JCP Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

You Tube Flickr Twitter UniPHY Group iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

15 Dec 1973

Volume 59, Issue 12, pp. 6193-6691

Page 1 of 3 Pages Next Page | Jump to Page

Mechanism of CO fourth positive v u v chemiluminescence in the atomic oxygen reaction with acetylene. Production of C(3P, 1D)

Arthur Fontijn and Stanley E. Johnson

J. Chem. Phys. 59, 6193 (1973); http://dx.doi.org/10.1063/1.1679998 (8 pages) | Cited 19 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
CO(A 1Π−X 1Σ) emission from the O∕C2H2 reaction has been studied in a room temperature discharge flow system at pressures from 0.6 to 10 torr. Spectrometric measurements showed that CO(A 1Π) excitation extends to at least ν′ = 12, with anomalously large populations of the ν′ = 1, 4 and 6 levels. The overall emission intensity increases with increasing [Ar], [N2], and [He]. The presence of C(3P and 1D) atoms has been observed via resonance fluorescence. The probable CO(A 1Π)‐formation mechanism is O + C2O → CO* + CO, followed by collision‐induced cross relaxation: CO* + M → CO(A 1Π) + M, where CO* is identified as a CO state having a potential energy curve which overlaps that of CO(A 1Π), i.e., the d3Δ, e3Σ, a′3Σ and∕or D1Δ states. The hypothetical reaction C + O + M → CO(A 1Π) + M does not populate CO(A 1Π) to a significant degree.

Bound‐free transition of trapped electrons in polar matrices

Kenji Fueki, Da‐Fei Feng, and Larry Kevan

J. Chem. Phys. 59, 6201 (1973); http://dx.doi.org/10.1063/1.1679999 (8 pages) | Cited 4 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The photon energy dependence of the bound‐free transition probability for trapped electrons in polar matrices is calculated for ice, ethylene glycol‐water (50∕50), 2‐propanol, 2‐methyltetrahydrofuran, diisopropylamine, and triethylamine. A hydrogenic model is used for the transition probability, and the necessary parameters are calculated from a semicontinuum potential model. Both distorted wave and plane wave approximations are made. The calculated results are in reasonable agreement with the available experimental data on the photon energy dependence of photobleaching and photoconductivity efficiencies for trapped electrons in several matrices and support the assignment of bound‐free transitions to these processes. Distinct trends with matrix polarity are reproduced by the calculations.

Electronic structure and optical index damage of iron‐doped lithium niobate

M. G. Clark, F. J. DiSalvo, A. M. Glass, and G. E. Peterson

J. Chem. Phys. 59, 6209 (1973); http://dx.doi.org/10.1063/1.1680000 (11 pages) | Cited 105 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The properties of Fe2+, Fe3+, and other 3dn ionic impurities in the LiNbO3 structure are investigated with a view to elucidating the mechanism of laser‐induced reversible refractive index damage. Polarized optical absorption spectra of Fe2+ in LiNbO3 and LiTaO3 are reported and interpreted. The 2.66 eV band responsible for laser damage in Fe‐doped LiNbO3 is identified as Fe2+ → Nb5+ intervalence transfer. The Fe d ϵ level lies in the 3.7 eV band gap at about 0.6 eV below the conduction band, and the activation energy for thermal Fe2+ → Nb5+ electron transfer is estimated to be about 0.9 eV, in reasonable agreement with the value of 1.3 ± 0.2 eV observed for thermal bleaching of Fe2+ centers in x‐irradiated LiNbO3. Particular advantages of intervalence transfer as a mechanism for initiating optical index damage are noted. The observed electric field gradients in pure LiNbO3 and LiTaO3 are related to the B20 ligand‐field parameter of a 3dn (n ≠ 5) impurity ion. Comparison with experimental estimates of B20 may provide an indication of the site of the impurity ion, as in the case of Cr3+ which appears to favor the Nb∕Ta site. Magnetic susceptibility measurements in the range 4.2–300°K are reported for oxidized and reduced Fe‐doped LiNbO3. It is demonstrated that susceptibility studies may be used to estimate the concentrations of Fe2+ and Fe3+ in LiNbO3, and that in reduced LiNbO3 the Nb d ϵ electrons show Pauli paramagnetism characteristic of metallic behavior. It is argued that the system will be nonmetallic at the lower conduction electron concentrations encountered during optical damaging and bleaching of unreduced crystals, and that low electron mobility may be a significant factor in the thermal processes observed in optically damaged LiNbO3.

