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Electronic structure methods based on density functional theory and coupled-cluster theory were employed to characterize elementary steps for the gas-phase thermal decomposition of bis(1,2,4-oxadiazole)bis(methylene) dinitrate (BODN). As typically found for nitrate ester-functionalized compounds, NO2 and HONO eliminations were the most energetically favorable unimolecular paths for the parent molecule's decomposition. From there, sequences of unimolecular reactions for daughters of the initiation steps were postulated and characterized. For intermediates found to have barriers to unimolecular decomposition that would make their rate at the temperatures and time scales of interest negligible, their decomposition via H-atom abstraction and radical-addition reactions was characterized. Creating a comprehensive network that can be employed to develop a detailed finite-rate chemical kinetics mechanism for simulating BODN's decomposition, the results provide a basis for modeling BODN's combustion, as well as its response to thermal loads germane to its aging, storage, and handling.

Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low economic and thermal budget were accomplished by the avoidance of ultra-high vacuum conditions or high temperature substrate pre-deposition bake for the process. Films were deposited with and without plasma assistance using germane (GeH4) precursor in a single step at process temperatures of 350–385 °C and chamber pressures of 1–10 Torr at various precursor flow rates. Film growth was realized at high ambient chamber pressures (&gt, 10−6 Torr) by utilizing a rigorous ex situ substrate cleaning process, closely controlling substrate loading times, chamber pumping and the dead-time prior to the initiation of film growth. Plasma allowed for higher film deposition rates at lower processing temperatures. An epitaxial growth was confirmed by X-Ray diffraction studies, while crystalline quality of the films was verified by X-ray rocking curve, Raman spectroscopy, transmission electron microscopy and infra-red spectroscopy.

The previously unknown silylgermylidyne radical (H3 SiGe; X2 A'') was prepared via the bimolecular gas phase reaction of ground state silylidyne radicals (SiH; X2 Π) with germane (GeH4 ; X1 A1 ) under single collision conditions in crossed molecular beams experiments. This reaction begins with the formation of a van der Waals complex followed by insertion of silylidyne into a germanium-hydrogen bond forming the germylsilyl radical (H3 GeSiH2 ). A hydrogen migration isomerizes this intermediate to the silylgermyl radical (H2 GeSiH3 ), which undergoes a hydrogen shift to an exotic, hydrogen-bridged germylidynesilane intermediate (H3 Si(μ-H)GeH); this species emits molecular hydrogen forming the silylgermylidyne radical (H3 SiGe). Our study offers a remarkable glance at the complex reaction dynamics and inherent isomerization processes of the silicon-germanium system, which are quite distinct from those of the isovalent hydrocarbon system (ethyl radical; C2 H5 ) eventually affording detailed insights into an exotic chemistry and intriguing chemical bonding of silicon-germanium species at the microscopic level exploiting crossed molecular beams.

The intra- and inter molecular inter-ring η 6 ⇌ η 6 -haptotropic rearrangements (IRHR), occurring by involving interactions to Ge atoms in arylgermanes, were investigated theoretically and experimentally. The new methods for the synthesis of non-symmetrical polyaromatic Ge compounds were elaborated. Digermane Ph 3 GeGeMe 2 Cl ( 2 ) was obtained from Ph 3 GeGeMe 2 NMe 2 ( 1 ) under action of Me 3 SiCl. Aryl digermane Ph 3 GeGeMe 2 (η 6 -C 6 H 5 )Cr(CO) 3 ( 4 ) was obtained after lithiation of (η 6 -C 6 H 6 )Cr(CO) 3 ( 3 ) with subsequent interaction with 2 . It was established that thermally induced intra molecular IRHR in 4 is not observed experimentally; at similar reaction conditions in the presence of tetralin C 10 H 12 ( 7 ) the bimolecular inter molecular IRHR occurs giving (η 6 -C 10 H 12 )Cr(CO) 3 ( 8 ). DFT analysis of the intra molecular IRHRs for model germane ( p -Tol) 2 Ge(H)(η 6 -Tol- p )Cr(CO) 3 ( MC1 ) and digermane Ph 3 GeGeH 2 (η 6 -Ph)Cr(CO) 3 ( MC2 ) indicates a plausible effect of 3c-2e (agostic) Ge–H···Cr interaction on success of such rearrangement. The theoretical activation barrier is determined to be in the range of 35–37 kcal/mol. The model compound (η 6 -C 6 H 3 (GeHPh 2 )Me 2 - p )Cr(CO) 3 ( 12 ) was obtained from (η 6 -C 6 H 4 Me 2 - p )Cr(CO) 3 ( 11 ). The decomposition of 12 was observed under conditions of thermally induced IRHR. Molecular structures of 8 , 11 and 12 in a crystal were investigated by XRD.

