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The interactions of Cu(2S:3d104s1, 2D:3d94s2, and 2P:3d104p1) with SiH4 and GeH4 were studied by means of Hartree–Fock–SCF and multiconfigurational-SCF followed by variational and multireference second order Moller–Plesset perturbational configuration interaction (CIPSI) calculations, using relativistic effective core potentials. The Cu atom in its 2P(3d104p1) state is inserted in the Si–H and Ge–H bonds. In both interactions their corresponding 5 2A′ potential energy surfaces are initially attractive and become repulsive only after having encountered the avoided crossing region with the initially repulsive 4 2A′ surface adiabatically linked with the Cu(2D:3d94s2)–SiH4(GeH4) fragments. The three 2A′ curves derived from the interaction of the Cu(2D:3d94s2) atom with silicon (or germane) molecule are initially repulsive. Each one of them shows two avoided crossings and its lowest lying 2 2A′ curve goes sharply down until it meets the X 2A′ curve adiabatically linked with the Cu(2S:3d104s1)+SiH4(GeH4) asympt...

The interaction of Cd(1S:5s2, 3,1P:5s15p1) and Hg(1S:6s2, 1,3P:6s16p1) with GeH4 were studied by means of Hartree–Fock self-consistent field (SCF) and multiconfigurational SCF plus variational and multireference second order Moller–Plesset perturbational configuration interaction (CIPSI) calculations, using relativistic effective core potentials. It was found that both metal atoms in their 3P(ns1np1) state break spontaneously the Ge–H bond of the germane molecule, giving place to the MH+GeH3 (M=Cd, Hg) final products. For both atoms, the 1P(ns1np1) state is also inserted in the Ge–H bond and the corresponding interaction surface shows an avoided crossing with the lowest-lying X 1A′ potential surface adiabatically linked with the M(1S:ns2)+GeH4. This interaction leads eventually to the MH+GeH3 products. The HMGeH3 X 1A1 (M=Cd, Hg) intermediate molecules, diabatically correlated with the M(1P:ns1np1)+GeH4, which lie 13.6 and 21 kcal/mol, respectively, above the ground state reactants, have been carefully ch...

Complete polarizabilities and first hyperpolarizabilities (which include zero-point-vibrational averaging and other vibrational corrections) have been calculated at the self-consistent-field and Moller–Plesset second order perturbation levels of approximation for CH4, CF4, and CCl4. As well as the static values, α(−ω;ω), β(−ω;ω,0), and β(−2ω;ω,ω) have also been determined. The values of β(−2ω;ω,ω) for CCl4 are germane to a proposed standard for the determination of nonlinear optical properties in solution. For CCl4, our best estimate of β(−2ω;ω,ω) at ℏω = 0.040 a.u. is 13.6 a.u., the experimentally-derived gas value at ℏω = 0.043 a.u. is 20.7± 1.6 a.u. This latter value has been used to substantiate the proposed liquid phase value.

The spectroscopy and excited state dynamics of A 1B1 germylene (GeH2) have been investigated experimentally and theoretically. Jet‐cooled laser‐induced fluorescence spectra of GeH2 were obtained by subjecting germane (GeH4) to an electric discharge at the exit of a pulsed nozzle. The band origins of ten vibronic transitions were determined, giving values for the upper state fundamentals of ν1=783.0 cm−1 and ν2=1798.4 cm−1. Sufficient numbers of 000 band rovibronic transitions were observed to give the ground and excited state structures as r″=1.591(7) A, θ″=91.2(8)° and r′=1.553(12) A, θ′=123.4(19)°. Fluorescence lifetime measurements show that the 00,0 rotational levels decay radiatively; higher J rotational states in the 00 vibronic level decay much faster, due to a heterogeneous predissociation in the excited state. High quality ab initio studies are consistent with a model in which the lower vibronic levels of the A state predissociate through the a 3B1 state to produce Ge(3P)+H2(1Σ+g). The transit...

