共查询到20条相似文献,搜索用时 31 毫秒
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2.
K.K. Innes 《Journal of Molecular Spectroscopy》1983,99(2):294-301
Abnormally low frequencies observed for the out-of-plane vibration (b1) of the electronic state of formaldehyde (H2CO) and for the analogous carbonyl hydrogen vibration (a″) of propynal (HCCCHO) are modeled by means of two-state calculations of vibronic coupling with higher singlet states, 1B2 and 1A′, respectively. In each case, the active vibration is the out-of-plane hydrogen motion. The same vibronic calculations reproduce also the large positive anharmonicities of the active vibrations in the states; for H2CO the calculated vibrational spacing alternates as observed, consistent with the known nonplanar structure, while in propynal the calculated spacing increases regularly, thus predicting an effectively planar structure. The nonplanarity of H2CO is caused mainly by a vibronic coupling constant nearly twice that of propynal. The H2CO coupling constant is near the value estimated independently by means of the intensity “borrowed” by the S1-S0 transition from the much stronger S2-S0 transition. Brief consideration is given to analogous vibrational levels of the 1A2 state of H2CS and of the 3A2 state of D2CO in the vibronic context of this paper. 相似文献
3.
Harry Donald Brooke Jenkins Kenneth Frank Pratt 《Journal of Physics and Chemistry of Solids》1977,38(6):573-579
The opportunity to test a new equation for the computation of the lattice energy and at the same time examine a disparity in the literature data for the enthalpy of formation of the azide ion, was the motivation for this study. The results confirm our earlier calculation and show the new equation to be reliable. Thermodynamic data produced in the study take values: ΔHθhyd(N3?) = ?315 KJ mol?1 or ΔHθhyd(N3?) = ?295 KJ mol?1UPOT(NaN3) = 732 kJ mol?1UPOT(KN3) = 659 kJ mol?1UPOT(RbN3) = 637 kJ mol?1UPOT(CsN3) = 612 kJ mol?1UPOT(TIN3) = 689 kJ mol?1. The lattice energies of azides whose enthalpies of formation are documented have been calculated as well as the enthalpy of formation of the azide radical. 相似文献
4.
We suggest a simple definition of the topological charge density Q(x) in the lattice Yang-Mills theory and evaluate A≡∝d4x〈Q(x)Q(0)〉 in SU(2) by Monte Carlo simulation. The “data” interpolate well between the strong and weak coupling expansions, which we compute to order g?12 and g6, respectively. After subtraction of the perturbative tail, our points exhibit the expected asymptotic freedom behaviour giving , K being the SU(2) quarkless string tension. Although a larger value for would be preferable, we are led to conclude (at least tentatively) that the UA(1) problem of QCD is indeed solved perturbatively in the quark loop expansion. 相似文献
5.
The emission and excitation spectra of the aromatic thioketone xanthione have been measured in Shpolskii matrices at 15 K. Under these conditions a sharp and rich vibrational structure is observed in the lowest triplet and the first and second excited singlet states. The phosphorescence excitation spectrum places the origin of the T1 ← S0 transition at 15 143 cm?1, while that of the absorption is tentatively assigned to the band at 16 093 cm?1. The phosphorescence spectrum, which shows only a weak CS stretch vibrational band, is dominated by ring vibrations. In accordance with the previous analysis of ODMR measurements, it is suggested that T1 and T2 states are energetically very close, thereby resulting in a lowest triplet state of heavily mixed n, , character. No mirror-image relationship is found between the relatively strong S2 → S0 fluorescence and the excitation spectrum of the transition. The latter is dominated by a long, pronounced 336-cm?1 progression. 相似文献
6.