Polygermanes are germanium-based analogues of polyolefins and possess polymer backbones made up catenated Ge atoms. In the present contribution we report the preparation of a stable germanium polyethylene analogue – polydihydrogermane (i.e., (GeH2)n) – via two straightforward approaches that involve topotactic deintercalation of the CaGe Zintl phase. The resulting (GeH2)n possess morphologically dependent chemical and electronic properties and thermally decompose to yield amorphous hydrogenated Ge. We also show that the resulting (GeH2)n provide a platform from which functionalized polygermanes can be prepared via thermally-induced hydrogermylation-mediated pendant group substitution. This facile one-step derivatization reaction exploits Ge–H reactivity and opens the door to a wide array of tailored functional polygermanes.

Frustrated Lewis pairs (FLPs) based on nitrogen heterocycles (pyridine, pyrazole, and imidazole) with a silane or germane group in the α-position of a nitrogen atom have been considered as potential molecules to sequestrate carbon dioxide. Three stationary points have been characterized in the reaction profile: a pre-reactive complex, an adduct minimum, and the transition state connecting them. The effect of external (solvent) or internal (hydroxyl group) electric fields in the reaction profile has been considered. In both cases, it is possible to improve the kinetics and thermodynamics of the complexation of CO2 by the FLP and favor the formation of adducts., This work was carried out with the financial support from the Ministerio de Ciencia, Innovación y Universidades (PGC2018- 094644-B-C22) and Comunidad Autónoma de Madrid (P2018/EMT-4329 AIRTEC-CM). Thanks are also given to the CTI (CSIC) for their continued computational support

The methylgermylene species (HGeCH3 ; X1 A') has been synthesized via the bimolecular gas phase reaction of ground state methylidyne radicals (CH) with germane (GeH4 ) under single collision conditions in crossed molecular beams experiments. Augmented by electronic structure calculations, this elementary reaction was found to proceed through barrierless insertion of the methylidyne radical in one of the four germanium-hydrogen bonds on the doublet potential energy surface yielding the germylmethyl (CH2 GeH3 ; X2 A') collision complex. This insertion is followed by a hydrogen shift from germanium to carbon and unimolecular decomposition of the methylgermyl (GeH2 CH3 ; X2 A') intermediate by atomic hydrogen elimination leading to singlet methylgermylene (HGeCH3 ; X1 A'). Our investigation provides a glimpse at the largely unknown reaction dynamics and isomerization processes of the carbon-germanium system, which are quite distinct from those of the isovalent carbon system thus providing insights into the intriguing chemical bonding of organo germanium species on the most fundamental, microscopic level.

Significantly, global warming which is caused by CO2 emission and energy shortage are global problems resulting from artificial photosynthesis because it required many functions (light harvesting, Z water, and oxidation scheme). Therefore, photocatalytic systems development for CO2 reduction is germane in this field. Metal complexes molecular catalyst have become prevalent homogeneous catalysts for carbon dioxide (CO2) photocatalytic reduction since it was initially known as CO2 reduction catalysts in the 70s and the 80s, while utmost part involved macrocyclic cobalt(II) and nickel(II) complexes. This review article presents a broad understanding on some active catalysts recently reported as a metal complex molecular catalytic schemes for CO2 reduction, alongside catalytic activity, stability, selectivity under electro-reduction, and photoreduction circumstances. The progress of in situ spectroelectrochemical methods, typically supported via theoretical calculations, helped to access this know-how by providing information which enabled researchers to acquire more in-depth perception into unveiling the catalytic reaction and mechanisms intermediates.

Reactions of the trityl cations with germanes afford the germylium ions [R3Ge][B(C6F5)4] (1a: R = Et, 1b: R = Ph, 1c: R = nBu). These compounds react with germane or fluorogermane to give polynuclear species, which are sources of the mononuclear ions, The latter convert with phosphines to yield the [R3Ge-PR3]+ (4a: R = Et, 4b: R = Ph) cations. Catalytic dehydrofluorination reactions were observed for the C-F bond activation of fluoroalkanes when using germanes as hydrogen source.