Eight protonated germane structures (GeH+5) were examined in detail using the self‐consistent field (SCF), configuration interaction including single and double excitations (CISD), and coupled cluster including single, double, and perturbatively included triple excitations [CCSD(T)] methods in conjunction with a double‐ζ plus polarization (DZP) and a triple‐ζ plus polarization (including f functions on germanium TZP+f) basis set. The C4v and the D3h isomers are high in energy [84 and 48 kcal mol−1, respectively, relative to the Cs(I) structure at DZP SCF]. Although structure Cs(I) is the global minimum, both Cs structures, where GeH+5 is comprised of a nearly planar germyl cation and a hydrogen molecule, are essentially equal in energy and allow virtually free hydrogen moiety rotation. Complete hydrogen scrambling does not occur, as the energy of the C2v(I) structure [33 kcal mol−1 (TZP+f CCSD)] is higher than the dissociation energy of GeH+5 into GeH+3 and H2 (D0=10 kcal mol−1). D0 of GeH+5 is almost the...

Optical microscopy, spectroscopic and x-ray diffraction studies at high-pressure are used to investigate intermolecular interactions in binary mixtures of germane (GeH(4)) + hydrogen (H(2)). The measurements reveal the formation of a new molecular compound, with the approximate stoichiometry GeH(4)(H(2))(2), when the constituents are compressed above 7.5 GPa. Raman and infrared spectroscopic measurements show multiple H(2) vibrons substantially softened from bulk solid hydrogen. With increasing pressure, the frequencies of several Raman and infrared H(2) vibrons decrease, indicating anomalous attractive interaction for closed-shell, nonpolar molecules. Synchrotron powder x-ray diffraction measurements show that the compound has a structure based on face-centered cubic (fcc) with GeH(4) molecules occupying fcc sites and H(2) molecules likely distributed between O(h) and T(d) sites. Above ca. 17 GPa, GeH(4) molecules in the compound become unstable with respect to decomposition products (Ge + H(2)), however, the compound can be preserved metastably to ca. 27 GPa for time-scales of the order of several hours.

Deexcitation cross sections of Ar(3P2), Ar(3P1), Ar(3P0), and Ar(1P1) by CH4, SiH4, and GeH4 have been measured. The cross section values obtained are largely dependent on both the electronic states of excited argon atoms and the target molecules. The magnitude of these values is discussed in terms of energy transfer mechanisms or interactions responsible for the deexcitation transition. In the deexcitation of the metastable atoms, Ar(3P2) and Ar(3P0), the magnitude of the cross sections is mainly ascribed to the adiabatic transition from the interaction potentials for Ar*–M (M=CH4, SiH4, and GeH4 ) to those for Ar–M* due to a long‐range potential curve crossing, while in the deexcitation of the resonant atoms, Ar(3P1) and Ar(1P1), the magnitude is mainly ascribed to resonant energy transfer due to a long‐range dipole–dipole interaction.

The product channels in reactions of metastable Ar(3P2) and He(23S) atoms and Ar+, (Ar+)*, He+, and He+2 ions with GeH4 have been studied by observing emission spectra in the flowing afterglow and beam apparatus. H*, Ge*, GeH(A 2Δ–X 2Π), and GeH+(a 3Π0+,1–X 1Σ+) emissions were observed in the 190–600 nm region. The effect of SF6 addition into the discharge flow indicated that secondary electron‐ion recombination processes participate in the formation of Ge* and GeH(A) in the Ar and He afterglows. The formation of Ge* through the Ar+/GeH4 reaction followed by electron‐ion recombination processes was confirmed by simultaneous formation of Ar+ and low‐energy electrons through the He(2 3S)/Ar Penning ionization. The total emission rate constants were determined to be 8.6 and 0.15×10−12 cm3 s−1 for Ge* and GeH(A) in the Ar(3P2)/GeH4 reaction, and 0.068 and 5.8×10−12 cm3 s−1 and for H* and Ge* in the He(2 3S)/GeH4 reaction, respectively.

In recent years there have been extensive experimental searches for bond selectivity. However, actual energy localization has not been achieved due to very fast intramolecular vibrational relaxation (IVR). We have recently reported [Zhu, Thrush, and Robiette, Chem. Phys. Lett. 150, 181 (1988)] the spectrum of (3000) stretching overtone band of germane near 6130 cm−1 in which the transition exhibits striking pseudosymmetric‐top structure. A detailed analysis is presented here. The P, Q, and R branches with J up to 10 were assigned, and molecular constants of (3000) state were derived for 74GeH4, 72GeH4, and 70GeH4. The results indicate that the (3000) state of germane is very near the local mode limit and that physically the molecule can be thought of as vibrating with the three GeH stretching quanta localized in one bond. Since there are no strong couplings between this state and any other state, the energy will only be slowly delocalized by the IVR process.

