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1.
The electronic spectra of the C3H? and C3D? anions have been studied above the lowest electron detachment threshold. On the basis of the vibrational, rotational analysis and ab initio calculations, the photodetachment spectrum is assigned to the d3 A″←a3 A″ Feshbach resonance in the bent chain C3H(D)? anion. The vibronic system is characterized by a long vibrational progression involving the CCH in plane bending mode ν4. The potential curves along this coordinate obtained from the spectral analysis and theoretical calculations reveal the importance of vibronic coupling in the electronic excited states. A strong Renner–Teller effect is thought to be the reason for the existence of the Feshbach resonance because the 4Σ? neutral parent and the 3Π anion excited states are close in energy. As for the neutral, ν4 appears to be the active mode and drives the interaction between the Feshbach and the dipole bound states.  相似文献   

2.
The most important aspects of the physics of the Ξ? ? atoms are reviewed in comparison with the other exotic atoms. The PANDA experiment will produce Ξ? ?’s hyperons using the intense beam of antiprotons provided by the future FAIR machine at GSI. The technique is briefly described and the feasibility of the Ξ? ?-atom production discussed. The preliminary estimates of the expected rates are reported.  相似文献   

3.
By the example of the lowest resonance state of the H? system, two versions of the stabilization method are considered: with introduction of an external potential into the Hamiltonian and with enlargement of the single-particle function basis. A comparison of the results suggests the possibility of applying these methods to calculating the resonance parameters in many-electron systems.  相似文献   

4.
A theoretical analysis of sub-Doppler molecular saturation spectroscopy by use of a confocal Fabry Perot (CFP) cavity is presented. The effects of gas pressure, cavity length and mirror reflectivity on the saturation dip amplitude are analysed. Such a treatment can provide the optimum conditions and a guidance for the experiment of saturating the weak molecular absorption lines.  相似文献   

5.
The molecular structures and spectroscopic constants of the ground electronic states of LiCl? and LiBr? are investigated with the coupled-cluster method. To improve the accuracy of our calculations, we have employed the extrapolation schemes as well as corrections of the core–valence correlation and scalar relativistic effect. The equilibrium parameters, potential energy curves, force constants, vibrational energy levels and spectroscopic parameters of both molecular ions are derived, in which those of LiBr? are reported for the first time. The electron affinities and vertical detachment energies of neutral and anionic LiCl and LiBr are also evaluated.  相似文献   

6.
A method for the theoretical study of chemical reaction mechanisms in aqueous solutions has been developed. Approximate reaction pathways are determined with the aid of a model Hamiltonian in which medium is described by a set of Langevin point dipoles. Solvation of stationary points on the potential energy surface so obtained is performed by a more exact calculation of the medium contribution using the method of minimization of the solvation shell potential energy. Usefulness of our approach is exemplified by the calculation of the reaction CO2 + OH ⇄ HCO3. Method MIND0/13 has been employed in constructing the model Hamiltonian. A good agreement with experiment has been achieved.  相似文献   

7.
The A3Π-X3Σ transition of NH has been observed using a high-resolution Fourier transform spectrometer. The first three vibrational levels in each state were observed and the vibrational, fine structure, and rotational constants obtained.  相似文献   

8.
S. Al-Rajoub 《哲学杂志》2015,95(22):2466-2481
The structural, electronic and optical properties of mercury cadmium telluride (Hg1?xCdxTe; x = 0.0, 0.25, 0.5, 0.75) alloys are studied using density functional theory within full-potential linearized augmented plane wave method. We used the local density approximation (LDA), generalized gradient approximation (GGA), hybrid potentials, the modified Becke–Johnson (LDA/GGA)-mjb and Hubbard-corrected functionals (GGA/LDA + U), for the exchange-correlation potential (Eex). We found that LDA functional predicts better lattice constants than GGA functional, whereas, both functionals fail to predict the correct electronic structure. However, the hybrid functionals were more successful. For the case of HgTe binary alloy, the GGA + U functional predicted a semi-metallic behaviour with an inverted band gap of ?0.539 eV, which is closest to the experimental value (?0.30 eV). Ternary alloys, however, are found to be semiconductors with direct band gaps. For the x = 0.25 and 0.50, the best band gaps are found to be 0.39 and 0.81 eV using LDA-mbj functional, whereas, the GGA-mbj functional predicted the best band gap of 1.09 eV for Hg0.25Cd0.75Te alloy, which is in a very good agreement with the experimental value (1.061 eV). The optical properties of the alloys are obtained by calculating the dielectric function ?(ω). The peaks of the optical dielectric functions are consistent with the electronic gap energies of the alloys.  相似文献   

