Distinctive features of time-resolved photoluminescence of porous silicon coated with a layer of diamondlike carbon

Time-resolved photoluminescence from porous silicon coated with a diamondlike carbon film is investigated. The intensity of the photoluminescence from the carbon film is obserd to increase after deposition, and there is an accompanying change in the intensity and a shortwavelength shift of the photoluminescence band of porous silicon that depends on the porosity of its original layers. These changes are explained by the formation of carbon nanoclusters on the surface of the silicon filaments. Zh. Tekh. Fiz. 68, 83–87 (April 1998)     

Fluorescence Properties of Thiacarbocyanine Dyes at Low Temperatures

Measurements were carried out for time-resolved fluorescence spectra of dye solutions containing thiacarbocyanine and its derivatives with ethylene and vinylene bridges in the polymethine chain. At low temperature, an additional band appears in the spectrum related to an intramolecular electronic transition. Analysis of the transition lifetimes and a quantum-chemical model indicated that this transition should be attributed to a short-lived asymmetrical component formed along with the symmetrical component upon relaxation of the excited state but not appearing at room temperature due to conformational transformations.     

Spectral Characteristics and Surface Morphology of Organic Polymer Films Containing Vanadium Pentoxide Nanoparticles

Films of nanosized composites of poly(N-epoxypropylcarbazole) (pEPC) and poly(3,6-di-Br-N-epoxypropylcarbazole) (pdBEPC) with vanadium pentoxide (V₂O₅) are produced for the first time ever. The electroconduction in dark and when illuminated, absorption spectra, steady-state photoluminescence spectra, and time-resolved photoluminescence spectra for the composite films are studied. The results are compared with relevant data for the pEPC, pdBEPC, and V₂O₅films. A conclusion about the formation of donor–acceptor complexes with incomplete charge transfer [pEPC⁺···V₂O ₅ ^- ] and [pdBEPC⁺···V₂O₅ ^-] is made. The surface morphology of the composites differs in the size of V₂O₅ fibers and polymer grains; the polymer inclusions in the composites are of different character. A surface morphology study reveals that the composite constituents—polymer base and V₂O₅ fibers—are nanosized.     

Nature and kinetics of the self-quenching of excited states of chromium(VI) oxyanions

Absorption and emission spectroscopy, utilizing theoretical group analysis, was used to investigate the nature of triplet states of chrornate and bichromate ions in aqueous solutions. The complex kinetics observed for the quenching of phosphorescence is explained by competition of emission and rapid exchange of energy between triplet sublevels. Quenching of phosphorescence is observed in concentrated chromate ion solutions. The dimer nature of the bichromate ion prevents intermolecular exchange of energy between ions in view of the existence of a more effective intraionic energy transfer.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 6, pp. 337–341, November–December, 1994.     

Luminescence of poly-N-epoxypropylcarbazole

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 53, No. 1, pp. 41–49, July, 1990.