نتایج جستجو برای: alkali metal
تعداد نتایج: 210259 فیلتر نتایج به سال:
A unique approach for obtaining bright and efficient saturated green phosphors for alternating-current thin-film electroluminescent ~ACTFEL! device applications is presented. The approach involves color-shifting blue SrS:Cu,F ACTFEL phosphors into the green region of the spectrum via the incorporation of alkali metal ions into the SrS lattice. Alkali metals are incorporated into SrS:Cu,F phosph...
We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M(1)); and 1 alkali, alkaline earth or 3d/4d transition metal atom (M(2)) plus two to five (BH(4))(-) groups, i.e., M(1)M(2)(BH(4))(2-5), using a number ...
Quantum Monte Carlo methods are used to investigate the binding of a positron to the alkali-metal hydrides, XH (X = Na and K). We obtain positron affinities for the NaH and KH molecules of 1.422(10) eV and 2.051(39) eV, respectively. These are considerably larger than the previous results of 1.035 eV and 1.273 eV obtained from multireference single- and double-excitation configuration interacti...
The Fermi-contact interaction that characterizes collisional spin exchange of a noble gas with an alkali-metal vapor also gives rise to NMR and EPR frequency shifts of the noble-gas nucleus and the alkali-metal atom, respectively. We have measured the enhancement factor κ0 that characterizes these shifts for Rb-129Xe to be 493±31, making use of the previously measured value of κ0 for Rb-3He. Th...
We present an implementation of a robust quantum random number generator based on the quantum fluctuations of the collective spin of an alkali-metal vapor. The achieved bit rate is limited by the spin relaxation rate of the alkali-metal atoms 1 /T2 to about 1 kbit/s. However, the same physical scheme, which is impervious to limitations posed by single-photon detectors used in current implementa...
Synthesis of a large number of simple and complex polymetaphosphate glasses of alkali metals with the general formulae (MXM1 -X)P03)fl and (MM_12PO3) has been described, where M and M' = Li,Na, K, Rb or Cs; M" = Be, Mg,Ca,Sr,Ba,Zn,Cd,Pb,CuorNi;andx = 1,,4or4.Thepreparations have been carried out by heating alkali dihydrogen phosphate, metal oxide (or carbonate) and diammonium hydrogen phosphate...
A series of heterometallic aluminium-alkali metal species [AlMMe2{2,6-(MeO)2C6H3O}2]n have been isolated for lithium, sodium and potassium. These compounds can be generated by the reaction of [AlMe2{2,6-(MeO)2C6H3O}]2 with the metallated phenol [M{2,6-(MeO)2C6H3O}]n or through the reaction of the mixture of AlMe3 and the appropriate alkali metal alkyl base with two equivalents of 2,6-dimethoxyp...
Because of contradictions in the literature, we reinvestigated the kinetics of the Birch reduction, i.e. the hydrogenation of benzene and its derivatives in metal ammonia solutions (MAS; containing solvated electrons e and metal cations M) with alcohols to yield the corresponding cyclohexa-1,4-dien compounds (e.g. 2Li+ 2CH3OH+C6H6)2CH3OLi+C6H8). The kinetics of this reaction are obscured since ...
The complexive abilities of 5,11,17-tddert-butyl-23 amino-25.26,27,28-tet3propoxy-calix[4]arere and5,1127-tri-amino-23 acelyktert-butylamide-25,26,27,28-tetrabutoxy-calixplarene towards alkali metalions Lit Nat, Kt RIC and Cs+ in methanol-chloroform mixture have been evaluated at 25 °C, using UVVis spectrophotometric techniques. The results showed that the hgands are capable to complex with all...
For a mixture of alkali-earth atomic gas in the long-lived excited state ^{3}P_{0} and the ground state ^{1}S_{0}, in addition to nuclear spin, another "orbital" index is introduced to distinguish these two internal states. In this Letter we propose a mechanism to induce Feshbach resonance between two atoms with different orbital and nuclear spin quantum numbers. Two essential ingredients are t...
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