9.
The excitation spectrum of BaO in the region above 32 000 cm−1 was investigated with a frequency-doubled pulsed dye laser. We have observed fully developed rotational structures of the C1Σ+-X1Σ+ transition. The analysis of the vibrational states v′ = 0 through 7 leads to a large number of perturbations. This spectroscopic information in combination with the observation and rotational analysis of transitions to several new electronic states allows a systematic summary, which gives more than eight electronic states in the investigated region. Besides the known states B, C, D and c, we find four new bound states, designated by E, F, G, and H. For all states molecular constants are given. The discussion of possible molecular electron configurations leads to classifications of the molecular electronic states. Our results on the vibrational levels v′ = 0 to 3 are in reasonable agreement to the optical-optical double resonance work of R. A. Gottscho, P. S. Weiss, and R. W. Field [J. Mol. Spectrosc. 82, 283–309 (1980)], but show several new details.  相似文献   

10.
We calculate theO s 2 ) correction to the energy-energy corelation cross section ine + e? annihilation using different resolution criteria in the limit of vanishing resolution cuts. We compare this in the back-to-back angular region with results of the logarithm approximation (LA) and deduce higher order corrections (beyondO s 2 )) from the LA formula. The final results are compared with recent TASSO data.  相似文献   

11.
The infrared spectra of CH2=CHF have been investigated in the ν5 and ν6 band regions between 1280 and 1400?cm?1, at a resolution of about 0.002?cm?1, using a tunable diode laser spectrometer. These vibrations of symmetry species A′ give rise to a/b-hybrid bands with different contributions from both the components. Spectral analysis resulted in the identification of 1565 (J≤46, K a ≤11) and 1651 (J≤48, K a ≤15) transitions of the ν5 and ν6 fundamentals, respectively. Both bands are perturbed by the nearby states ν8?+?ν9 and ν9?+?ν11 through different Coriolis resonances and an anharmonic interaction. Using Watson's A-reduction Hamiltonian in the Ir representation and perturbation operators almost all the transitions have been fitted simultaneously to a model including six resonances within the tetrad ν568?+?ν99?+?ν11. A set of spectroscopic constants for the ν5 and ν6 bands, as well as parameters for the dark states ν8?+?ν9 and ν9?+?ν11 and coupling constants, have been determined. From spectral simulations the dipole moment ratio |Δμ a /Δμ b | was estimated to be 0.6?±?0.1 and 2.0±0.3 for the ν5 and ν6 bands, respectively.  相似文献   

12.
ABSTRACT

We have recorded the a4Σ? 3/2 ? X1 2Π3/2 (0,0), (1,0), and (2,0) bands of gaseous gold monosulphide (AuS) at sub-Doppler resolution in the near-infrared region. The molecules were made in a hollow cathode discharge source by the reaction of sputtered gold with carbonyl sulphide. The high resolution of the laser excitation spectrum enabled the determination of molecular constants describing the rotational and 197Au hyperfine structure in both states, as well as the spin–rotation interaction in the a4Σ? 3/2 state. The natures of the two electronic states are discussed in the context of the observed hyperfine structure.  相似文献   

13.
14.
We report a joint photoelectron spectroscopic and theoretical study on the molecular anion, quinoline?. Analysis of the vibrationally resolved photoelectron spectrum found the adiabatic electron affinity, EAa(C9H7N), to be 0.16 ± 0.05 eV. These findings were supported by density functional theory calculations. Our experimental and computational results demonstrate the unusual electrophilicity for a polycyclic aromatic heterocycle.  相似文献   