Ten ro–vibrational transitions in the ν2 fundamental of germane, GeH4, have been investigated with a tunable sideband laser. The isotope effect, i.e., the fivefold occurence of each transition due to the natural germanium isotopes, has been clearly resolved. From the observation of a combination difference the ground state centrifugal distortion constant Dt is determined to 67.6±0.4 kHz for two molecular isotopes separately. The dependence of other molecular constants on the isotope mass is shown. The worst‐case error in absolute frequency measurement is about 18 MHz while the relative accuracy is believed to be better than 5 MHz for most of the lines observed.

Microwave spectra of five isotopic species of CF3GeH3 have been investigated in the region 15 000 to 31 000 MHz. The height of the potential barrier hindering the internal rotation was determined to be 1280±150 cal/mole, using the frequency method for rotational satellite transitions. The sym‐sym case of hindered internal rotor molecules is discussed, and expressions are given for calculating barrier heights using tabulated quantities.

The infrared emission intensities from the reaction F+GeH4 have been used to measure the energy partitioned to the HF product. The experiments were conducted in a cold‐walled reactor with various flow rates of GeH4 and fluorine atom source (discharged SF6 or CF4). Based on the highest observed HF vibrational‐rotational level, D(H–GeH3) was estimated as ≤78 kcal mole−1. The initial relative vibrational populations were N(ν = 1): N(ν = 2): N(ν = 3): N(ν = 4): N(ν = 5) = 0.10:0.18:0.29:0.41: 0.02. Based upon D(H–GeH3) = 78 kcal mole−1, the mean fractional conversion of energy into HF vibrational energy was 0.58. The rotational distributions extend to quite high J levels; after correction for some rotational relaxation the mean fractional conversion to HF rotational energy was estimated as 0.12.

Electron impact spectra of silane and germane have been recorded using electrons of 200 eV incidence at scattering angles of ∼2°–9°. The range of energy losses covers the entire region of single electron excitation from the valence shell. In the bound state spectrum evidence is presented supporting the existence of two valence transitions in addition to anticipated s, p, and d Rydberg transitions. The 9° spectra reveal much structural detail in the ∼4 eV energy range preceding the 2A1 ion state. The most prominent band consists of a superposition of an optically allowed valence excitation and a symmetry forbidden Rydberg transition. The remaining peaks may be members of vibrational progressions belonging to either [d(t2), a1], [p, a1] ← (a1)2 dipole allowed or [d(e), a1], [s,a1] ← (a1)2 dipole forbidden channels. Of these two possibilities the evidence presented here favors the latter choice.

The microwave spectra from 26.5 to 39.0 GHz of eighteen isotopic species of methylgermyl bromide, 12CH3GeH2Br, 12CH3GeD2Br, and 13CH3GeH2Br for three of the naturally occurring isotopes of germane, 70Ge, 72Ge, and 74Ge, as well as the two of bromine, 79Br and 81Br, have been measured and assigned. From these data, substitution structural parameters were determined except for the methyl group. The determined parameters are: r(Ge–Br)=2.308±0.002 A, r(Ge–C)=1.933±0.002 A, r(Ge–H)=1.520±0.001 A, r(C–Hs)=1.100±0.012 A, r(C–Ha)=1.097±0.030 A, CGeBr=107.0±0.2°, HGeH=111.5±0.1°, HGeC=112.2±0.1°, GeCHs=110.3±4.7°, and GeCHa=111.9±1.7°. From a diagnostic least‐squares adjustment to fit 36 rotational constants, r0 structural parameters were also obtained. Quadrupolar coupling constants have been obtained. These results are compared to similar quantities in some related molecules.

The heat capacity of solid germane, GeH4, has been measured over the range 2.8 K

HF complexes with methane, silane, and germane were prepared in noble gas matrices and studied using infrared spectroscopy and Hartree–Fock (SCF) calculations. The spectra indicate that two types of 1:1 complexes were formed, a normal one in which the hydrogen of HF is interacting with one hydrogen of silane or germane, and a reverse complex in which the fluorine of HF is interacting with one hydrogen atom of methane. The IR inactive symmetric C–H stretch in CH4 was observed in the CH4‐‐FH complex as a weak band at 2914 cm−1. In the silane‐‐HF and germane‐‐HF complexes, the Si–H and Ge–H stretches were perturbed approximately 50 cm−1 to higher energy relative to the antisymmetric stretch ν3 in each parent molecule, but the ν1 modes were masked by the strong ν3 parent bands. Higher order 1:2 (AH4:HF) complexes were also observed and support the normal or reverse‐type geometry of the 1:1 complexes.