Ab initio studies of interoxygen bonding in O2, HO2, H2O2, O3, HO3, and H2O3

Richard J. Blint and Marshall D. Newton

J. Chem. Phys. 59, 6220 (1973); http://dx.doi.org/10.1063/1.1680001 (9 pages) | Cited 39 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The nature of the interoxygen bonding in O2, HO2, H2O2, O3, HO3, and H2O3 has been investigated on the basis of ab initio (LCAO‐MO) and experimental force constants, bond lengths, and energies. The fact that small basis sets appear to give the OO force constants for H2O2 and HO2 in the order opposite to that observed prompted an analysis of the sensitivity of the above properties with respect to various types of contracted Gaussian‐type orbitals (CGTOs). A large basis set of s and p CTGOs, [43∕2] is found to give proper qualitative account of OO bond lengths and force constants. However, polarization functions (3d functions on oxygen) are necessary for accurate calculation of relative bond energies in H2O2 and HO2. The species HO3 is estimated to be [inverted lazy s] 15 kcal∕mole unstable with respect to O2 + OH, in agreement with empirical estimates, thus making unlikely its potential role as a reaction intermediate. Hydrogen trioxide (H2O3) is calculated to have OO bonds slightly shorter ([inverted lazy s] 1.44 Å) than in H2O2 (1.48 Å), but with OO force constants similar in magnitude to H2O2, and a large OO stretching interaction force constant. The latter fact, in conjunction with spectral data from analogous systems, would be expected to make the symmetric stretch frequency in H2O3 larger than that for the antisymmetric mode, and this conclusion is discussed in the context of recent experimental data of Giguère et al., which is attributed to H2O3 and H2O4. The preferred anti conformation (C2 symmetry) of the OH bonds in H2O3 is noted as being potentially relevant to the conformation of intermediates in the ozonolysis of olefins. HO2 is calculated to have a very low lying (< 1 eV) excited state (2A′), as suggested by other workers, for which we estimate an OO bond length of 1.48 Å. Variations in OO bonding strength are analyzed in terms of Pauling bond orders and π‐electron density matrix elements. Force constants are not always found to vary monotonically with bond length, and the distinction between symmetrized and unsymmetrized force constants is emphasized in this connection.

F + H2, D2, HD reactions: Chemical laser determination of the product vibrational state populations and the F + HD intramolecular kinetic isotope effect

Michael J. Berry

J. Chem. Phys. 59, 6229 (1973); http://dx.doi.org/10.1063/1.1680002 (25 pages) | Cited 134 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Relative gain coefficients of individual HF†(DF†) laser transitions in the F + H2, D2, HD chemical lasers have been measured by a grating selection technique. Product vibrational population inversions Nν∕Nν−1 were calculated from these measurements. The results indicate a complete parallelism in product vibrational energy content in the four room‐temperature isotopic reactions, modified only by a threshold effect for HF†(ν = 3) production in the F + HD reaction and by secondary mass effects in the HF‐producing VS DF‐producing reactions. A room‐temperature measurement of the intramolecular kinetic isotope effect in the F + HD reaction is reported. Lastly, evidence is presented for highly efficient energy‐transfer processes [V → V′: HF†(ν = 3) + HD(ν = 0) → HF†(ν = 2) + HD†(ν = 1) and E → V: I*(5 2P1∕2) + HF†(ν) → I(5 2P3∕2) + HF†(ν + 2)].

Fully quantum study of near resonant D2‐D2 vibrational energy transfer

Millard H. Alexander

J. Chem. Phys. 59, 6254 (1973); http://dx.doi.org/10.1063/1.1680003 (12 pages) | Cited 36 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
We have carried out a detailed theoretical study of the 02–11 and 03–12 near‐resonant vibrational energy transfer processes which can occur during the collision of two D2 molecules. Assuming a collinear geometry, we have solved the collision dynamics fully quantum‐mechanically, using a modified version of the Gordon program. We have investigated three different model potentials and one full ab initio potential surface. Both at high and low collision energies, the V☒V transition probabilities are extremely sensitive to the particular potential surface used. We further show that nearest‐atom model potentials greatly overestimate transition probabilities at high energies. Also of interest is the result that at moderate to high energies near‐resonant V☒V transfer probabilities are largely insensitive to the choice of a harmonic or Morse oscillator description of the two colliding molecules. Finally we show that the simple two‐state approximation appears to be remarkably accurate over a wide range of energies.