Germanium (Ge) films have been grown on silicon (Si) substrate by ultrahigh-vacuum chemical vapor deposition with plasma enhancement (PE). Argon plasma was generated using high-power radiofrequency (50 W) to assist in germane decomposition at low temperature. The growth temperature was varied in the low range of 250°C to 450°C to make this growth process compatible with complementary metal–oxide–semiconductor technology. The material and optical properties of the grown Ge films were investigated. The material quality was determined by Raman and x-ray diffraction techniques, revealing growth of crystalline films in the temperature range of 350°C to 450°C. Photoluminescence spectra revealed improved optical quality at growth temperatures of 400°C and 450°C. Furthermore, material quality study using transmission electron microscopy revealed existence of defects in the Ge layer grown at 400°C. Based on the etch pit density, the average threading dislocation density in the Ge layer obtained at this growth temperature was measured to be 4.5 × 108 cm−2. This result was achieved without any material improvement steps such as use of graded buffer or thermal annealing. Comparison between PE and non-plasma-enhanced growth, in the same machine at otherwise the same growth conditions, indicated increased growth rate and improved material and optical qualities for PE growth.

In second language (L2) academic writing, being able to think in the L2 as opposed to thinking in the L1 and then translating into an L2 utterance may contribute to greater success in foreign-language writing. It reduces cognitive load, frees up more time and cognitive capacity to focus on syntactic structures in the target language and achieve synthesis of meaning using target-language vocabulary. The results reported here suggest that L2 learners may perform better in their writing if they avoid generating ideas in or calling upon resources from their native language (L1) to avoid splitting their attention, thus adding to working memory. These findings have implications for the relationship between cognitive load and L1 interference when writing in a second language.

Benzyltrialkylgermane cation radicals were generated and spectroscopically characterized by nanosecond transient absorption spectroscopy. The germane cation radicals were found to rapidly react with nucleophiles (e.g., alcohols) in reactions that were first-order in cation radical and first-order in nucleophile. The geometries of the transition states for nucleophilic substitutions on benzyl-silane and -germane cation radicals were investigated by using the endocyclic restriction test. Cation radicals containing tethered nucleophiles that required endocyclic transition states with small angles between the bond being formed to the nucleophilic atom and the bond to the leaving group reacted ∼250 times more slowly than cation radicals with tethered nucleophiles where a large bond angle can be accommodated. The results are consistent with the nucleophile-assisted fragmentations proceeding through an inversion transition state.

Charge density wave (CDW) is an important concept in condensed matter physics, germane to a number of physical phenomena. But the origin of CDW is still under debate, partly because the origin and properties of CDW are highly material-dependent. The concept of a CDW has been applied to many materials without a clear definition of the fundamental nature of CDW. As a result, misconceptions about CDW can be seen in the literature. In this review, we will try to describe and explain the possible existing misconceptions associated with the origin of CDWs.

International audience; Silicon-germanium nanostructures are promising anode materials for high stability, high capacity and fast cycling Li-ion batteries. In this work, we report on the outstanding performance of original SiGe/Si core@shell nanoparticle heterostructures synthetized in one step by laser pyrolysis of silane and germane. By tuning the silane to germane ratio, the composition of Si100-xGex alloy was readily adjusted. Nanoparticles with x = 0, 20, 47, 77, and 100 were investigated and the composition of each alloy (including internal mixed phases) was confirmed by X-ray diffraction and energy-dispersive X-ray spectroscopy. The electrochemical performances of the Si100-xGex alloys were evaluated by cycling half cell batteries from C/5 to 5C. The optimal trade-off between stability and capacity was obtained in Si53Ge47 core shell nanoparticles alloy. This material exhibits the best performance reported so far for SiGe compounds, with a reversible specific capacity of 1695 mAh.g-1 after 60 cycles (90 % of its initial value). The (de)alloying properties of this optimal Si53Ge47 heterostructure were followed by Operando synchrotron WAXS measurements, suggesting sequential lithiation of the various phases present in the material. The alloying process, combined with the realization of peculiar nanostructures composed of a Ge-rich core and a Si-rich shell, therefore allow to reach electrochemical properties suited for a practical application in energy storage device.

A cyclic (alkyl)(amino)germylene undergoes a ring expansion reaction with dibromomesitylborane (MesBBr2 ) to afford a six-membered dibromogermane derivative. In the presence of Lewis bases (PMe3 or Me NHC), reduction of the latter with two equivalents of potassium graphite (KC8 ) gives rise to cyclic (alkyl)(boryl)germylene-Lewis base adducts. Upon heating, the germylene-PMe3 adduct reacts with H2 to yield a germane, probably via a base-free germylene featuring a small HOMO-LUMO gap. Ministry of Education (MOE) Nanyang Technological University Accepted version We are grateful to Nanyang Technological University (NTU) and the Singapore Ministry of Education (MOE2017-T1-002-031) for financial support.

