Results 1 - 10 of 1182
Results 1 - 10 of 1182. Search took: 0.031 seconds
|Sort by: date | relevance|
[en] We have conducted Combined Array for Research in Millimeter-wave Astronomy observations of LiH, in absorption, toward three quasars. These quasars, B0218+357, PKS1830-211, and PKS0201+113, have redshifts of z = 0.685 - 3.387, and shift the LiH J = 1-0 transition to the 1 mm and 3 mm wavelength bands, where atmospheric absorption is sharply reduced from that predominating near the rest frequency of 443 GHz. We report a 3σ detection of LiH toward B0218+357 with a column density of 1.4 x 1012 cm-2 and place an upper limit on the 6Li/7Li ratio of <0.16. LiH was not detected toward any other source.
[en] Highlights: • STEM-EELS has been successfully applied to map Li in ion-irradiated γ-LiAlO2 pellets. • Direct evidence is found for preferred pathways of Li diffusion along the grain boundaries. • Isolated voids are identified as possible Li trapping sites in pellets during irradiation. • Possible lithium hydrides and/or hydrates are formed on the irradiated pellet surface. • Possible H-bearing molecules or particles are precipitated along the grain boundaries.
[en] Ru/C-catalyzed hydrogenation of m-xylylene diamine into 1,3-cyclohexanebis(methylamine) was greatly accelerated by the presence of LiNO3, NaNO2, or NaNO3. It was found that the effect of the nitrate salt was significantly affected by the size of cation. The promoting effect of the nitrate salt increased with the decrease of the cation size: LiNO3 ∼ NaNO3 > KNO3 > CsNO3 >> [1-butyl-3-methylimidazolium]NO3. XRD analysis of the recovered catalysts after the hydrogenation reactions showed that LiNO3 and NaNO3 were completely transformed into LiOH and NaOH, respectively, along with the evolution of NH3, while KNO3 and CsNO3 remained unchanged
[en] Highlights: • The electric properties of spatially confined LiH molecule are studied. • The effect of orbital compression is modeled by the helium atoms probes. • Spatial restriction causes a diverse changes in electrical response of LiH. • The anisotropic nature of exchange-repulsion energy has been disclosed. - Abstract: In this study the influence of directional character of the orbital compression on the exchange-repulsion energy as well as linear and nonlinear electric properties of lithium hydride was analyzed. In order to elucidate the effect of orbital compression anisotropy on the properties in question the supermolecular approximation has been employed. Within this approach various number of helium atom probes, at different orientations and distances from the LiH molecule, have been used to represent the chemical confining environment. The results of highly accurate ab initio calculations indicate that the investigated quantities strongly depend on the topology of confining environment.
[en] Studies of lithium hydride (LiH) reactions with H2O are reviewed in this paper. We discuss reaction products that are formed and the reaction kinetics involved. For discussion purposes, the studies are roughly categorized as reactions between LiH and H2O in low and higher concentration regimes, as well as reactions between LiH hydrolysis products. Both LiH and H2O can exist in many structural or phase variations and can contain various impurities, all of which may affect products and kinetics
[en] This brief review is devoted to the new field of exciton spectroscopy of isotopic crystals. The availability of many stable isotopes and well-developed techniques of their separation permits the growing of crystals of diamond, lithium hydride, zinc oxide, cuprous oxide, cadmium germanium, and silicon sulfides with controlled chemical composition. It is shown experimentally that the substitution of a heavy isotope for a light isotope results in an increase in the energy of the interband transitions with a nonlinear dependence on the isotope concentration, although the lattice constant of mixed isotopic crystals obeys, as a rule, Vegard's law. A comparative study of the temperature and isotope shifts of the fundamental absorption edge gives information on the main, but not the only, contribution to the shift of the zero-point vibrations. The substitution of a heavy isotope for a light isotope results in a nonlinear increase in the binding energy of the Wannier-Mott exciton and in an increase in the energy ΔLT of longitudinal-transverse splitting; the theoretical treatment of these effects presents a considerable challenge. In addition to the isotope shift, all the lines in exciton reflection (absorption) and luminescnece spectra exhibit an additional broadening. A comparison between experimental data and theoretical calculations of the concentration dependence of broadening of free exciton levels suggests that the broadening is mainly determined by the electron potential fluctuations caused by the isotope disorder of a crystal lattice. The electron potential fluctuations are assumed to be mainly determined by the nonlinear concentration dependence of the Froehlich exciton-phonon interaction. 152 refs., 18 figs., 2 tabs
[en] Electron-impact cross sections for the transitions between the vibrational levels of X 1Σ+ and A 1Σ+ electronic states of the LiH molecule, are calculated from threshold to 1000 eV by using the threshold-modified Massey–Mott approximation. The rate coefficients for the same transitions are also calculated in the range 0.1–1000 eV. Scaling relationships for both the v − v′ cross section and v − v′ rate coefficients are derived, allowing us to represent the calculated quantities in a compact analytic form. (paper)
[en] The applicability of Stieltjes-imaging techniques to calculations of molecular photodissociation cross sections is explored. Detailed comparisons for the diatomic molecules LiH and H2 are made which suggest that reasonable accuracy can be obtained with moderate basis sets. The methods are used to predict the photodissociation cross sections for absorption from low-lying vibrational levels of H3+