- Wafer-level filling of microfabricated atomic vapor cells based on thin-film deposition and photolysis of cesium azide
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The thin-film deposition and photodecomposition of cesium azide are demonstrated and used to fill arrays of miniaturized atomic resonance cells with cesium and nitrogen buffer gas for chip-scale atomic-based instruments. Arrays of silicon cells are batch
- Liew, Li-Anne,Moreland, John,Gerginov, Vladislav
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- Photolytic spectroscopy of simple molecules. I. The production of 5 2D atoms from Cs2
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A two-photon technique is reported for the measurement of relative cross sections for the selective photolysis of simple molecules into particular product channels.In a demonstration of this method two independently tunable dye lasers were used to sequentially dissociate molecules of Cs2 for wavelengths in the visible range and then to excite the resulting products to Rydberg states which could be readily ionized for detection.With this system the spectra were determined for the selective photolysis of Cs2 into product atoms in the 5 2D3/2 and 5 2D5/2 states.Two relatively broad absorption bands were found, each of which led to the preferential population of a different fine structure components of the 5 2D products.Analysis of the photolysis spectra indicated that both dissociation and predissociation mechanisms were responsible and led to the identification of a new 1Σu and 3Σu state correlated with the 5 2D atomic states.
- Collins, C. B.,Anderson, J. A.,Popescu, D.,Popescu, Iovitzu
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- Direct evidence of n-type doping in organic light-emitting devices: N free Cs doping from CsN3
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Cesium azide (CsN3) is confirmed to be decomposed during thermal evaporation. Only Cs could be deposited on tris(8-hydroxyquinolinato)aluminum (Alq3) and n-type doping is easily achieved. Organic light-emitting devices with CsN3 show highly improved current density-luminance- voltage characteristics compared to the control device without CsN3. To understand the origin of the improvements, in situ x-ray and UV photoemission spectroscopy measurements were carried out and a remarkable reduction in electron injection barrier is verified with successive deposition of Al on CsN3 on Alq3. CsN3 has a potential as alternative to doping the electron transport layer by replacing the direct deposition of alkali metals.
- Lee, Jeihyun,Lee, Hyunbok,Jeon, Pyungeun,Jeong, Kwangho,Gun Kim, Tae,Won Kim, Jeong,Yi, Yeonjin
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- Photolytic spectroscopy of simple molecules. III. The selective photolysis of CsKr and Cs2Kr at visible wavelengths
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In this work a two-photon technique was used for the measurement of the relative cross sections for the selective photolysis of an equilibrium distribution of CsKr and Cs2Kr populations existing at 523 K in the presence of 0.132 amagat Kr.The cross sections for photolysis that selectively produced the lowest four excited states of Cs were obtained.Over the wavelength range 420 to 660 nm, the resulting dispersion curves showed one major feature which could be attributed to CsKr, the 6s? -> 5d? band dissociating to produce Cs(52D5/2).Various considerations indicated that the other structures observed in the spectrum belonged to the trimer Cs2Kr formed from Cs2 through the attraction of a Kr by polarization forces.The occurrence in the spectra of both CsKr and Cs2Kr of relatively broad photolysis bands leading to extremely selective distributions of product state populations was found to be fairly common.As in the previous work with Cs2 it was observed that adiabatic and hence, state-selective dissociation occurred if the photolysis was excited at a transition energy not too much in excess of the threshold for the process.An examination of the kinetics of the photolysis products gave rate coefficients for the mixing and quenching of the fine structure components of Cs(52D) of 7*10-12 and 3.7*10-13 cm3sec-1, respectively.At the densities used in this experiment these implied that useful populations of single states of Cs could be photolytically pumped with broadband radiation for periods of the order of tens of nanoseconds, while populations of energy levels could be pumped for more than an order of magnitude longer period of time.
- Collins, C. B.,Lee, F. W.,Golnabi, H.,Davanloo, F.,Vicharelli, P. A.,et al.