The activity of nitrogenase enzymes, which catalyze the conversion of atmospheric dinitrogen to bioavailable ammonia, is most commonly assayed by the reduction of acetylene gas to ethylene. Despite the practical importance of acetylene as a substrate, little is known concerning its binding or activation in the iron-rich active site. “Fischer–Tropsch” type coupling of non-native C(1) substrates to higher-order C(≥2) products is also known for nitrogenase, though potential metal–carbon multiply bonded intermediates remain underexplored. Here we report the activation of acetylene gas at a mononuclear tris(phosphino)-silyl-iron center, (SiP(3))Fe, to give Fe(I) and Fe(II) side-on adducts, including S = 1/2 Fe(I)(η(2)-HCCH); the latter is characterized by pulse EPR spectroscopy and DFT calculations. Reductive protonation reactions with these compounds converge at stable examples of unusual, formally iron(IV) and iron(V) carbyne complexes, as in diamagnetic (SiP(3))Fe≡CCH(3) and the paramagnetic cation S = 1/2 [(SiP(3))Fe≡CCH(3)](+). Both alkylcarbyne compounds possess short Fe–C triple bonds (approximately 1.7 Å) trans to the anchoring silane. Pulse EPR experiments, X-band ENDOR and HYSCORE, reveal delocalization of the iron-based spin onto the α-carbyne nucleus in carbon p-orbitals. Furthermore, isotropic coupling of the distal β-CH(3) protons with iron indicates hyperconjugation with the spin/hole character on the Fe≡CCH(3) unit. The electronic structures of (SiP(3))Fe≡CCH(3) and [(SiP(3))Fe≡CCH(3)](+) are discussed in comparison to previously characterized, but heterosubstituted, iron carbynes, as well as a hypothetical nitride species, (SiP(3))Fe≡N. Such comparisons are germane to the consideration of formally high-valent, multiply bonded Fe≡C and/or Fe≡N intermediates in synthetic or biological catalysis by iron.

Recently, the notion of topological phases of matter has been extended to higher-order incarnations, supporting gapless modes on even lower dimensional boundaries, such as corners and hinges. We here identify a collection of cubic spin-3/2 fermions with biquadratic touching of Kramers degenerate valence and conduction bands as a platform to strain-engineer higher-order topological (HOT) phases: external uniaxial strain gives birth to a HOT Dirac semimetal or an insulator, depending on its sign, featuring topological \emph{hinge} modes in the strain direction. The insulator in fact exhibits \emph{mixed} topology, and in addition supports edge modes on orthogonal planes. These outcomes are germane when the external strain is applied along one of the $C_{4v}$ or coordinate axes, as well as $C_{3v}$ or body-diagonal, directions. Our findings place HgTe, gray-Sn, 227 pyrochlore iridates and half-Heusler compounds at the frontier of strain-engineered electronic HOT phases., 6 Pages, 1 Figure (Supplemental Material as ancillary file): Published version

Bandgap energy profiling is applied in a variety of materials for photovoltaic technologies, such as chalcogenides, III–V materials and perovskites. Bandgap profiling of the absorber layer is used to fight the fundamental loss mechanisms imposed by the bandgap energy of the absorber for the maximum voltage and current that a photovoltaic device can generate. The bandgap profile can be affected by a number of profiling strategies, such as the difference between the maximum and minimum bandgap energy, the position of the minimum bandgap energy, the width over which this minimum bandgap energy occurs and the total absorber width. These parameters have a complex effect on output characteristics of a photovoltaic device. Varying multiple parameters at once further increases the complexity, limiting the effectiveness of rigorous physical opto-electrical modelling. In this work we therefore present an expedient semi-empirical approach for the optimal bandgap profiling of stoichiometric absorbers. Using PECVD processed amorphous silicon germanium as a model, we present a unique set of semi-empirical relations that simulate the V OC and J SC of solar cells as a function of the bandgap energy profile. For this model, the influence of deposition conditions such as the relative germane flow rate, the deposition power and substrate temperature on the opto-electrical properties of a-SiGe:H films is first characterized. Opting for the relative germane flow rate to control the bandgap profiling, the experimental results of a large number of solar cells with profiled a-SiGe:H absorber are presented, varying: 1. the absorber thickness, 2. the peak germane flow rate, so minimum bandgap energy, and 3. the introduction of a plateau at the minimum bandgap energy. Using this experimental data and optical simulations, the expedience and effectiveness of the semi-empirical approach is demonstrated.

