- Ultrapurification of 76Ge-enriched GeH4 by distillation
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76Ge-enriched germane has been ultrapurified by low-temperature distillation. The nature and concentration of molecular impurities in the germane samples were determined by gas chromatography/mass spectrometry, high-resolution Fourier transform IR spectroscopy, and gas chromatography. The distillate contains no more than 10-5 mol % hydrocarbons, 10 -4 mol % carbon dioxide, 10-3 to 10-1 mol % digermane and trigermane, and -5 mol % other impurities. A distinctive feature of the impurity composition of the isotopically enriched germane samples is the presence of silicon tetrafluoride and sulfur hexafluoride impurities. Pleiades Publishing, Ltd., 2011.
- Adamchik,Bulanov,Sennikov,Churbanov,Sozin,Chernova,Kosheleva,Troshin
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- Effect of temperature on B(C6F5)3-catalysed reduction of germanium alkoxides by hydrosilanes - a new route to germanium nanoparticles
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Reduction of Ge(OBu)4with PhMe2SiH catalyzed by B(C6F5)3at ambient temperature leads to GeH4. We discovered that a higher temperature (above 100 °C) completely changes the reaction course by producing germanium nanoparticles (Ge NPs) in high yield. This process provides a simple one-pot method for Ge NPs synthesis from readily available substrates under mild conditions.
- Cypryk, Marek,Fortuniak, Witold,Mizerska, Urszula,Rubinsztajn, Slawomir,Uznanski, Pawel,Zakrzewska, Joanna
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- Laser CVD of nanodisperse Ge-Sn alloys obtained by dielectric breakdown of SnH4/GeH4 mixtures
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TEA CO2 laser-induced dielectric breakdown of an equi-molar mixture of gaseous stannane and germane in Ar allows decomposition of both metal hydrides and chemical vapour deposition of the nanostructured Ge/Sn films. Analysis of the films by FTI
- Krenek, Tomas,Bezdicka, Petr,Murafa, Nataliya,Subrt, Jan,Pola, Josef
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- Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
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Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)CNtBu, Ph2CCH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
- Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
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supporting information
(2019/04/17)
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- Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
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Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)C=NtBu, Ph2C=CH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
- Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
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supporting information
p. 6082 - 6091
(2019/04/17)
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- H2MBH2 and M(μ-H)2BH2 Molecules Isolated in Solid Argon: Interelement M-B and M-H-B Bonds (M = Ge, Sn)
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Laser-ablated boron atoms react with GeH4 molecules to form novel germylidene borane H2GeBH2, which undergoes a photochemical rearrangement to the germanium tetrahydroborate Ge(μ-H)2BH2 upon irradiation with light of λ = 405 nm. For comparison, the boron atom reactions with SnH4 only gave the tin tetrahydroborate Sn(μ-H)2BH2. Infrared matrix-isolation spectroscopy with deuterium substitution and the state-of-the-art quantum-chemical calculations are used to identify these species in solid argon. A planar structure of H2GeBH2 with an electron-deficient B-Ge bond with a partial multiple bond character (bond order = 1.5) is predicted by quantum-chemical calculations. In the case of M(μ-H)2BH2 (M = Ge, Sn) two 3c-2e B-H-M hydrogen bridged bonds are formed by donation of electrons from the B-H σ-bonds into empty p-orbitals of M.
- Zhao, Jie,Beckers, Helmut,Huang, Tengfei,Wang, Xuefeng,Riedel, Sebastian
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p. 2218 - 2227
(2018/02/23)
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- Molecular synthesis of high-performance near-ir photodetectors with independently tunable structural and optical properties based on Si-Ge-Sn
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This Article describes the development of an optimized chemistry-based synthesis method, supported by a purpose-built reactor technology, to produce the next generation of Ge1-x-ySixSny materials on conventional Si(100) and Ge(100) platforms at gas-source molecular epitaxy conditions. Technologically relevant alloy compositions (1-5% Sn, 4-20% Si) are grown at ultralow temperatures (330-290 C) using highly reactive tetragermane (Ge4H10), tetrasilane (Si4H10), and stannane (SnD4) hydride precursors, allowing the simultaneous increase of Si and Sn content (at a fixed Si/Sn ratio near 4) for the purpose of tuning the bandgap while maintaining lattice-matching to Ge. First principles thermochemistry studies were used to explain stability and reactivity differences between the Si/Ge hydride sources in terms of a complex interplay among the isomeric species, and provide guidance for optimizing process conditions. Collectively, this approach leads to unprecedented control over the substitutional incorporation of Sn into Si-Ge and yields materials with superior quality suitable for transitioning to the device arena. We demonstrate that both intrinsic and doped Ge1-x-ySixSny layers can now be routinely produced with defect-free microstructure and viable thickness, allowing the fabrication of high-performance photodetectors on Ge(100). Highlights of these new devices include precisely adjustable absorption edges between 0.87 and 1.03 eV, low ideality factors close to unity, and state-of-the-art dark current densities for Ge-based materials. Our unequivocal realization of the molecules to device concept implies that GeSiSn alloys represent technologically viable semiconductors that now merit inclusion in the class of ubiquitous Si, Ge, and SiGe group IV systems.