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- An experimental and theoretical study of electronic excitation and charge transfer processes in collisions between Cs(62S1/2) atoms and Na+(1S0) ions in the 0.30-4.00 keV energy range
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The collisional system Cs+Na+ with both species in their ground electronic state, has been studied using the crossed molecular beams technique and measuring the resulting fluorescent decay. Emissions from electronically excited Cs(62P3/2) and Cs(72P1/2,3/2) atoms have been detected as well as those from excited Na(32P1/2,3/2) and Na(42D3/2,5/2) produced by electron transfer. Cross-section values in the 0.30-4.00 keV energy range have been measured for the four different collision channels as well as the branching ratio between the resolved J-states for Cs(72P1/2,3/2). A qualitative interpretation for some of the measured emission cross-sections as a function of the collision energy has been performed using ab initio one-electron calculations done for the (CsNa)+ quasimolecule. Hemiquantal dynamical calculations have been carried out at selected collision energies including radial and angular non-adiabatic couplings, comparing the calculated cross-sections with the experimental data.
- De Andrés,Sabidó,Aricha,Albertí,Lucas,Gadea,Aguilar
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- Prototype dispenser photocathode: Demonstration and comparison to theory
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A method to significantly extend the operational lifetime of alkali-based photocathodes by diffusing cesium to the surface at moderate temperature is presented and shown to restore the quantum efficiency (QE) of cesiated tungsten. Experimental measurements of QE as a function of surface cesium coverage compare exceptionally well with a recent theoretical photoemission model, notably without the use of adjustable parameters. A prototype cesium dispenser cell is demonstrated and validates the concept upon which long-life dispenser photocathodes can be based.
- Moody,Jensen,Feldman,O'Shea,Montgomery
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- ESR Study of paramagnetic Nickel Species Obtained by Reduction and Oxidation of Bis(1,3,5-triphenylformazanato)nickel(II)
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Diamagnetic bis(1,3,5-triphenylformazanato)nickel(II) was reduced or oxidized by chemical and electrochemical methods.The paramagnetic Ni(I) and Ni(III) complexes thus obtained were studied by means of ESR spectroscopy.Ni(I) complexes formed by alkali metal reductions showed remarkable changes in their g values, depending on the kinds of alkali metal used.The change of g-values, which related to the ionic radii of the alkali metal ions, was well interpreted by the axial coordination effect due to the alkali metal ions.The electrochemical formation of the Ni(I) complex showed a solvent-dependency; the nickel(II) ion was reduced in DMF solution, but not in acetonitrile.The g-components were 2.030 for g// and 2.001.The relation between the two g-components gave a dx2-y2 ground state for the Ni(I) ion in the complex.Their anisotropy was very small.The Ni(II) ion oxidized by both chemical and electrochemical methods showed a dz2 ground state.The three g-components were 2.056, 2.039, and 2.000 in DMF, which are similar to those obtained from the other oxidation methods.
- Kawamura, Yoshiko,Yamauchi, Jun
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- Employing Polar Solvent Controlled Ionization in Precursors for Synthesis of High-Quality Inorganic Perovskite Nanocrystals at Room Temperature
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All inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (PeNCs) are synthesized by employing polar solvent controlled ionization (PCI) method in precursors. The new strategy can be easily carried out at room temperature and allow to employ smaller amount of weaker polarity and a broader range of low-boiling low-toxic solvents. The as prepared CsPbX3 PeNCs reveal tunable emission spectra from 380 to 700 nm and high quantum yields over 80% with narrow full width at half maximum (FWHM). Meanwhile, larger “effective Stokes shifts” of PeNCs in PCI method, which enlarges 200% more than other PeNCs in regular methods, are observed. Most interestingly, the PeNCs growth process is coupling with some typical crystals formations. The main morphologies of CsPbI3 PeNCs are hybrid of nanorods and nanoparticles. The primary morphologies of CsPbBrxI3- x and CsPbBr3 PeNCs are nanowires, which are supposed to have great potentials for applying in laser arrays and highly sensitive photodetector applications. Furthermore, such superior optical is endowed to fabricate white light emitting diodes, which has wide color gamut covering up to 120% of the National Television Systems Committee color standard.
