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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

The tropospheric gas composition of Jupiter's north equatorial belt (NH3, PH3, CH3D, GeH4, H2O) and the Jovian D/H isotropic ratio

The gas composition of the troposphere of Jupiter in the clearest regions of the North Equatorial Belt (NEB) was derived from the Voyager 1 IRIS data. The infrared spectrum for this homogeneous cloud free region was modeled to infer altitude profiles for NH3, PH3, GeH4 and H2O. The Profiles for NH3 and PH3 were found to be depleted in the upper troposphere but otherwise in agreement with their solar values at the 1 bar level. The mole fraction for CH3D was determined to be 3.5(+1.0 or -1.3) x 10 to the minus 7th power. The GeH4 mole fraction of 7+ or -2 x 10 to the minus 10th power at the 2 to 3 bar level is a factor of 10 lower than the solar value. The H2O mole fraction is approximately 1 x 0.00001 at the 2.5 bar level and is increasing to approximately 3 x 0.00001 at 4 bars where it is a factor of 30 lower than solar. Using IRIS infrared values for the mole fractions of CH3D and CH4 a value of D/H = 3.6(+1.0 or -1.4)x 0.00001 is derived. Assuming this Jovian D/H ratio is representative of the protosolar nebula, and correcting for chemical galactic evolution, yields a value of 5.5 - 9.0 x 0.00001 for the primordial D/H ratio and an upper limit of 1.8 to 2.4 x 10 to the minus 31st power cu cm for the present day baryon density.

Kunde, V.↗
DOE OSTI2020

Materials Data on GeH4 by Materials Project

GeH4 is alpha carbon monoxide-like structured and crystallizes in the orthorhombic Cmcm space group. The structure is zero-dimensional and consists of four germanium molecules and eight hydrogen molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeH4 by Materials Project

GeH4 crystallizes in the orthorhombic Cmmm space group. The structure is two-dimensional and consists of two hydrogen molecules and one GeH2 sheet oriented in the (0, 0, 1) direction. In the GeH2 sheet, Ge2+ is bonded in a square co-planar geometry to four equivalent H+0.50- atoms. All Ge–H bond lengths are 1.79 Å. H+0.50- is bonded in a linear geometry to two equivalent Ge2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeH4 by Materials Project

GeH4 is Silicon tetrafluoride-like structured and crystallizes in the monoclinic P2/c space group. The structure is zero-dimensional and consists of four germane molecules. Ge2+ is bonded in a tetrahedral geometry to four H+0.50- atoms. There is two shorter (1.53 Å) and two longer (1.54 Å) Ge–H bond length. There are four inequivalent H+0.50- sites. In the first H+0.50- site, H+0.50- is bonded in a single-bond geometry to one Ge2+ atom. In the second H+0.50- site, H+0.50- is bonded in a single-bond geometry to one Ge2+ atom. In the third H+0.50- site, H+0.50- is bonded in a single-bond geometry to one Ge2+ atom. In the fourth H+0.50- site, H+0.50- is bonded in a single-bond geometry to one Ge2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeH4 by Materials Project

GeH4 crystallizes in the monoclinic P2_1/m space group. The structure is one-dimensional and consists of two hydrogen molecules and two GeH2 ribbons oriented in the (0, 0, 1) direction. In each GeH2 ribbon, Ge2+ is bonded in a bent 150 degrees geometry to two H+0.50- atoms. There are one shorter (2.17 Å) and one longer (2.18 Å) Ge–H bond lengths. There are two inequivalent H+0.50- sites. In the first H+0.50- site, H+0.50- is bonded in a single-bond geometry to one Ge2+ and one H+0.50- atom. The H–H bond length is 0.80 Å. In the second H+0.50- site, H+0.50- is bonded in a single-bond geometry to one Ge2+ and one H+0.50- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GeH4 by Materials Project

GeH4 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of four hydrogen molecules and two GeH2 ribbons oriented in the (0, 0, 1) direction. In each GeH2 ribbon, Ge2+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent H+0.50- atoms. There is two shorter (1.68 Å) and two longer (2.00 Å) Ge–H bond length. H+0.50- is bonded in a water-like geometry to two equivalent Ge2+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1982

An estimate of the PH3, CH3D, and GeH4 abundances on Jupiter from the Voyager IRIS data at 4.5 microns

