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1.
An ion-beam apparatus is employed to study the reaction of Ni+ with H2, HD, and D2 as a function of kinetic energy. These reactions lead to the endothermic formation of NiH+, NiH+ and NiD+, and NiD+, respectively. Interpretation of the threshold for these processes yields the average bond energies, D0(Ni+H) = 1.86 ± 0.09 eV and D0(Ni+D) = 1.90 ± 0.14 eV. The total reaction cross sections for all three systems are similar; however, a striking isotope effect is observed for Ni+ reacting with HD. The dependence of the cross sections on relative kinetic energy is discussed in terms of simple models for reaction. 相似文献
2.
The tandem quadrupole photodissociation mass spectrometer has been used to study photodissociation reactions of Ar+2, Ne+2, and (CO2)+2. The cross sections for photodissociation of Ar+2 exhibited a strong dependence on ion source pressure, varying from 2 × 10 ?18cm2 at 0.1 torr to 6 × 10?19cm2 at 0.5 torr. A large photodissociation cross section (2 × 10?17cm2 for the reaction (CO2)+2 → CO+2+ CO2 was observed at the red end of the visible spectrum (580–620 nm) suggesting that this may be an important reaction in CO2 rich planetary ionspheres such as that of Mars. 相似文献
3.
The fragmentation of metastable NH+3 ions and isotopic analogs via the reaction NH+3 → NH+2 + H has been investigated using mass analysed ion kinetic energy spectrometry (MIKES). Kinetic energy release distributions and the metastable intensity were measured as a function of ion source temperature. Both the average kinetic energy release and the metastable intensity increase with ion source temperature. The data are consistent with the metastable reaction arising from tunneling through a rotational barrier. The experimental data are compared with the predictions of a tunneling model. 相似文献
4.
Collisionally activated decompositions and ion-molecule reactions in a triple-quadrupole mass spectrometer are used to distinguish between cis- and trans-1,2-cyclopentanediol isomers. For ion kinetic energies varying from 5 eV to 15 eV (laboratory frame of reference), qualitative differences in the daughter ion spectra of [MH]+ are seen when N2 is employed as an inert collision gas. The cis ?1,2-cyclopentanediol isomer favors H2O elimination to give predominantly [MH- H2O]+. In the trans isomer, where H2O elimination is less likely to occur, the rearrangement ion [HOCH2CHOH]+ exists in significantly greater abundance. Ion-molecule reactions with NH3 under single-collision conditions and low ion kinetic energies can provide thermochemical as well as stereochemical information. For trans ?1,2-cyclopentanediol, the formation of [NH4]+ by proton transfer is an exothermic reaction with the maximum product ion intensity at ion kinetic energies approaching 0 eV. The ammonium adduct ion [M + NH4]+ is of greater intensity for the trans isomer. In the proton transfer reaction with the cis isomer, the formation of [NH4]+ is an endothermic process with a definite translational energy onset. From this measured threshold ion kinetic energy, the proton affinity of cis ?1,2-cyclopentanedioi was estimated to be 886 ± 10 kJ mol?1. 相似文献
5.
Grady D. Carney 《Chemical physics letters》1981,78(1):200
Ab initio calculated values of fundamental vibrational frequencies and zero-point energies are presented for HTD+, D2T+, T2D+, H2T+, T2H+ and T+3. 相似文献
6.
O.J. Orient 《Chemical physics letters》1977,52(2):264-269
The mobilities of mass-identified H+3 and HeH+ ions in helium and the reaction rate coefficient for HeH+ + H2 → H+3 + He have been measured by a drift-tube quadrupole mass spectrometer at 300 K. The zero-field reduced mobilities of H+3 and HeH+ ions, corrected to 273 K, are 31.0 ± 0.8 and 23.4 ± 0.6 cm2 V?1 s?1 respectively. The reaction rate coefficient was found to be (1.26 + 0.16) × 10?9 cm3s?1 and was observed to be independent of the mean ion kinetic energy in the range from 0.04 to 0.3 eV. 相似文献
7.