Proton spin echo study of spin‐spin relaxation in liquid crystals

Ronald Y. Dong, M. Wiszniewska, E. Tomchuk, and E. Bock

J. Chem. Phys. 59, 6266 (1973); http://dx.doi.org/10.1063/1.1680004 (3 pages) | Cited 14 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Proton spin‐spin relaxation times ``T2'' were measured as a function of temperature in the nematic phase of p‐methoxybenzylidene‐p‐n‐butylaniline and in the nematic and smectic C phases of p‐n‐heptyloxyazobenzene using the 90°–45° echo. By comparing ``T2'' in these two liquid crystals, we infer that short range smectic order exists even 10° above the nematic‐smectic C phase transition in p‐n‐heptyloxyazobenzene. The angular dependence in ``T2'' was also determined in the smectic C phase at two different temperatures.

Overhauser effect on saturated lines of an AX spins system: 13C−1H in chloroform

J. C. Duplan, A. Briguet, and J. Delmau

J. Chem. Phys. 59, 6269 (1973); http://dx.doi.org/10.1063/1.1680005 (3 pages)

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
When saturating fields are successively applied at resonance frequencies of an AX spins system, the populations of the energy levels change towards new equilibrium values. The transient decay of a saturated line is used, in the case of chloroform, to obtain information about the relaxation of carbon‐13.

Thermal energy positive ion reactions in a wet atmosphere containing ammonia

F. C. Fehsenfeld and E. E. Ferguson

J. Chem. Phys. 59, 6272 (1973); http://dx.doi.org/10.1063/1.1680006 (5 pages) | Cited 30 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Rate constants for reactions of H+(H2O)n with NH3 for n = 1−4 have been measured at 296°K. Rate constants for NH4+ (H2O)1,2 with NH3 and the rate constant for NO2+(H2O) + NH3→NH4+ + HNO3 have also been measured. A number of equilibrium constants for reactions of the form NH4+(NH3)x(H2O)y + NH3⇄NH4+(NH3)x+1 (H2O)y−1+H2O have also been measured at 296°K. All of the measurements have been carried out in a flowing afterglow system.

Dissipative structures in chemical oscillations with concentrations‐dependent frequency

Marie‐Luce Smoes and Joseph Dreitlein

J. Chem. Phys. 59, 6277 (1973); http://dx.doi.org/10.1063/1.1680007 (9 pages) | Cited 14 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
A general model for the propagation of chemical waves is proposed for a given class of chemical oscillations. This model gives a satisfactory qualitative account of the dissipative structures observed in the Belousov‐Zhabotinskii reaction. The generality of this model makes it useful for predicting the possibility of chemical waves when the experimentally observed oscillations have a concentration‐dependent frequency.

Classical trajectory study of the K + CH3I reaction

R. A. LaBudde, P. J. Kuntz, R. B. Bernstein, and R. D. Levine

J. Chem. Phys. 59, 6286 (1973); http://dx.doi.org/10.1063/1.1680008 (13 pages) | Cited 42 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Classical trajectory calculations have been carried out in an attempt to simulate the reactive scattering of K by RI (R☒CH3). Several semiempirical three‐body potential surfaces have been explored. An electron‐jump surface of the covalent‐ionic type, with considerable ``repulsive energy release,'' accounts for most of the gross features of the scattering behavior. In particular, it has provided an understanding of the maximum in the reactive cross section σR (E) for the exchange reaction, which can be attributed to recrossing from the ionic to the covalent region of the potential. The present calculations also predict the onset (above 2.5 eV) of collision‐induced dissociation (CID), and show the conservation of total reaction cross section as CID takes over from the exchange reaction.