The high resolution infrared spectra of GeH 4 in its natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm − 1 and analyzed in the region of 1400–2000 cm − 1 where the first bending overtone 2 ν 2 , 2 ν 4 and combinational ν 2 + ν 4 bands are located. Ro–vibrational line positions and energies of the 70 GeH 4 species were analysed for the first time and line positions and energies of the 72 GeH 4 and 74 GeH 4 species were improved considerably in comparison with the preceding studies. The numbers of 2316/2406/873/3007/2257 transitions with J max = 21/23/18/22/19 of the 2 ν 2 ( A 1 − and E − type sub–bands), 2 ν 4 ( A 1 − , E − and F 2 − type sub–bands) and ν 2 + ν 4 ( F 1 − and F 2 − type sub–bands) bands of the 70 GeH 4 , 72 GeH 4 , 73 GeH 4 , 74 GeH 4 , and 76 GeH 4 molecules were used in the joint weighted fit of experimentally assigned transitions with the Hamiltonian model which takes the resonance interactions between the seven, ( 0200 , A 1 ) , ( 0200 , E ) , ( 0101 , F 1 ) , ( 0101 , F 2 ) , ( 0002 , A 1 ) , ( 0002 , E ) and ( 0002 , F 2 ) , vibrational states into account. From our preceding studies 5563 hot band transitions were also taken into account. As the result of a joint fit, a set of 129 fitted parameters was obtained which reproduce the initial 16422 experimental (including “hot”) transitions of five isotopologues with the d rms = 3.26 × 10 − 4 cm − 1 . A line strength analysis of the 1697 experimentally recorded transitions of all species was made by the fit of their line shapes with the Hartmann-Tran profile and 13 effective dipole moment parameters were obtained from the weighted fit which reproduce the initial experimental line strengths with the d rms = 3.4 % . Self–broadening coefficients of 993 lines and self–shift coefficients of 674 lines were determined from the multi–spectrum analysis of these lines.

The impurity composition of 28SiH4, 29SiH4, and 30SiH4 silanes and 72GeH4, 73GeH4, 74GeH4, and 76GeH4 germanes isotopically enriched to above 99.9 at % has been studied by gas chromatography/mass spectrometry using capillary adsorption columns. Impurities have been identified by comparing their mass spectra with NIST data and information available in the literature, and by inferring their structure from fragment ions and retention times. We have identified 53 impurity substances in silanes and 42 in germanes: permanent gases; saturated, unsaturated, halogen-containing, and aromatic C1–C9 hydrocarbons; their homologues; alkyl derivatives of silane and germane; chlorogermane; siloxanes; fluorosiloxanes; sulfur compounds; and dioxane. The silicon- and germanium-containing impurities have been shown to be isotopically enriched, as the major component. The detection limits of the impurities are 5 × 10–8 to 3 × 10–5 vol %, comparing well with the best results in the literature.

Buffer-free GeSn and SiGeSn films have been deposited on Si via a cold-wall, ultra-high vacuum chemical vapor deposition reactor using in situ gas mixing of deuterated stannane, silane and germane. Material characterization of the films using x-ray diffraction and transmission electron microscopy shows crystalline growth with an array of misfit dislocation formed at the Si substrate interface. Energy dispersive x-ray maps attained from the samples show uniform incorporation of the elements. The Z-contrast map of the high-angle annular dark-field of the film cross section shows uniform incorporation along the growth as well. Optical characterization of the GeSn films through photoluminescence technique shows reduction in the bandgap edge of the materials.

Germane is a tetrahedral molecule found in trace abundance in giant gas planets like Jupiter and Saturn. We have recently provided a database of calculated lines of the stretching fundamental bands in the 2100 cm − 1 region that is of high interest for planetology ( https://vamdc.icb.cnrs.fr/PHP/GeH4.php ). It is now necessary to study many rovibrational levels, including the lowest ones, in order to access the hot bands and thus to improve the model of the spectral region of interest for Jupiter, especially in the framework of the ongoing Juno mission. We present here a complete analysis and modeling of line positions and intensities in the ν 2 / ν 4 bending dyad region near 900 cm − 1 for all five germane isotopologues in natural abundance. Thanks to the high symmetry of the molecule, we use the tensorial formalism and group theory methods developed in the Dijon group, that allows us to provide a set of effective Hamiltonian and dipole parameters. The present study also leads to a refined value of the Ge–H equilibrium bond length of 1.51714(25) A. Finally, new calculated germane lines were derived and injected in the GeCaSDa database.