Richard Brower 《Nuclear Physics B》1981,190(4):699-718
In lattice gauge theory, many computations such as the strong coupling expansions, mean field theory, or the few plaquette models require the evaluation of the one-link integral in the presence of an arbitrary N × N complex matrix source (J). For SU(N) gauge theories, we express our general solution to the external field problem as an integral over the maximal abelian subgroup [U(1)]N?1 where S0 = 2Σkzk cos(φk ? θ), zj are eigenvalues of √JJ+, e2iNθ=detJ/detJ+, and G is an appropriate jacobian determinant. Our explicit solution follows from differential Schwinger-Dyson equations cast in a separable form by using fermionic variables, and the special cases of N = 2, 3 and ∞ agree with earlier derivations. 相似文献
7.
Jean-Paul Jurzak 《Reports on Mathematical Physics》1975,8(2):203-228
Let be a decomposable von Neumann algebra, ? a faithful strictly semi-finite weight on , σ?! the modular automorphism group associated with ?; if admits a cyclic and separating vector (or if π?()′ is countably decomposable, (π?, H?) being the representation of , given by ?), then we get (the ?ξ being faithful strictly semi-finite weights) and (σ?! is the modular automorphism group in (ξ), associated with ?).These results are obtained by developing the functional calculus for decomposable operators. More precisely, let be a Hermitian (bounded) decomposable operators, and f a complex essentially bounded function on R; then .Extensions of these results are given for nonessentially bounded measurable fields of bounded operators and for unbounded self-adjoint operators commuting with diagonalizable operators. 相似文献
8.
t-channel unitarity equations are derived for n-particle overlap functions. Together with s-channel unitarity they lead to scaling laws for the inelastic s-channel partial-wave amplitudes in the limits . Assuming the validity of the scaling law in the whole range, allowed by s-channel unitarity — i.e. for we obtain constant production cross sections σ(n)(s) at high energies s → ∞ up to s factors. 相似文献
9.
Excitation functions of the capture reaction 12C(p, γ0)13N have been obtained at θγ = 0° and 90° and Ep = 150–2500 keV. The results can be explained if a direct radiative capture process, E1(s and d → p), to the ground state in 13N is included in the analysis in addition to the two well-known resonances in this beam energy range and 1699 . The direct capture component is enhanced through interference effects with the two resonance amplitudes. From the observed direct capture cross section, a spectroscopic factor of C2S(l = 1) = 0.49 ± 0.15 has been deduced for the ground state in 13N. Excitation functions for the reaction have been obtained at θγ = 0° and 90° and Ep = 610–2700 keV. Away from the 1699 keV resonance the capture γ-ray yield is dominated by the direct capture process E1 (p → s) to the unbound state. Above Ep = 1 MeV, the observed excitation functions are well reproduced by the direct capture theory to unbound states (bremsstrahlung theory). Below Ep = 1 MeV, i.e., Ep → 457 keV, the theory diverges in contrast to observation. This discrepancy is well known in bremsstrahlung theory as the “infrared problem”. From the observed direct capture cross sections at , a spectroscopic factor of C2S(l = 0) = 1.02 ± 0.15 has been found for the unbound state. A search for direct capture transitions to the and unbound states resulted in upper limits of C2S(l = 1) ≦ 0.5 and C2S(l = 2) ? 1.0, respectively. The results are compared with available stripping data as well as shell-model calculations. The astrophysical aspect of the 12C(p, γ0)13N reaction also is discussed. 相似文献
10.
The deep inelastic structure function D(ω, q2) is calculated in the leading log approximation for . For larger ω up to ( the influence of reggeon cuts proves to slow down the growth of the structure function. A reggeon diagram technique is developed, and D is calculated up to a pre-exponent O(1), leading to D(ω, q2) ∝ q2 for . By assuming the reggeon diagrams when ω is still greater, one can expect to obtain a strong coupling behaviour: D(ω, q2) ∝ q2(ln ω)η (η <2). 相似文献
11.