Relative photodetachment cross sections have been determined for the silyl and germyl anions (SiH3−, GeH3−) in the wavelength ranges 400.0–870.0 nm (3.10–1.43 eV) and 400.0–720.0 nm (3.10–1.72 eV), respectively. An ion cyclotron resonance spectrometer was used to generate, trap, and detect the negative ions, and a 1000 W xenon arc lamp with a grating monochromator was employed as the light source. Both ions exhibited cross sections behaving sigmoidally over the wavelength ranges studied. These experiments afford the following electron affinities: E.A. (SiH3·) ≤1.44±0.03 eV and E.A. (GeH3·) ≤ 1.74±0.04 eV. From estimates of proton transfer equilibrium constants, bond energies are approximated for silane and germane.

Microwave spectra of three isotopic species of CH2FGeH3 have been investigated in the region 8000–30 000 MHz. The height of the potential barrier hindering the germyl group (GeH3) internal rotation was determined to be 1390±40 cal/mole from measured A‐E frequency differences, using a PAM calculation through fourth‐order perturbations. Dipole moment components μa = 1.00 D, μb = 1.30 D, giving a resultant μ = 1.64±0.03 D, were obtained from Stark effect measurements. A technique for assigning R‐branch asymmetric rotor transitions is discussed.

The vacuum ultraviolet absorption cross sections of SiH4, GeH4, Si2H6, and Si3H8 are reported for the wavelength region 107–220 nm using synchrotron radiation as a light source. Absorption maxima of these compounds were found at the exciting wavelengths of 115–119 nm. Broad peaks observed were mostly assigned as primarily Rydberg transitions of the σSiH and σSiSi bonding electrons to the 4s, 4p, and 4d orbitals. The absorption features of germane resemble those of monosilane. In the photoexcitation of monosilane, the emission of the SiH(A 2Δ→X 2Π) transition was observed and its onset was found to be 132±2nm. The absorption spectrum of disilane showed five peaks. They were mostly assigned as 2a1g→4s, 2a1g→np(n=4−6) transitions and the strongest band was overlapped by 1eg→4d and 1eu→4p Rydberg transitions. In trisilane molecules three very weak and broad peaks were recognized and assigned as 3b2→4s, 4p and 4a1→4s, 4d Rydberg transitions. The strongest band was tentatively assigned as the superposition of...

The microwave spectra have been recorded from 18.0 to 26.5 GHz for 12CH3GeH212C14N, 13CH3GeH212C14N, 12CH3GeH212C15N, 12CH3GeH213C14N, 12CH3GeD212C14N, and 12CD3GeH212C14N of the four naturally occurring isotopes of germane: 70Ge, 72Ge, 74Ge, and 76Ge. Only a‐type transitions were observed and R‐branch assignments have been made for all the isotopic species in the ground vibrational state from which the rotational constants were determined. From these data the complete structural parameters were determined to be r0(CME–Ge)=1.933±0.002 A, r(Ge–CCN)=1.927±0.004 A, r(C≡N)=1.155±0.004 A, r(Ge–H)=1.521±0.001 A, r(C–Hs)=1.092±0.005 A, r(C–Ha)=1.092±0.005 A, ∢CGeC=107.36°±0.60°, ∢HGeH=111.41°±0.04°, ∢HGeCMe=112.92°±0.08°, ∢HsCGe=109.5°±2.0°, and

The J=0→1 and 1→2 transitions of 28 isotopic species of CH3GeH3 have been measured. From the rotational constants obtained, the following structural parameters have been calculated: rCH=1.083±0.005 A°, rGeH=1.529±0.005 A°, rCGe=1.9453±0.0005 A°, ≰HCH=108°25′±30′, ≰HGeH=109°15′±30′. The K=1 transitions of the asymmetrically deuterated species are split by internal rotation about the C–Ge bond. Withthe assumption of a threefold sinusoidal potential, an internal barrier of 1239±25 cal/mole has been determined from these splittings. Analysis of the Stark effect of several species gives a dipole moment of 0.635±0.006 D. From observed hyperfine structure the nuclear quadrupole coupling constant of Ge73 has been calculated to be +3 Mc.