A novel methodology for assessing evaporation (up to 48 h) through lipid-nanofilms in vitro was developed. The influence of lipid-mixture compositions on evaporation rates was studied. The evaporative fluxes and rheology of lipid-nanofilms were compared with those of human tear-lipid nanofilms in vitro.A sessile-drop technique with precise drop-volume control was adapted to measure evaporation rates at constant temperature of 36 °C and humidity of 75 %. Model lipid solutions were deposited on the surface of aqueous drops to create nanofilms of 10-100 nm. The measurements of dynamic surface pressure vs. nanofilm-thickness were performed under the same conditions. The lipid-mixtures compositions were chosen to mimic that of human tear lipids. Evaporation through lipid nanofilms decreased with film thickness and aging. Evaporation through 70-nm films was 2.5-3 time slower than through 10-nm-thick films. Nonpolar-lipid mixtures reduced evaporation by approximately 35 %. The optimized model-lipid mixtures containing polar phospholipids reduced evaporation by 70-75 %, matching the evaporation-reduction by human-lipid nanofilms in vitro. These model mixtures exhibited interfacial rheology similar to human tear lipids in vitro.This methodology substantiated that aged lipid-nanofilms significantly reduced evaporation in vitro. These findings contradict to the previous reports suggesting that model lipid and meibum films do not retard evaporation in vitro. Polar phospholipids enhance evaporative resistance close to the level observed for human tear-lipid films in vivo. We hypothesize that unique rheological properties of tear-lipid nanofilms are germane to the specific mono- and bi-layered structures formed by phospholipids at the lipid-air and lipid-aqueous interfaces.

In CEA-LETI, GeSn/SiGeSn stacks are typically grown at 100 Torr with Ge2H6, Si2H6 and SnCl4 and temperatures in the 301°C-363°C range. Ge2H6 has however a reputation of being unstable for high concentrations (10% in H2). The short shelf time can be adressed by switching over to lower concentrations and regularly changing bottles, which is complex as Ge2H6 is costly and complicated to order. One solution could be to switch from digermane to germane, which was shown by several R&D institutes to yield high quality GeSn layers. The epitaxy tools used, then, were capable of Atmospheric Pressure CVD (i. e. @ 760 Torr), while we have Reduced Pressure CVD chambers that can operate only up to a few hundreds of Torr. We have thus investigated the growth of tens of nm thick GeSn layers on 2.5 µm thick Ge Strain-Relaxed Buffers, themselves on Si(001). First GeSn growth trials at 349°C, 100 Torr with the same GeH4 flow than Ge2H6 did not yield any peaks in X-Ray Diffraction (XRD). Changing the Mass-Flow Controller and using a GeH4 flow 4 times higher resulted in modest Sn content layers, with some Sn surface segregation, however. Increasing, for fixed GeH4 and SnCl4 flows, the precursor partial pressures by (i) reducing the H2 carrier flow or (ii) increasing the chamber pressure resulted in linear GeSn Growth Rate (GR) and Sn content increases. Sn droplets were present on the surface up to 300 Torr, however. By contrast, GeSn layers grown at 400 Torr were high quality in XRD (well defined, intense peaks with thickness fringes, as shown in Fig. 1), with cross-hatched surfaces as the Ge SRBs underneath (Fig. 2). For a fixed GeH4 partial pressure (1.28 Torr), we have then evidenced a linear increase of the GeSn GR with the SnCl4 flow at 349°C. This increase was sub-linear at 325°C, with a slope change for P(SnCl4) = 0.008 Torr (Fig. 3). By contrast, the Sn content x was almost steady with the SnCl4 flow at 349°C. At 325°C, we had first of all an increase of the Sn content up to P(SnCl4) = 0.008 Torr, then a decrease, as shown in Fig. 4. Two SnCl4 partial pressures were therefore selected for the investigation of the impact of temperature on GeSn growth kinetics: 0.008 and 0.016 Torr (i.e. F(SnCl4)/F(H2) = 2E-05 or 4E-05). We had exponential increases, over the 301°C - 349°C range, of the GeSn GR with the temperature, with similar activation energies for both chemistries: 8.6 – 11.8 kcal mol.-1 for GeH4 ó 10.4 kcal. mol.-1 for Ge2H6 (Fig. 5). Meanwhile, the Sn content linearly decreased as the growth temperature increased, with a slope which was less for GeH4 than for Ge2H6 (- 1.0 or -1.1 % / 10°C, to be compared with - 1.7% / 10°C) (Fig. 6). Although the GeH4 flow was 4 times the Ge2H6 one and the chamber pressure 4 times higher (400 Torr ó 100 Torr), the GeSn GR was almost the same for a given SnCl4 flow. Sn contents were by contrast significantly lower with GeH4 than with Ge2H6. Halving, for the same GeH4 flow, the SnCl4 flow resulted in GeSn GR 40% lower but slighly higher Sn contents, which was once again counterintuitive! The Ge GR component (= (1-x)*GeSn GR) increased exponentially with the temperature, with similar values and activation energies for both precursors. Meanwhile, we had, over the 301°C-349°C range, a slight decrease of the Sn GR component (= x*GeSn GR) as the temperature increased. This was likely due to Sn sublimation. Sn GR components were 50% higher, for the same SnCl4 flow, with Ge2H6 than with GeH4. Complex interplays between precursors thus govern the GeSn growh kinetics with both precursors. Higher Sn contents and GeSn GR are nevertheless feasible with Ge2H6 + SnCl4 instead of GeH4 + SnCl4. Finally, while the GeSn GR and Sn contents were rather uniform over the 200mm wafer surface with Ge2H6 + SnCl4, the situation was definitely worse with GeH4 + SnCl4. GR were then significantly higher at the wafer edges than close to the center (although the Sn content was fairly uniform). Figure 1