- Xu, Chi,Beeler, Richard T.,Grzybowski, Gordon J.,Chizmeshya, Andrew V.G.,Smith, David J.,Menendez, Jose,Kouvetakis, John
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p. 20756 - 20767
(2013/02/23)
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- Electrochemical preparation of germane
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Germane has been prepared through the electrochemical reduction of the germanate anion in alkaline solutions with a current efficiency of 40-45%. Active solution circulation in the cathodic zone and the use of an Sn or Cd cathode are shown to raise the germane yield. The current density and initial solution concentration have a weak effect on the reduction process.
- Turygin,Smirnov,Shalashova,Khudenko,Nikolashin,Fedorov,Tomilov
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p. 1081 - 1085
(2009/02/06)
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- Single vibronic level emission spectroscopic studies of the ground state energy levels and molecular structures of jet-cooled HGeBr, DGeBr, HGeI, and DGeI
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Single vibronic level dispersed fluorescence spectra of jet-cooled HGeBr, DGeBr, HGeI, and DGeI have been obtained by laser excitation of selected bands of the A1 A″-X 1 A′ electronic transition. The measured ground state vibrational intervals were assigned and fitted to anharmonicity expressions, which allowed the harmonic frequencies to be determined for both isotopomers. In some cases, lack of a suitable range of emission data necessitated that some of the anharmonicity constants and vibrational frequencies be estimated from those of HGeCl/DGeCl and the corresponding silylenes (HSiX). Harmonic force fields were obtained for both molecules, although only four of the six force constants could be determined. The ground state effective rotational constants and force field data were combined to calculate average (rz) and approximate equilibrium (rze) structures. For HGeBr rez(GeH) = 1.593(9) A, rez(GeBr)=2.325(21) A, and the bond angle was fixed at our CCSD(T)/aug-cc-pVTZ ab initio value of 93.6°. For HGeI we obtained rez(GeH) = 1.589(1) A, r ez(GeI)=2.525(5) A, and bond angle=93.2°. Franck-Condon simulations of the emission spectra using ab initio Cartesian displacement coordinates reproduce the observed intensity distributions satisfactorily. The trends in structural parameters in the halogermylenes and halosilylenes can be readily understood based on the electronegativity of the halogen substituent.
- Tackett, Brandon S.,Li, Yunjing,Clouthier, Dennis J.,Pacheco, Kezia L.,Schick, G. Alan,Judge, Richard H.
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- Infrared spectra of group 14 hydrides in solid hydrogen: Experimental observation of Pbh4, Pb2H2, and Pb2H4
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Laser-ablated Si, Ge, Sn, and Pb atoms have been co-deposited with pure hydrogen at 3.5 K to form the group 14 hydrides. The initial SiH2 product reacts completely to SiH4, whereas substantial proportions of GeH2, SnH
- Wang, Xuefeng,Andrews, Lester
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p. 6581 - 6587
(2007/10/03)
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- Infrared spectra of the novel Ge2H2 and Ge2H4 species and the reactive GeH1,2,3 intermediates in solid neon, deuterium and argon
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Laser-ablated Ge atoms and H2 molecules in excess neon and argon react during condensation to produce GeH1,2,3,4 as identified from infrared spectra with D2 and HD substitution, and from agreement with frequencies determined in recent gas-phase GeH and GeH2 fluorescence spectra and DFT calculations. The novel digermanium species Ge2H2 and Ge2H4 are formed in further reactions. Identification of Ge2H2 with the dibridged structure and Ge2H4 in the trans-bent C2h form is made possible by isotopic substitution and quantum chemical frequency calculations, which demonstrate the value of a close working relationship between experiment and theory. The photosensitive GeH3- anion is formed through electron capture by a GeH3 radical. All four germanium deuterides are observed in pure deuterium, which shows that further GeD and GeD2 reactions with D2 may require activation energy.
- Wang, Xuefeng,Andrews, Lester,Kushto, Gary P.
