to the evaporation of the solvent (drying) and the caging of dye molecules inside the pores or attachment to the silica network. Rhodamine 6G absorption and fluorescence spectra with different concentrations, during Sol-Gel time processing, have been studied. Both, absorption and fluorescence spectra of the dye in the solid host, for different concentrations, show a blue-shift relative to its liquid phase.

Abstract

Layer charge is one of the key parameters used for the characterisation of expandable clay minerals, smectites. It determines most significant properties of the material which are important from the industrial application point of view. This work is related to a novel method introduced to characterize the layer charge of smectites, based on using cationic organic dyes as molecular sensors. One xanthene and four phenothiazine cationic dyes were tested using reduced charge montmorillonites (RCMs) and compared with methylene blue, which has been used most frequently. The characterization of the charge was based on the formation of molecular assemblies (H- and J-aggregates) composed by dye cations, which were easily detectable using absorption spectroscopy in the UV/VIS spectrum. More detailed characterization of the spectra required calculations of second-derivative curves. For all of the reaction systems tested in this work, the molecular aggregation increased with the layer charge of RCMs. Slight to moderate differences in the formation of dye assemblies related to the differences in the molecular structures of the individual dye cations. For example, the molecular asymmetry of azure A brought about the formation of coexistent species of similar structures. The structure of the heteroaromatic skeleton affected the extent of the aggregation and spectral changes with time. The presence of reactive, non-substituted amino groups in thionine cations probably partially decomposed in the clay mineral colloids based on high-charge RCMs. Any of the tested dyes could be used as molecular sensors for empirical characterization of the layer charge of clays taking into account the differences mentioned above.

G. Wahling Institut für Angewandte Physik der Universität Hamburg * Z. Naturforsch. 36a, 588-594 (1981); received April 30, 1981 Surface plasmons on silver films covered with organic monolayers (dye molecules (S 120) de­ posited on cadmium arachidate Scheibe or j aggregate) are studied in detail. The optical proper­ ties of this system derived from reflection measurements can be described by a rather simple one electron oscillator model. The damping of its eigenfrequency is rather small due to the regular arrangement of the dye molecules. ATR measurements

LICHTABSORPTION VON FARBSTOFF-MOLEKÜLPAAREN IN SAND WICHSYSTEMEN 1 8 2 1 Lichtabsorption von Farbstoff-Molekülpaaren in Sandwichsystemen aus monomolekularen Schichten V.CZIKKELY, G.DREIZLER, H . D . F Ö R S T E R L I N G , H . K U H N , J.SONDERMANN , P .TILLMANN und J . W I E G A N D Physikalisch-Chemisches Institut, Universität Marburg (Z. Naturforsch. 24 a, 1821—1830 [1969] ; eingegangen am 9. August 1969) The absorption spectra of cyanine-like dye molecules in monolayer assemblies are investigated. Pairs between two different dye molecules were

energy transfer between dye molecules and the number of detergent molecules in a micelle may be obtained. 1. Introduction It is well known that dye solutions change their characteristics when detergents are added. Deter- gent molecules above a critical concentration con- stitute micelles in aqueous solutions. These micelles are shaped differently depending on the kind of detergent and solvent. Spherical, ellipsoidal or lamellar micelles have been recognized [1—3J. The polar part of the detergent molecule is directed towards the water phase and the nonpolar

- perimental and quantum chemical calculations the orientation of the transition moments of the dye molecules is proposed. Introduction Recently, studies of the dependency of the spectral characteristics of methine dyes on the molecular composition of the dyes, on the solvent polarity and on the temperature of the sample were made [1—3]. The aim of this study was to find out the orienta- tion of absorption and fluorescence transition mo- ments and their thermal motion in solvents with different viscosities. The experimental results are compared with Pariser

@ehf.uni-oldenburg.de Z. Naturforsch. 64a, 518 – 530 (2009); received January 26, 2009 Dye-sensitized zinc oxide thin films were prepared, characterized and optimized for applications as photoelectrochemically active electrodes. Conditions were established under which crystalline thin films of ZnO with a porous texture were formed by electrochemically induced crystallization con- trolled by structure-directing agents (SDA). Dye molecules were adsorbed either directly as SDA during this preparation step or, preferably, following desorption of a SDA. The external quantum effi- ciency