Photochemical reactions of germane and diphenylgermane with Ru(PP) 2 H 2 (PP = R 2 PCH 2 CH 2 PR 2 or DuPhos, R = Ph dppe, R = Et depe, R = Me dmpe) are reported. Reaction with GeH 4 generates a mixture of cis and trans isomers of Ru(PP) 2 (GeH 3 )H except for the DuPhos complex which yields the product only in the cis form. In situ laser photolysis (355 nm) demonstrates that the initial product is the cis isomer that undergoes thermal isomerization to the trans isomer. The complex cis-[Ru(dppe) 2 (GeH 3 )H] crystallizes selectively, allowing determination of its X-ray structure as a germyl hydride with a long Ru-H···Ge separation of 2.64(3) Å indicating that no residual interaction between the RuH and Ge is present. DFT calculations are also consistent with full oxidative addition. The structure of cis-[Ru(DuPhos) 2 (GeH 3 )H] reveals significant distortion from an octahedral geometry. The major species in the crystal (95%) exhibits a structure with a Ru-H···Ge distance of 2.42(5) Å suggesting negligible interaction between these centers. DFT calculations of the structure are consistent with the experimental determination. The reactions of Ru(PP) 2 H 2 with diphenylgermane yield cis-[Ru(PP) 2 (GePh 2 H)H] exclusively for PP = dmpe and depe, while the cis isomer is dominant in the case of dppe. A photochemical competition reaction between Ru(dppe) 2 (H) 2 and the two substrates Ph 2 SiH 2 and Ph 2 GeH 2 results in both Si-H and Ge-H oxidative addition activation with a kinetic preference (0.18:1) for the germyl hydride product. Thermal conversion of Ru(dppe) 2 (SiPh 2 H)H to Ru(dppe) 2 (GePh 2 H)H is observed on heating.

A reply to the comments by Marx and Jayatilaka and coworkers on our publication on protonated methane/silane/germane is given in this article.

The SAGE experiment, which measures the flux of solar neutrinos, contains approximately 50 tonnes of liquid gallium metal. Low-energy neutrinos interact with the isotope Ga 71 in the Ga and convert it into Ge 71 at a rate of approximately one atom per day. In each measurement of the solar neutrinos about 210 μg of a stable Ge isotope in a Ga matrix is added to the Ga and the mixture is stirred to homogeneity. After a 30-day exposure of the gallium to solar neutrinos, any germanium is chemically extracted from the gallium. The Ge is converted into the gas germane and the number of Ge 71 atoms that it contains is measured in a proportional counter. After 6 months of counting, the Ge is removed from the counter, dissolved in an aqueous solution, and the isotopic content of Ge in this solution is measured by ICP-MS. The efficiency of extraction of Ge from the Ga is calculated from the measured mass and isotopic content of added and extracted Ge. In 75 recent exposures of the Ga to solar neutrinos the average Ge extraction efficiency was 97.7 ± 1.1%. This uncertainty in extraction efficiency is much less than the 3.3% uncertainty obtained by measurements of Ge mass alone, i.e., without isotopic analysis.