15.
Baudelet  F.  Collin  G.  Dartyge  E.  Fontaine  A.  Kappler  J. P.  Krill  G.  Itie  J. P.  Jegoudez  J.  Maurer  M.  Monod  Ph.  Revcolevschi  A.  Tolentino  H.  Tourillon  G.  Verdaguer  M. 《Zeitschrift für Physik B Condensed Matter》1987,69(2-3):141-149
X-ray absorption spectroscopy has been used to probe the Cu environment of the new highT c YBa2Cu3O7– superconductor. Evidences of other valencies than two are found for copper. Besides Cu1+ which is localized on Cu1 sites when the unit cell is oxygendeficient, one invokes a ground state which merges bivalent 3d 9 to 3d 9 L configurations as proposed in a recent paper (L stands for a ligand hole in the CuO bond) very similar to that observed in many light rare earth oxides.  相似文献   

16.
This paper investigates the stereodynamics of the reaction He+HD+ by the quasi-classical trajectory(QCT) method using the most accurate AQUILANTI surface [Aquilanti et al 2000 Mol.Phys.98 1835].The distribution P(φr) of dihedral angle and the distribution P(θr) of angle between k and j have been presented at three different collision energies.Four generalized polarization-dependent differential cross-sections(2π/σ)(dσ00/dωt),(2π/σ)(dσ20/dωt),(2π/σ)(dσ22+/dωt),(2π/σ)(dσ21 /dωt) are also calculated.Some interesting results are obtained from the comparison of the stereodynamics of the title reaction at different collision energies.  相似文献   

17.
Ab initio X-ray absorption near edge structure (XANES) calculations for FeSexTe1−x, using a structural model that combines FeSe and FeTe phases at the nanoscale, are compared with Fe K-edge XANES measurements in the “pre-edge” region. The important aspects of this model are (i) magnetic order in the FeTe phase; (ii) Se and Te atoms placed randomly in both FeSe and FeTe crystallographic positions and; (iii) the two distinct distances for Fe–Se and Fe–Te of the bulk phases. The calculated spectra reproduce the observed increase of spectral weight in the experiments on FeSexTe1−x with Se concentration. This is consistent with an inhomogeneous local electronic structure of FeSexTe1−x. Additionally, we have calculated projected electronic density of d-states for the Fe atom, revealing increased spectral weight in the “pre-edge” region of the XANES spectra, which correlates with the increase in Se concentration. The decrease of calculated Fe d-density of states for the Fermi level, N(εF), for high Te content is consistent with the suppression of superconductivity in the title system.  相似文献   

18.
Theoretical Analysis of the Exotic Structure of ^17F   总被引:1,自引:0,他引:1       下载免费PDF全文
The first excited state and the ground state of ^17F are studied with the asymptotic normalization coefficient method. The results show that the probabilities of the last proton being out of the binding-potential in both the states are P = 59.71% and P = 27.61%, respectively. This means that the last nucleon in both the states of ^17F is far-extended beyond the range of nuclear force, especially in the first excited state. This result is also verified by the calculation of the density distributions of the last proton in ^17F. It is quantitatively confirmed that the first excited state of^1TF is a nuclear halo state and its ground state is a proton skin state.  相似文献   

19.
The spectrum of H2 18O in the range 15000–15700 cm?1 has been recorded for the first time on a Fourier-transform spectrometer using a high-brightness light-emitting diode as a radiation source. The measurements have been conducted at room temperature with a resolution of 0.05 cm?1. A threshold sensitivity in absorption of 2 × 10?7 cm?1 has been achieved due to both the use of a light-emitting diode and optimization of the multipass cell with a base length of 60 cm, which ensured a 19.2-m length of the absorbing layer. A high signal-to-noise ratio (S/N = 2000–10000) made it possible to record about 670 water-vapor lines with intensities of 1.0 × 10?26–2.2 × 10–24 cm/mol at 296 K. The energies of 265 vibrational-rotational levels of the H2 18O molecule are determined and attributed to seven vibrational states, namely, (033), (113), (212), (231), (311), (330), and (410).  相似文献   

20.
Fourier transform spectra have been recorded for carbon disulphide (CS2) in the region between 3400 cm?1 and 4400 cm?1. A data analysis has determined new molecular constants: 14 bands were observed for the main isotopic form 12C32S2, two bands for the isotopomer 12C32S34S and one each for 12C32S33S and 13C32S2.  相似文献   

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