Photodissociation reaction CO?3 + hv → CO2 + O? has been observed at seven photon energies between 2.35 and 2.71 eV using a drift tube mass spectrometer and an argon ion laser. The total cross sections for the destruction of CO?3 due to photons of these energies have been measured, and it is concluded that essentially all of this destruction is due to photodissociation. The photodestruction of CO?3.H2O has also been observed at four photon energies. 相似文献
8.
A photoelectron-photoion coincidence technique is used to measure the internal-energy dependence of the ion-molecule reaction NH3+(Eint+NH3 → NH4+ + NH2 at thermal collision energy. The range in which the internal energy is varied, is enlarged by including in the experiment the electronically excited state of the NH3+ ion. Special attention is paid to the possible influence of the product's kinetic energy on the measurements. The experimental results are analysed using a modified statistical model and compared with previous data. 相似文献
9.
The sequential impulse model for direct reactions of Mahan, Ruska and Winn is extended to include endothermic reactions. The model is outlined and used to predict the variation in cross section with kinetic energy for heavy atom—light homonuclear diatom reactions. The results are found to agrees well with experimental data for the reaction Ba+(D2, D)BaD+. The bond dissociation energy of BaD+, 2.5 ± 0.1 eV, and the proton affinity of Ba, 250 ± 3 kcal/mol, are derived. 相似文献
10.
Reaction and charge transfer of H+2 + Ar to give ArH+ and Ar+ have been investigated as a function of H+2 vibrational quantum state and kinetic energy (Ec.m.), using photoionization and guided beam ion optics. Resonance effects are important in charge transfer; proton and charge transfer are closely coupled for Ec.m. 3 eV. 相似文献
11.
Integral scattering cross sections have been measured for alkali ions (Li+, Na+ and K+) in the energy range 500–4000 eV scattered by room temperature N2 and CO molecules through effective laboratory angles greater than 5 × 10?3 rad. The repulsive potentials deduced from the cross sections are represented bya practically identical formula for the Na+N2 and Na+CO systems, and for the K+CO systems, respectively, while the repulsive potentials of the Li+N2 system are somewhat smaller than those of the Li+CO system at larger intermolecular distances. 相似文献
12.
The collisionally induced dissociation of CH2Br+2 to yield CH2Br+ + Br has been investigated by photoelectronphotoion coincedence spectroscopy in which nominally zero kinetic electrons were detected. The reactant CH2Br+2 ions were produced by photoionzation with intenal energies of 0.0, 0.20 and 0.60 eV. For all three internal energies, the kinetic energy threshold for dissociation is just equal to the energy defect. 相似文献
13.
Some geometric configurations of the OH+4 and FH+3 ions have been calculated by the SCF MO LCAO method using linear combinations of gaussian lobe functions. The total electronic energies of the systems under study are lower than the sum of the energies for H2O and H+2 or OH+3 and H, and HF and H+2 or FH+2 and H, respectively. 相似文献
14.
Integral reactive cross sections for chemi-ionization have been measured in a crossed-beam experiment for Ba, Sr + SF6 → BaF+, SrF+ + SF5? and Ca, Sr + NF3 → CaF+, SrF+ + NF2? at collision energies Ec.m. < 4 eV. The experimental results confirm a collision complex. The applicability of RRKM theory to chemi-ionization of polyatomic molecules is discussed. The presence of competing neutral-product reactions, included in the calculation, is important for the determination of dynamical and statistical properties of the intermediate states formed. The slope of the chemi-ionization cross section as a function of collision energy indicates directly that all vibrational degrees of freedom are activated. 相似文献
15.