Auto-oxidation of polyethylene (PE) is of a common occurrence and could be triggered by several physical and chemical factors. In this study, for the first time, we report a comprehensive theoretical account on the initial oxidation of crystalline PE at low temperatures prior to its melting. We map out potential energy surfaces for large number of reactions, most notably, initial abstraction by O2 molecules, formation of peroxy- and hydroperoxyl adducts, unimolecular eliminations of HO2 and H2O as well as C C bond fissions. Rate constants have been estimated for all considered reactions over the temperature range of 300–800 K. We have discussed noticeable similarities between the oxidation of PE and that of gas-phase alkanes. Results presented herein provide new insights into the solid-state oxidation of PE and germane crystalline polyolefins/paraffins and pure carbon–hydrogen-type polymers.

The impurity composition of germane has been studied by gas chromatography/mass spectrometry. We have determined permanent gases, C1–C9 hydrocarbons, fluorine- and chlorine-containing and aromatic hydrocarbons, ethers, hydrogen sulfide, germane homologs, alkyl derivatives of germane, and chlorogermane. The content of some impurities in high-pure germane is 2 × 10–6 to 1 × 10–3 vol %. The detection limits for impurities lie in the range 4 × 10–8 to 5 × 10–5 vol %.

Amorphous germanium carbides have been prepared by X-ray activated Chemical Vapor Deposition from germane/allene systems. The allene percentage and irradiation time (total dose) were correlated to the composition, the structural features, and the optical coefficients of the films, as studied by IR and UV-VIS spectroscopic techniques. The materials composition is found to change depending on both the allene percentage in the mixture and the irradiation time. IR spectroscopy results indicate that the solids consist of randomly bound networks of carbon and germanium atoms with hydrogen atoms terminating all the dangling bonds. Moreover, the elemental analysis results, the absence of both unsaturated bonds and CH3 groups into the solids and the absence of allene autocondensation reactions products, indicate that polymerization reactions leading to mixed species, containing Ge-C bonds, are favored. Eopt values around 3.5 eV have been found in most of the cases, and are correlated with C sp3-bonding configuration. The B1/2 value, related to the order degree, has been found to be dependent on solid composition, atoms distribution in the material and hydrogenation degree of carbon atoms.

Determining Ge isotopic compositions of sulfides is important to understand the ore-forming processes. Single step anion-exchange chromatography was previously used to recover Ge from silicates and lignites. We apply this procedure to recover Ge from sulfides before determining Ge isotopic compositions by hydride generation (HG)-MC-ICP-MS. Germanium is quantitatively recovered by the proposed sample preparation method. There are no obvious isotope biases for Ge-bearing solutions containing significant amounts of Cu, Sn, and W. However, δ 74 Ge values show obvious shifts if the solutions contain high Zn, Pb, and Sb, which is possibly attributed to suppression of germane formation that fractionates Ge isotopes. The long-term reproducibility for Ge standard solution is about ± 0.18‰ for δ 74 Ge. Spex and Merck standard solutions yield mean δ 74 Ge values of − 0.70 ± 0.19‰ and − 0.36 ± 0.08‰, respectively. The calculated δ 74 Ge value (− 5.13‰) of sphalerite standard based on doping experiments is indistinguishable from those of sphalerite without doping (− 5.05‰ and − 5.01‰). Sulfides from the Jinding, Shanshulin, and Tianqiao Pb–Zn deposits in SW China have δ 74 Ge values of − 4.94‰ to + 2.07‰. The paragenetic sequence of sulfides from the Shanshulin and Tianqiao Pb–Zn deposits is pyrite, sphalerite and galena from early to late. Sulfides from the same ore show a trend of δ 74 Ge pyrite 74 Ge sphalerite 74 Ge galena , which may be controlled by the kinetic or Rayleigh fractionation.

The authors here combine polarized neutron scattering experimental work with computational minimization of proposed Hamiltonians in an effort to understand the low-temperature magnetic behavior in small applied magnetic fields for LaCo${O}_{3}$. They provide an exceptionally comprehensive study of the phase diagrams generated by various Hamiltonians germane to a situation in which magnetic ordering occurs at twin boundaries due to antiferromagnetic chains crossing the boundary at an angle different than 90\ifmmode^\circ\else\textdegree\fi{}.