Classical trajectory study of exothermic ion‐molecule reactions

P. J. Kuntz and A. C. Roach

J. Chem. Phys. 59, 6299 (1973); http://dx.doi.org/10.1063/1.1680009 (13 pages) | Cited 18 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Classical trajectory studies of reactions A+ + BC → AB+ + C (BC = D2 or HD) over a wide range of collision energy E and on a number of exothermic potential energy surfaces show the dependence of the average translational exoergicity on reactant and product masses and on E to be nearly surface independent and of a form agreeing both with experiment for A = Ar and with the predictions of a number of direct interaction models. It is argued that this behavior may be a consequence of the relative lightness of BC and is not a sensitive indicator of the collision dynamics. Forward peaked angular distributions are observed on all surfaces at all energies, and at high energy a migration mechanism is demonstrated to contribute to the simultaneous occurrence of forward scattering and large momentum transfer to the product atom. There is no tendency for the product translational energy distribution to narrow at high energy, as would be expected if a stripping mechanism were approached.

Single crystal electron paramagnetic resonance study of tris (octamethylpyrophosphoramide) copper (II) perchlorate

Richard C. Koch, Melvin D. Joesten, and John H. Venable

J. Chem. Phys. 59, 6312 (1973); http://dx.doi.org/10.1063/1.1680010 (9 pages) | Cited 10 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Single crystal EPR spectra of tris(octamethylpyrophosphoramide) copper (II) perchlorate have been obtained at 90 °K. The results are correlated with x‐ray structural data and evidence is presented in support of a model in which three g tensors are related by the trigonal axis of the unit cell. The model is consistent with the dynamic‐static Jahn‐Teller theory proposed by Abragam and Pryce which assumes the presence of three mutually perpendicular tetragonal distortions of equal energy.

Primary processes of the photolysis of ethylenimine at Xe and Kr resonance lines

Masahiro Kawasaki, Masahiro Iwasaki, Toshio Ibuki, and Yoshimasa Takezaki

J. Chem. Phys. 59, 6321 (1973); http://dx.doi.org/10.1063/1.1680011 (7 pages) | Cited 6 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The direct and sensitized photolyses of ethylenimine vapor at Kr and Xe resonance lines have been studied. The hydrocarbon products are ethylene, ethane, methane, and small amounts of acetylene, propane, and n ‐butane. Other products detected are hydrogen, ammonia, and the dimers of ethylenimino radicals. The effect of added oxygen or ethylene has also been investigated. Emphasis being laid on the formations of methyl radicals, ethylene, and acetylene, the quantum yields of primary processes are determined as follows; (CH2)2NH + h ν → C2H4 + NH [I], CH3 + (H2CN) [II], and C2H2 + (NH3) [III]; at Xe resonance lines ϕI = 0.36, ϕII = 0.41, ϕIII = 0.028; at Kr resonance lines ϕI = 0.22, ϕII = 0.13, ϕIII = 0.028. Xe and Kr sensitized photolyses have also been studied. A very slight difference in the product distribution between the direct and sensitized photodecompositions has been observed.

Electronic states of imino radicals formed from the vacuum‐ultraviolet photolysis of ethylenimine

Masahiro Kawasaki, Masahiro Iwasaki, and Ikuzo Tanaka

J. Chem. Phys. 59, 6328 (1973); http://dx.doi.org/10.1063/1.1680012 (6 pages) | Cited 2 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The direct and sensitized photolyses of ehtylenimine (EI) vapor have been investigated at Kr and Xe resonance lines. The fluorescence of NH(c 1Π) or NH(A 3Π) resulting from the scission of EI is observed; EI + h ν(123.6 nm) → NH(c 1Π); EI + Kr*(3P1) → NH(c 1Π) and NH(A 3Π); EI + h ν(147.0 nm) → no emission; and EI + Xe*(3P1) → NH(A 3Π). It is suggested that the decomposition in the direct photolysis is in accordance with the spin conversation rule since NH(A 3Π) observed in the sensitized photolysis is not detected in the direct photolysis. In addition, an approximate application of the theory of unimolecular reaction to the decomposition of excited ethylene has been made in the direct photolysis of EI at Xe and Kr resonance lines indicating spin conservation in the direct photolysis, using the emiprical equation proposed by Hampson and McNesby.