No evidence is found for large scale phosphine abundance variations over Jovian latitudes between -30 and +30 deg, in PH3, CH3D, and GeH4 abundances derived from the 2100-2250/cm region of the Voyager 1 IRIS spectra. The PH3/H2 value of (4.5 + or - 1.5) X 10 to the -7th derived from atmospheric regions corresponding to 170-200 K is 0.75 + or - 0.25 times the solar value, and suggests that the PH3/H2 ratio on Jupiter decreases with atmospheric pressure upon comparison with other PH3 determinations at 10 microns. In the 200-250 K region, CH3D/H2 and GeH4/H2 ratios of 2.0 X 10 to the -7th and 1.0 X 10 to the -9th, respectively, are derived within a factor of 2.0. Assuming a C/H value of 0.001, as derived from Voyager, the CH3D/H2 ratio obtained in this study implies a D/H ratio of 0.000018. This is in agreement with the interstellar medium value.

Drossart, P.↗
NASA NTRS1990

Detection Of Gas-Phase Polymerization in SiH4 And GeH4

Inelastic scattering of laser light found to indicate onset of gas-phase polymerization in plasma-enhanced chemical-vapor deposition (PECVD) of photoconductive amorphous hydrogenated silicon/germanium alloy (a-SiGe:H) film. In PECVD process, film deposited from radio-frequency glow-discharge plasma of silane (SiH4) and germane (GeH4) diluted with hydrogen. Gas-phase polymerization undesirable because it causes formation of particulates and defective films.

Shing, Yuh-Han↗
NASA NTRS1990

All-electron molecular Dirac-Hartree-Fock calculations: The group 4 tetrahydrides CH4, SiH4, GeH4, SnH4 and PbH4

A basis-set-expansion Dirac-Hartree-Fock program for molecules is described. Bond lengths and harmonic frequencies are presented for the ground states of the group 4 tetrahydrides, CH4, SiH4, GeH4, SnH4, and PbH4. The results are compared with relativistic effective core potential (RECP) calculations, first-order perturbation theory (PT) calculations and with experimental data. The bond lengths are well predicted by first-order perturbation theory for all molecules, but non of the RECP's considered provides a consistent prediction. Perturbation theory overestimates the relativistic correction to the harmonic frequencies; the RECP calculations underestimate the correction.

Dyall, Kenneth G.↗
NASA NTRS1991

All-electron molecular Dirac-Hartree-Fock calculations - The group IV tetrahydrides CH4, SiH4, GeH4, SnH4, and PbH4

A basis-set-expansion Dirac-Hartree-Fock program for molecules is described. Bond lengths and harmonic frequencies are presented for the ground states of the group 4 tetrahydrides, CH4, SiH4, GeH4, SnH4, and PbH4. The results are compared with relativistic effective core potential (RECP) calculations, first-order perturbation theory (PT) calculations and with experimental data. The bond lengths are well predicted by first-order perturbation theory for all molecules, but none of the RECP's considered provides a consistent prediction. Perturbation theory overestimates the relativistic correction to the harmonic frequencies; the RECP calculations underestimate the correction.

Dyall, Kenneth G.↗
NASA NTRS1991

The spectrum of Saturn from 1990 to 2230/cm - Abundances of AsH3, CH3D, CO, GeH4, NH3, and PH3

An analysis is presented of the abundances and vertical distributions of all known absorbers in the 5-micron spectrum of Saturn, in view of previously unpublished observations, synthetic spectra of each atmospheric constituent, and an atmospheric model for synthesizing Saturn's spectrum in order to make comparisons with observations. The model used encompasses the abundances of all gaseous absorbers, their vertical distributions, clouds, and the thermal and reflected solar components of planetary flux. A coherent understanding is in this way obtained of both the many variables affecting Saturn's 5-micron spectrum and the similarities between Jupiter and Saturn.

Noll, Keith S.↗
NASA NTRS1976

Scattering of high-velocity He and Ar beams by methane, silane, and germane

Fast He and Ar beams have been scattered by room-temperature CH4, SiH4, and GeH4 to obtain average atom-molecule potentials for He-CH4, He-SiH4, He-GeH4, Ar-CH4, and Ar-GeH4. Somewhat unexpectedly, the potential for He-GeH4 was intermediate between He-CH4 and He-SiH4; this apparent discrepancy, however, correlates with the bond polarities. The potential for Ar-CH4 can be satisfactorily predicted from that for He-CH4 by means of simple potential models and combination rules. The analogous prediction for Ar-GeH4 is unsatisfactory; reasons for the discrepancy are discussed.

