β- In 2 S 3 and β-In2−xAlxS3 thin films have been deposited on different substrates using the spray pyrolysis technique at 320 °C. X-ray diffraction, atomic force microscopy, and scanning electron microscopy were used to characterize the structure of the films; the surface compositions of the films were studied by Auger electrons spectroscopy and energy dispersive spectrometry (EDS), the work function and the photovoltage by the Kelvin method. Using these techniques, we have specified the effect of the nature of the substrate, of its surface morphology, of the introduction of small amounts of Al in the layer, on the properties of the films. The best crystallized of β-In2S3 were obtained for deposits on pyrex. This was improved by the introduction of Al atoms. The work function differences (φmaterial–φprobe) for β-In2S3 and β-In2−xAlxS3 deposited on steel were equal to −150 meV and to −180 meV, respectively. Putting Al atoms in the film increases φm (by about 30 meV) and induces the formation of a negative surface barrier. The concentration of In, S, and O elements increased when the samples were annealed under a vacuum, whereas the concentration of carbon decreased. The best composition was obtained for In2S3 deposited on SnO2 and annealed. The introduction of Al increases O and C concentrations and reduce In, Cl, and S concentrations. Analysis of the film compositions by EDS gives the following concentrations [In]=37%, [S]=52%, and [Cl]=11%.
High magnetic fields were used for the alignment of J-aggregates of cyanine dyes in solution leading to strongly polarized optical properties, yielding a maximum dichroic ratio of 13. The aligned aggregates were fixed by gelation resulting in samples that are stable at room temperature and exhibit strongly polarized absorption and emission spectra.
ZnO thin films have been grown on glass substrates using the spray pyrolysis technique. The depositions were carried out in the range of substrate temperatures from 400 to 500 °C. Highly c‐axis oriented ZnO films, having a strong (002) X‐ray diffraction line, are obtained at lower temperatures (400 to 420 °C). Film surfaces were analysed by contact Atomic Force Microscopy (AFM). On the other hand, we have used scanning microscopy performed at a frequency of 570 MHz to reach a microechography and acoustic signature V(z) of our samples in order to understand their qualities.
A bromide-modified silver (111) surface, covered by Jelly-type aggregates of a cyanine dye, is investigated by scanning tunneling microscopy (STM) in air. We show that, under appropriate conditions, light is emitted out of the junction by inelastic electron tunneling. Study of the relation between the light intensity and the tunnel bias clearly reveals a molecular influence on the light emission. Furthermore, through a spectral analysis, we show that sharp resonances appear for dye-covered surfaces by coupling of tip-induced plasmons with molecular excitations. This demonstrates that through STM-induced luminescence local spectroscopic information can be obtained on molecules.
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