The preparations of CH2SF4 and CH3CHSF4 are presented and the structures are discussed. Addition reactions of polar species give a wide range of new compounds, like Hg(CH2SF5)2, F4AsCH2SF5, cisBrSF4CH3, cisF5SeOSF4CH2Br, a.o. While CH2SF4 decomposes at room temperature slowly to CH2CH2 and SF4, at high temperatures HF and CSF2 are formed. CH3CHSF4 gives mainly CH3CHF2 at room temperature. The “saturated” compounds CH3SF5 and C2H5SF5 have been prepared. They react with SbF5 in SO2 at low temperatures to form the cations CH3SF4+ and C2H5SF4+. The CH3SF4+ ion has been investigated in detail by nmr methods at low temperatures. It decomposes to CH3 and SF4, which react further in the SO2/SbF5 system to CH3OSO+ and SF3+. 相似文献
16.
Christopher M. Johnson Mark G. Shilton Arthur T. Howe 《Journal of solid state chemistry》1981,37(1):37-43
We have measured the ionic conductivities of pressed pellets of the layered compounds MUO2PO4 · nH2O, and correlated the results with TGA data. The conductivities (in ohm?1 m?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li+4H2O, 10?4; Li+, Na+, K+, and NH4+3H2O, 10?4, 10?2, 10?4, and 10?4; H+, Li+, and Na+1.5H2O, 10?2, 10?4, and 10?4; Na+1H2O, 10?5; H+, K+, and NH4+0.5H2O, all 10?5; and H+, Li+, Na+, K+, NH+4, and , 10?5, 10?5, 10?4, 10?5, 10?5, and 10?6. A ring mechanism is proposed to account for the high conductivity found in NaUO2PO4 · 3.1H2O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO2PO4(A ? x)H2O, where x can be between 0 and 0.3. 相似文献
17.
Cross sections for collision induced dissociation of 0.65 to 3.2 keV I+2(2Πg, υ) ions in I+2(2Πg, υ) + N2(X 1Σ+g, υ = 0) interactions have been determined. Reaction cross sections for I+2(2Π,g, υ) ions in low vibrational levels vary smoothly from 6 to 10 A2 with increasing kinetic energy. Dissociation cross sections for I+2(2Π,g, υ) ions are larger than those involving ground state ions. Processes involving highly excited metastable states of I+2 are not observed in this investigation. 相似文献
18.
Thermal-energy charge-transfer reactions from the 2P3/2 state of Ar+, Kr+ and Xe+ with NH3 are shown to be non-energy resonant: the kinetic energy released in each case has been measured, and the internal energy of the NH+3 product ions deduced. Possible quenching of 2P1/2 state of rare-gas ions in ICR cells is discussed. 相似文献
19.
Paul von Ragué Schleyer Yitzhak Apeloig Dorit Arad Brian T. Luke John A. Pople 《Chemical physics letters》1983,95(6):477-482
Differences between SiH+5 and CH+5 are more significant than the similarities. The proton affinity of SiH4 exceeds than of CH4 by ≈25 kcal/mol. but the heat of hydrogenation of SiH+3 is smaller than that of CH+3 by nearly the same amount. Like CH+5 the C5 structures of SiH+5 are preferred, but SiH+5 is best regarded as a weaker SiH+3—H2 complex. D3h, C2v, and C4v forms are much higher in energy and SiH+5 should not undergo hydrogen scrambling (pseudorotation) readily, as does CH+5 The neutral BH5 is only weakly bound toward loss H2, and the D3h. C2v, and C4v forms are also high in energy. The contral-atom electronegativities, C+ > B > Si+, control this behavior. The electronegativities also determine the ability to bear positive charges. Thermodynamically. SiH+5 and SiH+3 are more stable than CH+5 and CH+3, respectively; hydride transfer occurs from SiH4 to CH+3 and proton transfer from CH+5 to SiH4. 相似文献
20.
Some fragments of the NH+5 potential surface have been calculated by the SCF MO LCAO method using a basis of linear combinations of gaussian lobe functions. The NH+5 ion was found to be stable against dissociation into NH3 and H+2 or NH+3 and H2. Its stability with respect to decomposition into NH+4 and H remains to be seen. 相似文献