Amdur, I.↗
NASA NTRS1978

Germane in the atmosphere of Jupiter

Germane, GeH4, is a tetrahedral molecule like methane. The nu 3 fundamental mode of GeH4 falls in the middle of the 5-micrometer Jupiter window. Jupiter observations were made in December 1975 during three flights with the 0.9-m telescope of the Kuiper Airborne Observatory. The spectrometer is a rapid-scanning Michelson interferometer having InSb detectors at each of the two outputs. The germane identification procedure is based on a comparison of the obtained Jupiter spectrum with that of laboratory germane. It appears that the detection of GeH4 in Jupiter's atmosphere with a mixing ratio of 0.6 ppb is the smallest concentration of a trace constituent yet detected in a nonterrestrial planetary atmosphere. It is pointed out that a strict interpretation of thermochemical equilibrium predictions for the spectral line forming regions of Jupiter's atmosphere does not explain the observation of GeH4.

Fink, U.↗
NASA NTRS1988

Diagnostics of silane and germane radio frequency plasmas by coherent anti-Stokes Raman spectroscopy

In situ plasma diagnostics using coherent anti-Stokes Raman spectroscopy have shown different dissociation characteristics for GeH4 and SiH4 in radio frequency (rf) plasma-enhanced chemical vapor deposition of amorphous silicon germanium alloy (a-SiGe:H) thin films. The GeH4 dissociation rate in rf plasmas is a factor of about 3 larger than that of SiH4. Plasma diagnostics have revealed that the hydrogen dilution of the SiH4 and GeH4 mixed plasma plays a critical role in suppressing the gas phase polymerization and enhancing the GeH4 dissociation.

Perry, Joseph W.↗
NASA NTRS1988

Silane and germane plasma diagnostics for depositing photosensitive a-SiGe:H films

Highly photosensitive a-SiGe:H films with a light-to-dark conductivity ratio of 8 x 103 and an optical bandgap of 1.40 eV have been produced by RF glow discharge using hydrogen dilution of SiH4 and GeH4 mixed gas plasma. The critical role of hydrogen dilution in GeH4 containing plasmas is to suppress the gas-phase polymerization and promote the incorporation of Ge into the film. It is observed that inelastic laser light scattering of the RF plasma is a sensitive method for monitoring the onset of the gas-phase polymerization. In situ coherent anti-Stokes Raman spectroscopy measurements have shown that the dissociation rate of GeH4 is a factor of three larger than that of SiH4.

Shing, Y. H.↗
NASA NTRS1979

Thermodynamics of selected trace elements in the Jovian atmosphere

The thermochemistry of several hundred compounds of twelve selected trace elements (Ge, Se, Ga, As, Te, Pb, Sn, Cd, Sb, Tl, In, and Bi) has been investigated for solar composition material along a Jupiter adiabat. The results indicate that AsF3, InBr, TlI, and SbS, in addition to CO, PH3, GeH4, AsH3, H2Se, HCl, HF, and H3BO3 proposed by Barshay and Lewis (1978), may be potential chemical tracers of atmospheric dynamics. The reported observation of GeH4 is interpreted on the basis of new calculations as implying rapid vertical transport from levels where the temperature is greater than or equal to 800 K. Upper limits are also set on the abundances of many gaseous compounds of the elements investigated.

Fegley, B., Jr.↗
NASA NTRS1993

The reaction of atomic hydrogen with germane - Temperature dependence of the rate constant and implications for germane photochemistry in the atmospheres of Jupiter and Saturn

Studies of the formation and loss processes for GeH4 are required in order to provide data to help determine the major chemical form in which germanium exists in the atmospheres of Jupiter and Saturn. The reaction of hydrogen atoms with germane is one of the most important of these reactions. The absolute rate constant for this reaction as a function of temperature and pressure is studied. Flash photolysis of dilute mixtures of GeH4 in argon, combined with time-resolved detection of H atoms via Lyman alpha resonance fluorescence, is employed to measure the reaction rate. The reaction is shown to be moderately rapid, independent of total pressure, but possessing a positive temperature dependence.

Nava, David F.↗