Electron drift and Hall mobility in γ‐irradiated 10M NaOH glassy alkaline ice

T. Huang, I. Eisele, and L. Kevan

J. Chem. Phys. 59, 6334 (1973); http://dx.doi.org/10.1063/1.1680013 (16 pages) | Cited 7 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The drift and Hall mobility of electrons in 10M NaOH glassy alkaline ice has been studied to determine the relevant charge transport mechanisms in this disordered system. The electrons are photoexcited to a conduction state after being trapped in the matrix at 77 K by γ irradiation. The dominant electron scattering mechanisms have been deduced from variation of voltage and temperature, and it appears that electron transport in this matrix is well characterized by a band model. Field dependent mobilities are observed and indicate that hot electron effects exist. In the field independent mobility region, the limit of which depends on temperature, the dominant mechanism is scattering by acoustical and optical phonons. This holds above 77 K and probably to much lower temperatures. In the field dependent mobility region, the dominant mechanism is ionic species scattering, notably by O−, at lower temperatures, and acoustical and optical phonon scattering at higher temperatures. The dividing temperature decreases with increasing field and is ∼50 K at 4 kV cm−1. At constant temperature versus field, the mobility is dominated by phonon scattering in the field independent mobility region, by ionic species scattering in the initial part of the field dependent mobility region, and by phonon scattering again at high fields. Drift mobility, Hall mobility, and photoconductivity results all interrelate and give a consistent picture of electron transport in 10M NaOH. The super‐Ohmic photocurrents, previously observed, are seen to be due to dominance of ionic species scattering. The temperature and field dependence of the mobility is satisfactorily predicted by a simple band model and the mobility magnitude is at least semiquantitatively predicted. However, the critical field, at which hot electron effects occur, is predicted to be too high by the band model.

Vibrational deactivation rates of HF(ν = 1) by CH4, C2H6, C3H8, C4H10, C3H6, and ClF3

J. K. Hancock and W. H. Green

J. Chem. Phys. 59, 6350 (1973); http://dx.doi.org/10.1063/1.1680014 (8 pages) | Cited 16 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The rates at which vibrationally excited HF is deactivated by CH4, C2H6, C3H8, C4H10, C3H6, and ClF3 have been measured to be (5.3 ± 0.8) × 104; (1.10 ± 0.16) × 105; (1.35 ± 0.2) × 105; (1.7 ± 0.25) × 105; (3.2 ± 0.5) × 105 and (1.13 ± 0.17) × 105 sec−1 ⋅ torr−1, respectively, using the laser‐excited vibrational fluorescence technique. It was found that the cross‐section for HF deactivation by the lower alkanes, Cn H2n+2, varied linearly with n. The deactivation rate measured for HF☒ClF3 is orders of magnitude greater than has been observed for HF deactivation by other fluorine sources. The importance of the above rate measurements in the understanding and analysis of pulsed HF lasers is discussed in detail.

Thermodynamics of lithium‐isotope‐exchange reactions. IV. Exchange between the isotopic metals and solid fluorides

John C. Hall, Leonard F. Silvester, Gulzar Singh, and Peter A. Rock

J. Chem. Phys. 59, 6358 (1973); http://dx.doi.org/10.1063/1.1680015 (4 pages) | Cited 2 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
This paper reports our results for the direct experimental determination of the equilibrium constant for the lithium‐isotope‐exchange reaction 7Li(s) + 6LiF(s) = 6Li(s) + 7LiF(s). This reaction was studied in electrochemical double cells without liquid junction of the type 7Li(s)∣7LiF(s)∣KBF4(pc)∣6LiF(s)∣6Li(s), where pc represents the solvent propylene carbonate. The experimental value of the equilibrium constant for this reaction is K = 1.10 ± 0.01 (296°K). We also report here our results for a complete Born‐von Kármán lattice calculation of the equilibrium constant for the above reaction. The calculated result is K = 1.082 at 298.15°K. The above reaction exhibits the largest lithium isotope effect that has been found experimentally.

