The optical properties and energy transition process in nanocomposite of polyvinyl-pyrrolidone polymer and Mn-doped ZnS

This study has been carried out on the optical properties of polyvinyl-pyrrolidone (PVP), the energy transition process in nanocomposite of PVP capped ZnS:Mn nanocrystalline and the influence of the PVP concentration on the optical properties of the PVP capped ZnS:Mn nanocrystalline thin films synthesized by the wet chemical method. The microstructures of the samples were investigated by X-ray diffraction, the atomic absorption spectroscopy, and transmission electron microscopy. The results showed that the prepared samples belonged to the sphalerite structure with the average particle size of about 2–3 nm. The optical properties of samples are studied by measuring absorption, photoluminescence (PL) spectra and time-resolved PL spectra in the wavelength range from 200 to 700 nm at 300 K. From data of the absorption spectra, the absorption edge of PVP polymer was found about of 230 nm. The absorption edge of PVP capped ZnS:Mn nanoparticles shifted from 322 to 305 nm when the PVP concentration increases. The luminescence spectra of PVP showed a blue emission with peak maximum at 394 nm. The luminescence spectra of ZnS:Mn–PVP exhibits a blue emission with peak maximum at 437 nm and an orange–yellow emission of ion Mn²⁺ with peak maximum at 600 nm. While the PVP coating did not affect the microstructure of ZnS:Mn nanomaterial, the PL spectra of the PVP capped ZnS:Mn samples were found to be affected strongly by the PVP concentration.     

Soft multihadron production from partonic structure and fragmentation functions

We describe a two-chain model for soft multiparticle production in hadronic collisions. The model is formulated in a parton framework and is consistent with the dual topological scheme for the Pomeron. The sole inputs are valence quark structure functions in the colliding hadrons and parton fragmentation functions, both of which are known from “hard” processes. Our model, which contains no adjustable parameters, reproduces the shape, the energy dependence, and the normalization of inclusive spectra both in the central region and in the fragmentation region. The model provides a natural explanation for the ratio of πp topp cross sections.     

Electronic structure of lithium graphite

X-ray photoemission spectra of vacuum cleaved LiC₆, prepared from highly oriented pyrolytic graphite, provide a direct measure of the filling of the graphite π bands by electrons from Li. The resulting Fermi energy shift is in agreement with recent band structure calculations and indicates near unity charge transfer from Li. Core level spectra exhibit shifts compatible with the expected charge transger and line shapes showing strong asymmetries resulting from the metallic character of this compound.     

Multiparticle Effects in the Spectrum of Collective Excitations of Strongly Interacting Two-Dimensional Electron Systems (Brief Review)

JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been...     

Infra-red absorption bands 1-0, 2-0, 3-0 and 4-0 of the two isotopic species D79Br and D81Br of deuterium bromide

High resolution spectra of the 1-0, 2-0, 3-0, and 4-0 infra-red absorption bands of the two isotopic species of deuterium bromide have been recorded up to very high J values. The equilibrium molecular parameters obtained in the analysis fit the 267 observed lines within their experimental uncertainties, and give precise calculated wavenumbers for some observed chemical laser lines of these molecules.     

High resolution measurements of energy spectra of protons scattered from silicon crystals in the case of planar channelling

The energy spectrum of backscattered protons in the case of incidence along several planar directions shows a fine structure near the high-energy edge. This structure, an oscillatory dependence of the probability of backscattering vs. depth in the crystal, offers a possibility to study the proton trajectory in the lattice and also to obtain the stopping power of protons near planes in silicon.

Application of a simple model for the proton trajectory yields a stopping power near the planes 4 to 5 times higher than for random incidence. These effects have been observed using primary energies in the range 40–140 keV and for incidence along (110). (111), (100) and (112) planes.     

Solid Introduction to an ICP-Atomic Emission Spectrometer for the Analyses of Metals Contents of Air Filters

The direct introduction of solid samples (air filters) to the inductively coupled plasma source of an atomic emission spectrometer using a furnace atomizer has been studied. Conditions have been found for the analysis of elements which volatilize with varyling degrees of difficulty. Lead, copper and vandaium compounds retained on glass fibre filters from air pollution studies have been determined. The results are in good agreement with those obtained by means of established sample dissolution/atomic emision methods.     

Effect of gasketing and assembly design: a novel 10/3.5 mm multi-anvil assembly reaching perovskite pressures

A new design of multi-anvil assembly and modified gasket characteristics with octahedron and truncation edge lengths of 10 and 3.5 mm is presented for reaching pressures and temperatures over 24 GPa and 2000 °C, respectively. Partially dehydroxylated pyrophyllite half-gaskets with a tapered design fully nesting the octahedron have been employed to prevent excessive octahedron extrusion between the cubes. The assembly utilizes an axially placed thermocouple through the octahedral center, allowing two samples to be present at identical high P–T conditions on either side of the thermocouple during a run. A third sample can be used as a packing around the thermocouple, so long as that sample is inert with respect to the thermocouple and surrounding material. The temperature gradient within the sample locations has been well characterized using two-pyroxene thermometry in the CaO–MgO–SiO₂ system and numerical modeling calculations. The results indicate a good agreement in gradient shape, although the numerical model appears to under-estimate the magnitude of temperature change. The assembly maintains stable temperatures and provides low failure rates.