- Fang, Fan,Chen, Wei,Li, Yang,Liu, Haochen,Mei, Ming,Zhang, Ruan,Hao, Junjie,Mikita, Marus,Cao, Wanqiang,Pan, Ruikun,Wang, Kai,Sun, Xiao Wei
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- Cs10Tl6SiO4, Cs10Tl 6GeO4, and Cs10Tl6SnO3 - First oxotetrelate thallides, double salts containing "hypoelectronic" [Tl6]6- clusters
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Cs10Tl6TtO4 (Tt = Si, Ge) and Cs 10Tl6SnO3 were synthesized by the reaction of appropriate starting materials at 623-673 K, followed by fast cooling or quenching to room temperature, in arc
- Saltykov, Vyacheslav,Nuss, Juergen,Jansen, Martin
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p. 1163 - 1168
(2011/09/13)
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- First isolated hypoelectronic [In6]6- cluster in insulating Cs22In6(SiO4)4
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Cs22In6(SiO4)4 was synthesized by the reaction of appropriate starting materials at 673 K, followed by slow cooling to room temperature, in arc-welded tantalum ampoules. According to single-crystal X-ray analysis, the compound crystallizes in a new structure type (P21/n(no. 14), a = 14.3533(4), b = 16.1712(4), c = 25.0135(7) A, β = 94.368(1), Z = 4), consisting of [In6]6- clusters with the shape of a distorted octahedron or more appropriately described as a condensate of three face sharing tetrahedra. The cluster is the first example of a hypoelectronic isolated [In6] 6- indium cluster. The oxosilicate indide can be regarded as a double salt , Cs6In6 on one hand and the oxosilicate Cs4SiO4 (× 4) on the other, which form the quaternary structure by inhomogeneous intergrowth of partial structures. The electronic structure of Cs22In6(SiO4) 4 was examined by DFT calculations and compared to the one of Rb 2In3, which exhibits linked In6 polyhedra. According to the DOS the title compound is a semiconductor with a band gap of 0.5 eV, which is in agreement with its observed insulating character. [In 6]6- is an isolated cluster bearing inert electron pairs at each vertex. In contrast, [In6]4- in Rb2In3 only exhibits inert pairs at the apical atoms. The four basal atoms are linked to neighboring clusters by covalent bonds forming a 2D network. These bonding scenarios are supported by the analysis of the projected density of states, the electron localization function and the partitioning of the electron density according to Bader. Copyright
- Saltykov, Vyacheslav,Nuss, Juergen,Wedig, Ulrich,Prasad, Dasari L. V. K.,Jansen, Martin
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p. 834 - 839
(2011/09/13)
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- Homoatomic Stella Quadrangula [Tl8]6 in Cs 18Tl8O6, Interplay of SpinOrbit Coupling, and JahnTeller Distortion
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Cs18Tl8O6 was synthesized reacting the binary compounds CsTl and Cs2O. According to single crystal X-ray analysis, the title compound crystallizes as a novel structure type in the cubic space group I23 and is diamagnetic. The electronic structure of the extended solid and of excised Cs6Tl8 clusters has been examined by relativistic density functional calculations including spin-orbit coupling. Cs18Tl8O6 comprises a clusteranion [Tl 8]6- in the shape of a tetrahedral star. An isoelectronic cluster was found previously in Cs8Tl8O, however, with the shape of a parallelepiped. Both clusteranions can be derived from a homocubane unit by displacive distortions. It has been shown by quantum mechanical analyses that the closed-shell electronic structure of the parallelepiped is the result of a Jahn-Teller distortion, while in contrast the tetrahedral star in Cs 18Tl8O6 would still exhibit an open-shell degenerate HOMO within a scalar relativistic approximation. Only if spin-orbit coupling is considered, a closed-shell electronic system is obtained in accordance with the diamagnetic behavior of Cs18Tl8O 6.
- Wedig, Ulrich,Saltykov, Vyacheslav,Nuss, Juergen,Jansen, Martin
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p. 12458 - 12463
(2010/10/02)
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- Electron microscopy, spectroscopy, and first-principles calculations of Cs2O
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Oxides of cesium play a key role in ameliorating the photoelectron emission of various opto-electronic devices. However, due to their extreme reactivity, their electronic and optical properties have hardly been touched upon. With the objective of better understanding the electronic and optical properties of Cs2O in relationship to its structure, an experimental and theoretical study of this compound was undertaken. First-principles density functional theory calculations were performed. The preferred structural motif for this compound was found to be anti-CdCl2. Here three Cs-O-Cs molecular layers are stacked together through relatively weak van-der-Waals forces. The energy bands were also calculated. The lowest transition at 1.45 eV, was found to be between the K point in the valence band to the Γ point in the conduction band. A direct transition at 2 eV was found in the center (Γ) of the Brillouin zone. X-ray powder diffraction, transmission electron microscopy and selected area electron diffraction were used to analyze the synthesized material. These measurements showed good agreement with the calculated structure of this compound. Absorption measurements at 4.2 K indicated two optical transitions with somewhat higher energy (indirect one at 1.65 and a direct transition at 2.2 eV, respectively). Photoluminescence measurements also showed similar transitions, suggesting that the lower indirect transition is enhanced by three nearby minima at 1.5 eV in the Brillouin zone.