Electron spin polarized triplet state energy transfer in mixed organic single crystals at low temperatures

Henry C. Brenner

J. Chem. Phys. 59, 6362 (1973); http://dx.doi.org/10.1063/1.1680016 (18 pages) | Cited 10 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Transfer of photoexcitation from phenazine guest molecules to anthracene guest molecules in diphenyl single host crystals at 1.7°K, producing anthracene triplet species, was investigated by electron paramagnetic resonance methods. The triplet spin lattice relaxation rates were slow enough compared to depopulation rates so that preferential populating of the individual triplet sublevels of phenazine and anthracene could be observed. It was found that the long axis zero field state was populated fastest in both donor and acceptor, indicating that spin polarization was conserved in the transfer. This information was used along with several other experimental results to elucidate the nature of the processes responsible for the phenazine to anthracene transfer. It was concluded that the transfer took place either by means of a Dexter exchange process between triplet phenazine and unexcited anthracene, or by production of diphenyl triplet excitons from phenazine excited singlet species, and subsequent exciton migration and population of anthracene acceptor triplet traps. This latter route was suggested by the observation that singlet excitation of phenazine populated diphenyl‐h10 triplet traps in a mixed diphenyl‐d10∕h10 host crystal.

Dynamics of the O+☒H2 reaction. II. Reactive and nonreactive scattering of O+(4S3∕2) at relative energies above 13 eV

Keith T. Gillen, Bruce H. Mahan, and John S. Winn

J. Chem. Phys. 59, 6380 (1973); http://dx.doi.org/10.1063/1.1680017 (17 pages) | Cited 52 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
We report velocity vector distributions for the reactive and nonreactive scattering of O+ by H2, D2, and HD in the relative energy range 13–50 eV. Essentially no very small angle reactive scattering is observed for any of these systems. In the lower and intermediate parts of the energy range, the product of the O+(D2, D)OD+ reaction reaches a maximum intensity near 50°, and decreases somewhat at larger angles. This shape is maintained but with decreasing intensity from 15–30 eV relative energy. At higher energies, the distribution moves to larger angles and the intensity continues to drop. From 13–20 eV, OH+ from O+☒HD collisions peaks near 35°, and has little intensity at larger angles, while the corresponding OD+ product rises to a broad miximum near 90°, and is only slightly less intense at larger angles. At relative energies above 13 eV the nonreactive scattering of O+ has a major component that corresponds to the elastic impulsive scattering of O+ from one atom of the target. Nonreactive scattering from HD shows two peaks which correspond to impulsive O+☒H or O+☒D collisions. The experimental results are compared to the predictions of a model in which reaction occurs as the result of those sequences of two‐body hard sphere interactions which lead to bound product molecules. The general forms of the product angular distributions and their dependence on the isotopic composition of the target are fairly well represented by the model. For other features such as the experimental energy dependence of the total cross section (σ∝Erel−7/2) and the corresponding isotope effect, the model is less successful. A convenient velocity vector diagram method is given which allows a simple, edifying analysis of product angular distributions to be made with a compass and straightedge.

Infrared spectra of matrix‐isolated uranium oxide species. II. Spectral interpretation and structure of UO3

S. D. Gabelnick, G. T. Reedy, and M. G. Chasanov

J. Chem. Phys. 59, 6397 (1973); http://dx.doi.org/10.1063/1.1680018 (8 pages) | Cited 14 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The midinfrared spectra of matrix‐isolated UO3 and its oxygen‐18 isotopes have been successfully interpreted in terms of a C2ν T‐shaped structure. Values of the two bond‐stretching and two bond‐interaction force constants determined by a normal coordinate analysis using 13 observed frequencies reproduce all peaks in the observed spectrum to within ± 0.6 cm−1. The following assignments for U16O3 species trapped in argon matrices have been obtained: ν1(A1) = 843.50, ν2(A1) = 745.65, ν4(B1) = 852.60 cm−1. The structure and intensity distribution are discussed in terms of current bonding theory for uranyl compounds.