An electron spectrometer which employs double focusing electrostatic plates is described. The photoelectron spectra obtained by bombarding methane, silane, germane, methyl fluoride, difluoromethane, and trifluoromethane with 21.22‐eV photons are presented. The experimental ionization energies are compared with theoretical and other experimental data, and molecular‐orbital assignments are made for the energy values obtained. Broad double maximum bands were observed in the case of methane, silane, and germane and are discussed in terms of Jahn–Teller distortion for the positive ions. Possible correlation of the methane spectrum with interstellar space data is also discussed.

The vacuum‐ultraviolet photolysis of germane and the four deuterogermanes isolated in an argon matrix at temperatures between 4 and 25°K produces significant concentrations of several reactive species. Absorptions at 1839, 1813, 928, and 850 cm−1 have been assigned to a pyramidal GeH3 molecule and those at 1887, 1864, and 920 cm−1 have been assigned to a nonlinear GeH2 molecule. Digermane and the products of its photolysis are also produced and contribute considerably to the infrared spectra in the region below 1000 cm−1.

The infrared spectra of gaseous CH3GeH3, CD3GeH3, and CH3GeD3 were observed in the range 4000–400 cm—1. The 12 fundamental frequencies for each molecule are assigned to normal modes and the spectra are discussed in some detail. Teller—Redlich product‐rule ratios support the assignments. The height of the barrier hindering internal rotation was found from measurements on twelve combination bands involving the torsional modes to have an average value of 1270 cal/mole. The torsional force constant was estimated to be 0.31×10—12 erg/rad. The corresponding barrier height and torsional force constant for methylsilane were estimated to be 1715 cal/mole and 0.44×10—12 erg/rad, respectively, from published data.Analyses of the rotational structures of ν7–10 and of ν12 and 2ν12 in the spectrum of CH3GeH3 and of ν7–10 and ν12 in the spectrum of CD3GeH3 afforded values for the band origins, certain rotational constants and ζ7–12 for both molecules.

A Coriolis perturbation on the rotational structure of the fundamental frequency, v4 has been computed for silane and germane. Matrix elements of the Coriolis operator, A for the lines P(9), P(10) and Q(10) have also been obtained. The envelope of the resulting absorption curve has been compared with the experimental curve and good agreement found. The most striking difference in the two spectra is that in the case of silane, the Q branch degrades toward lower frequencies and in germane, towards higher frequencies. This is shown to be due to the relative position of the infra‐red inactive frequency, v2 to which the perturbation is due.

The ultraviolet emission spectrum of GeH has been examined following the two photon‐initiated dissociation of germane (GeH4) at 248 nm. The most prominent peaks lying between ∼250 and 340 nm are tentatively assigned to B 2Σ(v′=0)→X 2Π1/2,3/2 (v′) transitions. From this premise, the vibrational constants for the X 2Π states have been estimated to be ωe=(1949±5) cm−1, ωexe=16.5±2.0 cm−1, and ωeye=(0.7±0.3) cm−1. Also, the radiative lifetime of the lowest vibrational levels of the GeH A 2Δ state in transitions to ground has been measured to be 12±2 ns.

The radicals formed by the reaction of GeH4 with H in the Xe matrix were investigated by electron spin resonance (ESR) spectroscopy at very low temperatures. The radicals observed were identified as GeH3 and GeH5. The newly observed radical GeH5 is considered as the intermediate of the reaction H+GeH4→H2+GeH3. The ESR parameters of these radicals were determined by numerical deconvolution of the observed spectra.

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.

From measurements of the pure rotational transitions in trichloro germane, the rotational constants B0 (in megacycles/sec) for the various isotopic modifications of the molecule were found to be: 2172.75 for HGe70Cl335, 2169.26 for HGe72Cl335, 2165.84 for HGe74Cl335, 2063.74 for HGe70Cl337, 2060.43 for HGe72Cl337, and 2057.20 for HGe74Cl337. The calculated structure from the above data for the molecule in the ground state is: dGeH=1.55±0.04A, dGeCl=2.1139±0.0010A, and ∠ClGeCl=108°17′±12′. Rotational lines for the molecule when it is in the two excited GeCl3 deformation vibrations are also measured and the corresponding molecular structures calculated.