- Gemming,Seifert,Muehle,Jansen,Albu-Yaron,Arad,Tenne
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p. 1190 - 1196
(2008/10/09)
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- Process for producing sulfonylimide compound
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A process for producing sulfonylimide compound is represented by the formula (I) MN(SO2Rf1) (SO2Rf2) industrially easily at a low cost in an efficient manner comprising reactions of at least one sulfonyl halogenides represented by the formula (II) RfSO2X with anhydrous ammonia or an ammonium salt in the presence of a fluorine compound represented by the formula (III) MF, in which X represents either F or Cl among halogen elements of VIIb group in the periodic table, and M represents any one of Li, Na, K and Cs among alkali metals of group Ia in the periodic table, Rf1 and Rf2, which may be the same or different, respectively represent any one of a straight chain or branched compound of a fluoroalkyl, perfluoroalkyl, fluoroallyl or fluoroalkenyl group having 1 to 12 carbon atoms, and Rf in the formula (II) represents the same group as Rf1 or Rf2 in the formula (I).
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- Synthesis of glycol ethers
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This application relates to a process for making glycol ethers, said process comprising reacting an olefin oxide with an alcohol over a catalyst comprising a crystalline metallosilicate which is basic in character, wherein the molar ratio of alcohol to olefin oxide employed is at least 2:1.
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- Catalytic composition and process for the oxychlorination of ethylene using such a composition
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Catalytic composition comprising copper chloride, magnesium chloride and caesium chloride deposited on an alumina, which may be used in particular for the oxychlorination of ethylene into 1,2-dichloroethane. In the processes for the oxychlorination of ethylene in oxygen in a fluid bed, this catalytic composition makes it possible to obtain an excellent yield of 1,2-dichloroethane without causing the deposition of soiling material on the surface of the bundle of tubes of the heat exchanger located in the reactor.
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- Cs5[Na{W4N10}]: The first framework nitridotungstate(VI)
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Cs5[Na{W4N10}] was prepared from a mixture of NaNH2, CsNH2 and tungsten powder (molar ratio 1:10:4) at 700°C in autoclaves. After the reaction is finished the nitride is embedded in an alkali metal matrix. Dark red crystals were isolated by washing out the alkali metal with liquid ammonia at room temperature. The structure of Cs5[Na{W4N10}] was solved by X-ray single crystal data: I41 (No. 80), Z = 4, a = 13.926(3) A, c = 8.723(3) A, Z(Fo2) ≥ 3σ(Fo2) = 1535, Z(Variables) = 63, R/Rw = 0.040/0.052. The compound is highly sensitive against moisture giving oxotungstates and ammonia. It contains a framework of tetrahedra ∞3[WNN3/21.5-]. Sodium shares four terminal nitrogen ligands. Including sodium a distorted, β-cristobalite type arrangement ∞3[Na{W4N10}5-] results. It contains caesium in all interstices formed by twelve nitrogen ligands in so-called Friauf polyhedra. Johann Ambrosius Barth 1996.
- Niewa,Jacobs
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p. 881 - 884
(2008/10/09)
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- Teranry Oxides containing Anionic Gold
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The preparation and crystal structure of the novel ternary oxides M3AuO (M=Cs, Rb, K) containting anionic gold is reported. Cs3AuO (a=7.830(1) A, c=7.060(1) A) crystallizes as an hexagonal, Rb3AuO (a=5.501(1) A), K3AuO (a=5.240(1) A) as a cubic anti perovskite. Concerning to the ionic description (M(1+))3Au(1-)O(2-) in Cs3AuO gold exists as an anion. In Rb3AuO and K3AuO the anionic character of gold decreases respectively. The analysis of bond length and molar volumes gives support to this view, as well as investigations of conductivity and magnetic properties do.
- Feldmann, Claus,Jansen, Martin
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- Synthesis of 4-methyl thiazole
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Isopropylidene methylamine is reacted with SO2 to form 4-methyl thiazole in the presence of a modified zeolite catalyst that has been ion-exchanged with an ammonium salt and porefilled with an alkali metal salt.