Determination of the proton affinity from the kinetics of proton transfer reactions. IV The equilibrium O2H++H2⇄H3++O2 and the relative proton affinity of O2 and H2

P. F. Fennelly, R. S. Hemsworth, H. I. Schiff, and D. K. Bohme

J. Chem. Phys. 59, 6405 (1973); http://dx.doi.org/10.1063/1.1680019 (7 pages) | Cited 15 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Equilibrium was established in both directions of the proton transfer reaction O2H++H2⇄H3++O2 proceeding in a flowing afterglow system. The equilibrium constant K was measured from equilibrium concentrations to be 1.05 ± 0.12 at 297°K. Limits to the rate constants were determined to be kforward ≥ 1.4 × 10−10 cm3 molecule−1 ⋅ sec−1 and kreverse ≥ 1.3 × 10−10 cm3 molecule−1 ⋅ sec−1. The value of K corresponds to a standard free energy change, ΔG2970, of −0.03+0.07−0.06 kcalmole−1 and leads to a proton affinity difference P A (O2) − P A (H2) = + 0.002 ± 0.003 eV.

An efficient numerical multicenter basis set for molecular orbital calculations: Application to FeCl4

F. W. Averill and D. E. Ellis

J. Chem. Phys. 59, 6412 (1973); http://dx.doi.org/10.1063/1.1680020 (7 pages) | Cited 211 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The use of numerical solutions to atomlike single site potentials as a basis for molecular orbital calculations is investigated. The atomic Hamiltonian is modified by addition of a potential well to induce additional discrete levels with the desired spatial characteristics. The discrete variational method is employed, in the Hartree‐Fock‐Slater model, to compare levels obtained for FeCl4 using multiple‐scattering, conventional Slater‐orbital, and numerical basis sets. The numerical technique is shown to be an accurate and efficient method for treating general (non‐muffin‐tin) molecular potentials. The errors in energy levels due to the muffin‐tin approximation are calculated.

Investigation of the ESR spectra of Cu2+ in K2Co(SO4)2 ⋅ 6H2O

B. A. Sastry and G. S. Sastry

J. Chem. Phys. 59, 6419 (1973); http://dx.doi.org/10.1063/1.1680021 (5 pages) | Cited 1 time

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
Electron spin resonance studies have been carried out on Cu2+ doped K2Co(SO4)2 ⋅ 6H2O at different temperatures. The resolution of the spectrum is found to be maximum at about 210 °K and the electric field symmetry around Cu2+ at this temperature is found to be rhombic having the spin‐Hamiltonian constants, gz = 2.330 ± 0.005, gx = 2.227 ± 0.005, gy = 2.053 ± 0.005, Az ≃ (60 ± 2) × 10−4 cm−1, Ax ≃ (52 ± 2) × 10−4 cm−1, and Ay ≃ (59 ± 2) × 10−4 cm−1. These spin‐Hamiltonian parameters are found to be temperature dependent. The linewidth of the copper hyperfine lines are found to increase with decreasing temperature which is most probably brought about by the superposition of a very broad Co2+ line on Cu2+ hyperfine line.

MC‐SCF. I. The multi‐configuration self‐consistent‐field method

Juergen Hinze

J. Chem. Phys. 59, 6424 (1973); http://dx.doi.org/10.1063/1.1680022 (9 pages) | Cited 194 times

Online Publication Date: 4 September 2003

Full Text: | Download PDF

Show Abstract
The general multi‐configuration self‐consistent‐field (MC‐SCF) method is presented with no restrictions on the types of configurations participating in the expansion of the total wavefunction. The general coupled Fock‐like equations for the ``best'' orbitals to be used in such a multi‐configuration wavefunction are derived. Formally these coupled nonlinear equations are decoupled with the use of projection operators and transformed into a pseudoeigenvalue problem. Several general methods, based on orbital transformations and on the use of the generalized Brillouin theorem, are presented for solving the coupled nonlinear Fock like equations for the determination of the MC‐SCF orbitals. The formalism presented is applicable not only to the ground state of a given system, but also to any excited state, yielding an upper bound to the true energy of the desired state.
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. Paramagnetic Moments for All Crystal Field Strengths of Octahedral Mn3+ Complexes
  2. Raman Band Shapes and Molecular Reorientation
  3. Self—Consistent Molecular Orbital Methods. XII. Further Extensions of Gaussian—Type Basis Sets for Use in Molecular Orbital Studies of Organic Molecules
  4. Water Cluster Formation Rates of NO+ in He, Ar, N2, and O2 at 296°K
  5. Moments of NMR Absorption Lines from the Free Induction Decay or Echo of Solids
Go to AIP Home
Copyright © American Institute of Physics
close