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p. 5809 - 5816
(2007/10/03)
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- The prototype Ge-H insertion reaction of germylene with germane. Absolute rate constants, temperature dependence, RRKM modeling and the potential energy surface
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Time-resolved studies of germylene, GeH2, generated by laser flash photolysis of 3,4-dimethyl-germacyclopentene-3, have been carried out to obtain rate constants for its bimolecular reaction with monogermane, GeH4. The reaction was studied in the gas phase over the pressure range 1-100 Torr, with SF6 as bath gas, at five temperatures in the range 292-520 K. The reaction of GeH2 with GeH4 to form digermane, Ge2H6, is pressure dependent, consistent with a third-body assisted association reaction. The high-pressure rate constants, obtained by extrapolation, gave the following Arrhenius equation: log(k∞/cm3 molecule-1 s-1) = (-11.17 ± 0.10) + (5.2 ± 0.7 kJ mol-1)/RT ln 10. These Arrhenius parameters are consistent with a moderately fast reaction occurring at approximately one-fifth of the collision rate. RRKM modeling, based on a variational transition state, used in combination with a weak collisional deactivation model, gave good fits to the pressure dependent curves, for a suitable choice of the critical energy, E(o), for reverse decomposition of Ge2H6. The step size (energy removed in a down collision) was chosen by analogy with the corresponding system for Si2H6 (collisional efficiency (β(c)) of ca. 0.7 for SF6). The value obtained for E(o) was 155 kJ mol-1. Corrected for thermal energy and combined with the insertion activation energy this gives ΔH°= 166 kJ mol- 1 for the decomposition of Ge2H6. There is no previous experimental determination of this quantity. From it we derive ΔH(f)°(GeH2) = 237 ± 12 kJ mol-1, in reasonable agreement with earlier estimates. From bond dissociation energy values the Divalent State Stabilization Energy (DSSE) of germylene (119 kJ mol-1) is larger than that of silylene (94 k J mol-1). Ab initio calculations at the correlated level reveal the presence of two weak complexes (local energy minima) on the potential energy surface corresponding to either direct or inverted geometry of the inserting germylene fragment. Surprisingly, the latter is the lower in energy, lying 25 kJ mol-1 below the unassociated reactants. These complexes rearrange to digermane with very low barriers. The implications of these findings and the nature of the insertion process are discussed.
- Beccera, Rosa,Boganov, Sergei E.,Egorov, Mikhail P.,Faustov, Valery I.,Nefedov, Oleg M.,Walsh, Robin
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p. 12657 - 12665
(2008/10/08)
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- Chemical Vapour Deposition of Germanium Films by Laser-induced Photolysis of Ethylgermanes
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Excimer laser photolysis of ethylgermanes EtnGeH4-n (n = 1-4) at 193 nm yields ethane, ethene and butane along with germanium deposited on the inner surface of the reactor.The distribution of gaseous products is remarkably different
- Pola, Josef,Parsons, Jonathan P.,Taylor, Roger
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p. 1637 - 1642
(2007/10/02)
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- Transition-metal Carbonyl Derivatives of the Germanes. Part 17. Tetracarbonylgermyl(trimethylgermyl)iron, , its Conversion into 2>, and hence to (characterised by X-Ray Crystallography) via
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The synthesis and spectroscopic characterisation of the mixed germane derivative (3) are described.This compound eliminates GeMe3H to give quantitatively 2> (4), which has a Fe2Ge2 four-membered ring.The GeH2 units of (4) react with , eliminating H2 and CO, to give (7).Quantitative loss of CO from (7) gives (8) which has been shown by an X-ray crystal structure determination to contain linked Co2Ge and Fe2Ge triangles.
- Anema, Skelte G.,Audett (nee Christie), Judy A.,Mackay, Kenneth M.,Nicholson, Brian K.
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p. 2629 - 2634
(2007/10/02)
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- EVOLUTION OF GERMANIUM HYDRIDE FROM ALKALINE SOLUTIONS BY ELECTROLYSIS.
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The authors determine the conditions corresponding to the optimal GeH//4 yield during electrolysis of the alkaline solutions. The results of this investigation show that germanium is evolved during electrolysis from alkaline solutions in the form of GeH//4 in a high mass yield. The presence of gallium ions in concentrations up to 34. 7 mu g/ml has no influence on conversion of germanium into hydride. The advantage of this method over chemical synthesis of GeH//4 lies in the simplicity of obtaining germanium hydride. One of its drawbacks lies in the considerable electrolysis time needed for complete extraction of germanium from the liquid phase.
- Khodyakov,Gromov
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p. 933 - 936
(2008/10/08)
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- The Preparation, Properties and Gas-Phase Molecular Structure of Difluoro(germylthio)phosphine
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Difluoro(germylthio)phosphine, PF2(SGeH3), has been prepared by the reaction of S(PF2)2 with GeH3Cl, and has been characterised by i.r., Raman, n.m.r. and mass spectroscopy.Cleavage reactions with Cl2 and HBr, donor reactions of the phosphorus atom and ex
- Ebsworth, E. A. V.,Macdonald, E. K.,Rankin, D. W. H.
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p. 221 - 234
(2007/10/02)
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