Discharges through mixtures of helium and neon show two band groups near 4250 and 4100 Å as first observed by Druyvesteyn. These bands, assigned to the HeNe+ ion by Tanaka, Yoshino, and Freeman, have been studied under high resolution and have been fairly completely analyzed. The upper state of the transition is a very weakly bound state resulting from . There are two lower states resulting from the two components of . The upper of these two () is also very weakly bound while the lower of the two, the 2Σ+ ground state, has a dissociation energy of 0.69 eV and an re value of 1.30 Å. All bands in both band groups show four branches designated Rff, Qef, Qfe, and Pee. From their analysis the rotational constants in the various vibrational levels of the three electronic states have been determined. While no spin splitting in the B2Σ+ state has been found the ground state X2Σ shows a very large spin splitting and the state a very large doubling. The vibrational numberings in all these states were established by the study of the spectrum of 3HeNe+. At the same time the hyperfine structure observed in all lines of 3HeNe+ confirmed the nature of the upper state B2Σ+ as resulting from He+ + Ne, i.e., by charge exchange from the ground state. The component of the 2Π state has not been observed, presumably because of low intensity. 相似文献
12.
Comparison between experimental absorption due to the transition of substitutional Ni2+(d8) in GaP and theoretical predictions based on the Jahn-Teller model is presented. Numerical solution of the Hamiltonian, in which spin-orbit interaction and T2-mode Jahn-Teller coupling are included, is in very good agreement with the energy position and intensities of the observed absorption lines. 相似文献
13.
From the angular distributions of γ-rays emitted by oriented 129gTe and 129mTe nuclei implanted in iron by isotope separator, unique spin assignments could be made for the excited states of 129I at 487.4 keV , 696.0 keV , 729.6 keV , 768.9 keV , 1050.4 keV and 1111.8 keV . In addition, E2/M1 amplitude ratios for the following 129I γ-rays (energies are in keV) are derived: δ(459.6) = ?(0.076+0.037?0.148); δ(487.4) = 0.50+0.17?0.10 or δ? = 0.35+0.15?0.09; δ(556.7) = 0.06±0.02 or δ? = ?(0.10±0.02); δ(624.4) = 0.10±0.26 or δ? > 0.4; the 696.0 keV γ-ray is pure E2; δ(729.6) = ?(0.34±0.06) or δ?1 = 0.55±0.05; δ(741.1) = ?(0.27±0.10) or δ?1 = ?(0.43±0.12); δ(817.2) = 0.46±0.04 or δ?1 =0.20±0.03 if ; δ(1022.6) = ?(0.02 ±0.02) or δ?1 = ?(0.23±0.02); ; δ(1111.8) = 0.06±0.05 or δ?1 = ?(0.08±0.05). The anisotropy of the 531.8 keV γ-ray excludes as a possible spin assignment for the 559.6 keV level, so that no level is fed in the decay from 129Te. Anisotropies for the 209, 250.7, 278.4 and 281.1 keV γ-rays are also measured. Comparison of the level scheme is made with theoretical predictions from both the pairing-plus-quadrupole model and the intermediate coupling unified model. 相似文献
14.
Marek Danielewski Jaeosław Da̧bek Stanisł;aw Mrowec Grażyna Siemińska 《Solid State Ionics》1985,17(4):331-335
Using the re-equilibration kinetic method the chemical diffusion coefficient in nonstoichiometric chromium sesquisulfide, Cr2+yS3, has been determined as a function of temperature (1073–1373 K) and sulphur vapour pressure (10?104 Pa). It has been found that this coefficient is independent of sulphur pressure and can be described by the following empirical equation: . It has been shown that the mobility of the point defects inCr2+yS3 is independent of their concentration and that the self-diffusion coefficient of chromium in this sulfide has the following function of temperature and sulphur pressure: . (cm2s?1). 相似文献
15.
G. Mairle G.J. Wagner P. Grabmayr K.T. Knöpfle H. Riedesel K. Schindler V. Bechtold L. Friedrich P. Ziegler 《Nuclear Physics A》1982,382(2):173-184
The reactions have been investigated at Ed = 52 MeV. Vector analyzing powers as large as are observed. They exhibit patterns characteristic for final spins I = |L?1|, L or L + 1 and provide spin determinations at least for states of unique L-transfer. Local, zero-range DWBA calculations assuming deuteron-cluster pick-up reproduce qualitatively the observed effects. The method has been tested for states of known spin, and then has been applied to determine spins of states with stretched coupling in 16N: Jπ = 3+(3.96 MeV), 4?(6.17 MeV) and in 32P: Jπ = 5+(4.75 MeV). There is strong evidence for further 5+ states in 32P at 6.43, 7.96, 8.09 and 8.54 MeV. 相似文献
16.
