Photosensitivity of holographic recording media based on films of polymer compositions with cadmium sulfide nanoparticles

The effect of doping with CdS nanoparticles of recording medium films for the thermoplastic holographic recording process, which are based on photosemiconductors (oligomers and cooligomers of glycidylcarbazole) and a dielectric (a styrene copolymer with octyl methacrylate) containing a photoconductivity sensitizer, on their photosensitivity was studied. The enhancement of photosensitivity of films by doping with nanoparticles is associated with the appearance of an additional channel for transport of electrons generated from sensitizer molecules. A difference in informational properties between the oligomer and the polymer films was revealed.     

The oxidation of niobium and the structure of niobium oxides

Results are given for the oxidation kinetics of niobium in air at 500–1000 °C, together with x-ray data on the oxides; -Nb₂O₅ (orthorhombic) is formed up to 850 °C, and above this -Nb₂O₅, also orthorhombic but with lattice constants nearly twice as large. The physics of the oxidation is discussed.     

Evolution of the Electroluminescence Spectra and the Acoustic Emission of the Epitaxial Structures of GaAsP

The dependence of the spectral position of the electroluminescence bands of epitaxial light-emitting diode n ⁺–n–p structures (GaAs_0.15P_0.85) on the density of a direct heterojunction current at different successive instants of time — before an acoustic emission and after it — has been revealed. The shifts of the electroluminescence bands accompanied by acoustic emission can be divided into three types according to the density of the current: (1) short-term shifts due to relaxation of the defect structure of a sample — at relatively low currents, (2) the magnitude of the reverse shift being determined by the current density — at large currents, and (3) formation of an IR band (1.5–1.1 eV) with irreversible degradation changing in the red (1.75 eV) and green (2.19 eV) bands of the electroluminescence spectrum — at ultrahigh currents (100–200 A/cm²).     

Resonance properties of a dielectric cube in a rectangular waveguide

Institute of Radio Engineering, Kharkov. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 11, pp. 1404–1407, November, 1989.     

Thermal expansion of Ni3Al-Ni3Nb alloys

Temperature dependence of the thermal expansion coefficient () of Ni₃Al-Ni₃Nb alloys was studied. All alloys were found to have an abrupt decrease of in the 500 °–550 ° temperature range. The two-phase, 94 wt.% of Ni₃Nb alloy was shown to have the lowest thermal expansion coefficient.     

Photovoltaic Properties of Polymer Film Composites with a Tetranuclear Copper Complex Cu4L4(OCH3)4 (L− = N,N′-Dibenzyl-N″-Trichloroacetylphosphotriamide)

Theoretical and Experimental Chemistry - A study was carried out on the photovoltaic and photoconductive properties of film composites of a copolymer of styrene with nonyl methacrylate and...     

Holographic Recording Media Based on Poly‐N‐Epoxypropylcarbazole Films Doped with Organic Dyes

A comparative analysis of the recording media based on polyNepoxypropylcarbazole films doped with cationic, anionic, and intraionic organic dyes has been carried out for the purposes of holographic interferometry. It is shown that in the case of application of intraionic dyes recording media have satisfactory information characteristics. The use of anionic and cationic dyes does not give a positive result because of the absence of the photoconductivity effect in the anionic dyes and of the high electrical conductivity of the films on increase of the temperature of the cationic dyes. The effect of longterm storage of a latent image in the films with intraionic dyes makes it possible to use them for recording holograms with several exposures.     

The Effect of a Constant Electric Field on the Absorption Spectra of Polymethine Dyes

The intensities of the long wavelength absorption bands of symmetrical and unsymmetrical polycarbocyanines in polymer films are redistributed in a constant electric field. This redistribution depends in a regular manner on the chemical structure of the dyes. The spectroscopic effects are interpreted via a change in the probability of the vibronic transitions caused by redistribution of the electron density in the chromophore of the dye in the external electric field.     

Holographic recording media based on oligomers and co-oligomers with organic dye additives

We have created holographic recording media based on films of carbazolyl-, fluorenyl-, naphthyl-, and anthracenyl-containing oligomers and co-oligomers in which an intraionic organic dye is used as the sensitizer. We have established that the photoconductivity of the films and the photosensitivity of the recording media are higher in the case of co-oligomers with different donor moieties. We conclude that in the films of co-oligomers with different donor moieties in the “end” groups of the polymer chain, there is reduced probability of formation of excimers, which are centers for capturing photogenerated charge carriers, and therefore the photoconductivity of the film increases. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 132–135, January–February, 2007.