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- Process for preparing unsaturated carboxylic acid ester
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Disclosed is a process for preparing, α, β-unsaturated carboxylic acid ester from α-hydroxycarboxylic acid ester, a α-alkoxycarboxylic acid ester or β-alkoxycarboxylic acid ester as a starting material by a vapor-phase catalytic reaction in the presence of a crystalline aluminosilicate modified with an alkali metal and a platinum group element as a catalyst. According to the process, α, β-unsaturated carboxylic acid can be produced efficiently.
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- New catalyst composition and process for oxidation of ethylene to ethylene oxide
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This invention relates to a supported silver catalyst for the manufacture of ethylene oxide which contains a combination of (a) cesium and (b) at least one other alkali metal selected from the group consisting of lithium, sodium, potassium and rubidium, which combination comprises (a) and (b) in amounts in relation to the amount of silver therein sufficient to increase the efficiency of ethylene oxide manufacture to a value greater than the efficiencies obtainable under common conditions from respective catalysts which are the same as said catalyst except that instead of containing both (a) and (b), one contains the respective amount of (a), and the other contains the respective amount of (b). There is also described herein a process of making such catalyst and a process for producing ethylene oxide with such catalyst.
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- PRODUCTION OF HIGH PURITY CAESIUM.
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High-purity cesium is prepared by azide decomposition, a method first described by Suhrmann and Clusius in 1926. All the necessary details are given for the preparation of pure cesium azide from cesium carbonate, and for the proper control of the thermolysis to cesium in vacuo. Product purity is assessed using Guinier X-ray and atomic absorption spectroscopy. Cesium of purity 99. 998% was obtained, the contaminants being other alkali metals, further removable by distillation.
- Blatter,Schumacher
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p. 307 - 313
(2008/10/08)
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- Process for the production of alcohols
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Methanol is converted into alcohols containing at least two carbon atoms by reaction with hydrogen and/or carbon monoxide at elevated temperature and superatmospheric pressure in the presence, as catalyst, of (i) an oxide of Th and/or U and (ii) one or more alkali metals the latter being present in an amount of at least 1% by weight. Preferably the catalyst is free of hydrogenating metals. The methanol can be prepared by reaction of hydrogen and carbon monoxide in the presence of a methanol-forming catalyst.
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- REACTION OF HYDRATED ELECTRONS WITH ALKALI METAL CATIONS IN ALKALINE AQUEOUS SOLUTIONS
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Confirming experiments of Walker et al. and Hart et al., we show by flash photolysis and pulse radiolysis that the decay of hydrated electrons in aqueous alkaline solutions leads to an intermediate which by illumination with soft UV light (λ > 250 nm) rev
- Telser, Th.,Schindewolf, U.
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p. 5378 - 5382
(2007/10/02)
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- Collisional dissociation and chemical relaxation of alkali halide molecules: 2000-4200 K
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Shock-induced dissociation and the subsequent chemical relaxation processes of diatomic alkali halide molecules have been studied by time-resolved absorption spectrometry of alkali atoms, halide ions, and alkali halide molecules.The salts studied in detai
- Milstein, Richard,Berry, R. Stephen
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p. 6025 - 6037
(2007/10/02)
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- Study of the chemiluminescent reaction between alkali dimers and oxygen atoms
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The reaction of alkali dimers with oxygen atoms has been studied in a crossed beam experiment.Strong chemiluminescence of the reaction products was observed.It is shown that the luminescence was emitted by alkali from the reaction M2+O->MO+M* (M alkali atom).M* can be excited up to exoergicity of this reaction at least in the cases M=Cs and Na.For M=Cs, detailed rate constants for the excitation of the different excited states have been determined using both laser induced fluorescence and chemiluminescence.The rates decrease nearly exponentially as a function of the excitation energy.They partly follow the expectation of statistical theories.Absolute reaction cross sections have been determined for all of the reactions investigated.They agree partially with those predicted by the harpoon model.
- Figger, H.,Straubinger, R.,Walther, H.
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p. 179 - 185
(2007/10/02)
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- Production of unsaturated nitriles
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Catalysts containing iron, molybdenum, bismuth and nickel, cobalt, magnesium, zinc, cadmium, calcium or beryllium have been found to give especially large volumes of acrylonitrile or methacrylonitrile in a given time when manganese, antimony, thorium, zirconium, yttrium or mixtures thereof are incorporated into the catalyst.
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