Takashi Tonegawa 《Solid State Communications》1981,40(11):983-986
The transverse spin pair correlation function pxn=<SxmSxm+n>=<SxmSxm+n> is calculated exactly in the thermodynamic limit of the system described by the one-dimensional, isotropic, spin-, XY Hamiltonian . It is found that at absolute zero temperature (T = 0), the correlation function ρxn for n ≥ 0 is given by , , where the plus sign applies when J is positive and the minus sign applies when J is negative. From these the asymptotic behavior as n → ∞ of |?xn| at T = 0 is derived to be with a = 0.147088?. For finite temperatures, ρxn is calculated numerically. By using the results for ?xn, the transverse inverse correlation length and the wavenumber dependent transverse spin pair correlation function are also calculated exactly. 相似文献
17.
M. Djebara M. Asghar J.P. Bocquet R. Brissot M. Maurel H. Nifenecker CH. Ristori 《Nuclear Physics A》1984,425(1):120-140
A gas ΔE ? ER telescope has been used to measure charge yields and their correlations with kinetic energies for 229Th and 232U. Even-charge yields are enhanced compared with odd-charge yields for both fissioning systems; this enhancement increases for events with higher kinetic energy. The mean odd-even effect ; it is . The energy-integrated δp and δp for different energy windows, vary strongly as a function of charge (Z) due to the underlying shells. The δp averaged over Z increases fast with kinetic energy, contrary to the existing results for 233U and 235U, where δp flattens off at low energies. For both systems, the most probable kinetic energy ē shows a strong odd-even stagger; the mean odd-even effect on energy, the latter is about twice the value for . These results are discussed in terms of the existing models. 相似文献
18.
From the scaling law for the s-channel partial wave amplitudes, which guarantees simultaneously t-channel unitarity at threshold t = 4μ2 and s-channel unitarity, we derive: (i) The intercept α(0) of the Pomeron is always one, if α(4μ2) > 1. (ii) The total and the elastic cross sections are bounded from below for s → ∞. where α(4μ2) and δ(4μ2) are the position and the type of te Pomeron singularity (J ? α(4μ2))?1?δ(4μ2) at t = 4μ2. (iii) The type of the Pomeron singularity δ(4μ2) is restricted: either or . 相似文献
19.
Bernhard F. Gächter 《Journal of Molecular Spectroscopy》1976,63(1):1-22
The irreducible components of the Raman scattering tensor operator under the symmetry of a general point group are calculated. The unitary transformations U(ΓγΓksΓk′s′, ρσ) from the Cartesian and spherical components, respectively, to the irreducible components for the 32 crystallographic point groups are collected in tables. As an example the unitary transformation U(ΓγΓksΓk′s′, ρσ) is used to discuss the behavior of the scattering tensor in a resonance Raman experiment. With the help of the general formalism the scattering tensor for electronic Raman transitions of transition metal ions is calculated. As an example the scattering tensors of electronic Raman transitions within the 5T2 state of the high-spin trigonal distorted octahedral Fe2+ are calculated and the refinement of the selection rules is discussed. 相似文献
20.
The predictions of perturbative QCD are derived in the deep euclidean region, whereas the physical region for most observables is timelike. The confrontation of these predictions with experiment thus necessitates an analytic continuation. This we find introduces large higher order corrections in terms of αs(|Q2|), the usual choice ofperturbative expansion parameter. These corrections are naturally absorbed by changing to the expansion parameter , where αs(Q2)n is the leading term in the spacelike region. For the intermediate range of Q2 experimentally accessible at present, where is significantly smaller than αs(|Q2|), we find the resulting phenomenology is improved. In particular, we demonstrate how the values of obtained from analyses of quarkonium decays become consistent. 相似文献