Advanced Materials Research Vol. 660

Abstract: A modified pulsed laser deposition (PLD) was employed to deposit GaAs nanocrystals on the surface of PMMA microspheres. This novel approach is distinguished by the fact that laser ablated materials are deposited uniformly onto the surface of spherical particles that are held constantly in a particle fludization unit. The XRD, SEM, EDX, TEM, EDP and PL results confirmed that cubic structured GaAs nanocrystals were deposited uniformly on the surface of PMMA microspheres with an average diameter of about 15 nm.

Abstract: As one kind of organic photochromic optical storage material, fulgides are well-known for their thermally irreversibility. The two-photon absorption 3D optical storage technology is one of the hot research topics in the field of high-density information storage. Using optical image storage technology the recording and reading rates can be improved. In this paper, it’s found that in one kind of 3-indoly-benzylfulgimide/PMMA film, there exits two-photon absorption property. And depending on this property, the two-photon absorption photochromic optical image storage was realized in an indoly-benzylfulgimide/PMMA film. It is proved that the N-benzyl-1,3,4-trimethyl-2-(2-methyl-) indoly-fulgimide has potential application in the two-photon absorption 3D optical storage.

Abstract: Thin film conducting polymer thiophene based that is poly(3,4-ethylenedioxythiophene): poly(styrene sulphonic acid) (PEDOT:PSS) blended with Polyaniline (PANi) have been prepared with different composition by using drop casting technique. The optical characterization has been done by analyzing the absorbance spectra in the wavelength 300 to 800 nm. The electronic parameters were calculated by using Tauc/Davis-Mott Model. The results obtained showed that the absorbance, optical energy and Urbach energy were dependence on the ratio of PEDOT: PSS to PANi compositions.

Abstract: Polarized absorption and dielectric spectra of blended poly (N-vinlycarbazole) (PVK) with polyvinylpyrrolidone (PVP) in different composition ratiosare investigated. Polymer coating was carried out using doctor blade technique on a quartz substrate. The polarized optical source was produced by using the uv-vis sheet polarizer. The polarized absorption and dielectric spectrum for parallel and perpendicular reveal that there are different significant results obtained between PVK and PVP with various polymer compositions.The polarized optical properties such aspolarization, ρwere calculated.These spectra indicate that the anisotropic properties of each polymer blends is different from each other.

Abstract: As one kind of organic photochromic optical storage material, fulgides are well-known for their thermally irreversibility. In this paper, two kinds of new fulgide materials, like pyrrylfulgide/PMMA film and 3-indoly-benzylfulgimide/PMMA film are used as storage materials. Different kinds of optical storage properties, like photosensitive spectral range, light sensitivity, resolution, fatigue resistance and thermal stability of them are measured. The experimental results show that for pyrrylfulgide and 3-indoly-benzylfulgimide, their photosensitive spectral range were 500nm~780nm and 480nm~720nm respectively; their maximum absorption were at 626nm and 573nm respectively; under 633nm light excitation, their light reaction constants of bleaching process on the exciting light polarization direction were 1.4×10-3cm2/mJ and 2.89×10-3cm2/mJ respectively; their resolution were both higher than 1680 lines/mm; they can be recycled more than 33 times and 70 times respectively; at room temperature they can be stored for 12 months and 14 months respectively. And it is concluded that pyrrylfulgide and 3-indoly-benzylfulgimide show better application potential in the field of rewriteable optical storage.

Abstract: The work is devoted to development of new cutting technology of semiconductor wafers on crystals by a method of laser controlled thermocracking. There are results of numerical and experimental researches of the cut sapphire wafers on crystals for light-emitting diodes by means of two lasers (СО2 laser and UV laser).

Abstract: The geometrical structures, electronic structures, and spectral properties of two Ir(III) complexes with tetraphenylimidodiphosphinate ligand were investigated theoretically. The ground and the lowest lying triplet excited states were fully optimized at the B3LYP/LANL2DZ. TDDFT/PCM calculations have been employed to predict the absorption and emission spectra starting from the ground and excited state geometries, respectively. The lowest lying absorptions were calculated to be at 436 and 405 nm for the two Ir(III) complexes, respectively, and they have the transition configuration of HOMO → LUMO. The lowest lying transitions can be assigned as metal/ligand-to-ligand charge transfer (MLCT/LLCT) character for the two Ir(III) complexes. Ionization potentials (IP) and electron affinities (EA) were calculated to evaluate the injection abilities of holes and electrons. The theoretical results can be expected to provide valuable information to design new OLED materials.

Abstract: To increase efficiency of continuous 1.5 μm laser radiation crystal laser media should be used instead of the glass ones. Generation efficiency in major laser crystals with ytterbium and erbium is at a disadvantage in relation to phosphate glasses. A cause of this phenomenon is a reverse energy transfer. Could be found crystals comparable in efficiency with Yb-Er phosphate glasses At present a number of investigations on the use of ions relaxators Се 3+ in crystals Ca2Al2Si07 with ytterbium and erbium have been carried out to solve the problem of the reverse energy transfer in crystals [1,2]. It has been determined [1-3] that high content of cerium is needed to depress the reverse energy transfer. But cerium and ytterbium are in different ends of a lanthanide series, so silicate crystals with more isomorphic capacity such as Yb,Er,Ce:CaGdSiO (CGCS) have been proposed [3]. A sufficient solubility of Се 3+ ions in these crystals gives fast excitation relaxation on a laser level and guards against the reverse energy transfer from Er3+ to donor ions. Furthermore, a number of crystal media on the base of borate crystals with a developed phonon spectrum have been proposed [4,5]. They lack the reverse energy transfer, fast multiphonon nonradiative relaxation shunts the 4I11/2 – 4I13/2 Er3+ transfer. New crystals on the base of anhydrous borates – calcium-yttrium oxyorthoborates - Ca4YO(BO3)3 (YCOB) with ytterbium appeared recently [6], which showed high efficiency of generation, as well as calcium-barium fluor-orthoborates YbEr:Ca BaFBO3 (CBFB), in which ytterbium ions formed centers of luminescence with excellent characteristics [6]. Unfortunately, erbium ions in YCOB are characterized by high three level parameter [6], therefore the efficiency of generation Er,Yb:YCOB is not high. It has been determined recently that erbium ions in crystals CBFB have outstanding spectroscopic parameters, besides, between ytterbium and erbium ions fast energy transfer of electronic excitation takes place [7]. Since the efficiency of a sensitized laser medium depends on joint characteristics of the Yb and Er centres and the efficiency of their interactions, then available data allow considering crystals CBFB as a considerably promising matrix for an effective 1.5 μm laser. In order to obtain the most promising laser crystals and to answer the question cited above, it should be made their comparative analysis on basic spectroscopic and generative parameters. One of the important parameters related directly to the efficiency of the laser medium is an energy density of the generation threshold. Given spectroscopic parameters of active centers in crystals, the generation threshold of the one-activated laser medium (in an idealized model without passive losses) with a tree-level or quasi-four-level scheme of generation is specified by properties of active centers and can be easily determined by a simple formula [8]. The results obtained by this method are often used for determination of limiting parameters of the three-level laser media, the ytterbium media, for instance, and their comparative analysis [8]. There are known calculations of sensitized media generation parameters, among them the ytterbium-erbium glasses with a tube pumping [9], which although can be used for a diode pumping, nonetheless they are too unwieldy for simple estimation and comparative analysis. Hence there is a demand for simple analytical expressions such as [8] to calculate the lower limit of generation of the sensitized two-activated laser media with a diode pumping. The work reports the growing of single crystals CBFB and YCOB doped with erbium and ytterbium with erbium, and single crystals Yb,Er,Ce:CGS as well. We have made a comparative analysis of an ytterbium-erbium media for 1.5 μm lasers with a diode pumping on the base of simple expressions for limiting generation thresholds of the idealized sensitized media with a three-level scheme of generation, obtained in the approximation of balance equations without considering nonlinear and cumulative processes.

Abstract: ion plasma sputtering, carbon diamond-like films, modification, metal nanoclusters, optical properties, plasmon resonance.