摘要:

We present electron energy spectra arising from the reaction of thermal metastable Helium atoms He(23S) with Br2and I2. In addition we have used an electron-ion-coincidence technique to isolate the spectra of those electrons which are coincident with the parent ions Br+2and I+2. To our knowledge these spectra have not been published before. In addition to the experiments we have performed trajectory calculations on a model potential surface in order to gain insight into the collision complex. The goal was to determine the shape of the model potential by comparing calculated and experimental electron spectra. This work is part of a project on transition state spectroscopy of autoionizing collision complexes.

ISSN:0026-8976    

DOI:10.1080/00268978600101101

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The rate of electron transfer in polar media is calculated in the framework of the transition state theory. It is shown that this theory is valid ifkBT> (hω0/2π), where ω0is the frequency of a particle motion at the barrier top. The pre-exponential factor of the rate constant is found to be dependent on the reaction heat, dielectric loss spectrum, ϵ(ω), and the nondiagonal matrix element, Г. The rate constant of charge transfer in water, with allowance for the resonance absorbtion region, is determined. The influence of the motion of the water complexes on the rate constant is considered and it is shown that the pre-exponential factor depends not only on the frequency of the complex vibrations, but also on its reorganization energy. The maximum value of the complex reorganization energy is calculated under the conditions where the theory is valid. In the particular case of the Debye dielectric loss spectrum the multidimensional activated complex theory is shown to be equivalent to the stochastic Alexandrov-Zusman's model and the Kramers' theory (the case of large viscosity). It is pointed out that the transition state theory allows the inertial degrees of freedom to be taken into account for a real dielectric loss spectrum, ϵ(ω).

ISSN:0026-8976    

DOI:10.1080/00268978600101111

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Rare gas collision-induced far infrared absorption spectra have been simulated classically at three reduced temperatures,T* = 4, 2, 1. At the lowest temperature (T* = 1), bound states make a significant contribution (20 per cent). The results are compared to an asymptotic theory of the line shape. The agreement is perfect in the wings of the line, as expected, but is also surprisingly good at lower frequencies.

ISSN:0026-8976    

DOI:10.1080/00268978600101121

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A quantitative analysis of microwave induced optical nuclear polarization is given for the system fluorene doped with phenanthrene. The description is based on the solid effect theory and includes the effect of holeburning in the inhomogeneously broadened E.S.R. line.

ISSN:0026-8976    

DOI:10.1080/00268978600101131

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The static polarizabilities of the ground state of N2were calculated at three different internuclear separations in the LCAO-SCF-MO approximation. All independent components of electric polarizability tensors up to the fourth rank were included. The isotropy and anisotropy of the γ tensor are γ = 766, Δ1γ = 2264 and Δ2γ = -76e4a40E-3hrespectively (at the experimental internuclear separation of 2·0744a0).

ISSN:0026-8976    

DOI:10.1080/00268978600101141

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Semiempirical valence bond calculations based on a modified LEPS method which have been reported previously for the potential energy surfaces of the homonuclear alkali trimers are now extended to theM′M2systems (M′,M= Li through Cs). The force constants and vibrational frequencies to stretching and bending of the optimalC2vstructures for the trimers have been calculated, and the geometries of such structures rationalized on the basis of Walsh-type diagrams. With basis on the simple molecular orbital theory, it is predicted that the ESR spectra of theM′M2trimers may show dramatic differences depending on whether the two equal atoms are heavy (i.e., LHH or type I) or light (HLL; type II). However, for all members of a given type, the ESR are predicted to be similar, irrespectively of the specific atoms involved.

ISSN:0026-8976    

DOI:10.1080/00268978600101151

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Neutron and X-ray diffraction measurements of liquid sulphuric acid are reported. The aim of the present work is to study the arrangement of the hydrogen atoms in the liquid in comparison with the solid phase. By employing both experimental techniques, the localization of both heavy atoms and hydrogen is possible. We find that the sulphuric acid liquid-structure closely resembles the corresponding solid, although it appears that no connection exists between the structure of a hydrogen bonded liquid and the state of order of the hydrogen atoms in the solid phase.

ISSN:0026-8976    

DOI:10.1080/00268978600101161

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The probability density for changes in direction of molecular motion was investigated as a function of time in simulations of CF4and CS2near their triple points. The probability of forward and reversed motion shows features related to the shape of the velocity correlation function. These features are enhanced in a group of molecules chosen with high initial kinetic energies. This and other observations lead to the suggestion that the motion of high energy molecules is primarily a rattling within the cage of nearest neighbours, while low energy molecules move in a diffusional way. The life time of the cage defined by the nearest neighbours is long compared to the velocity correlation times.

ISSN:0026-8976    

DOI:10.1080/00268978600101171

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Intense luminescence due to the2F5/2→2F7/2transition, near 1μm, is observed when the elpasolites Cs2NaHoCl6and Cs2NaNdCl6are doped with Yb3+and excited by 488 nm or 514 nm argon ion laser radiation respectively. The mechanism of energy transfer has been studied for Cs2NaHoCl6: YbCl3-6using temperature, concentration and kinetic studies, and involves a cross-relaxation from5F5(HoCl3-6). The liquid-helium-temperature luminescence spectra are interpreted, and together with the absorption spectrum of Cs2NaYbCi6all of thef13energy levels are assigned. The agreement with the latest crystal field calculations is poor. A comparison is made with the luminescence and excitation spectra of Cs2NaHoBr6: YbBr3-6. No luminescence from YbCl3-6at a site of octahedral symmetry is observed in Yb3+-doped Cs2NaTmCl6or Cs2NaErCl6. In the former case the closest level is about eight phonons above2F5/2so that the Yb3+level is not appreciably populated, and in the latter case the4I11/2(ErCl3-6) levels are located just below, and hence depopulate2F5/2.

ISSN:0026-8976    

DOI:10.1080/00268978600101181

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The photoelectron spectrum of methyl anion was simulated by invoking a potential function ofV(q) =q2/2 + σRq4for methyl radical with σR= 0·085 and a double-minimum potentialV(q) =q2/2 + σAq4+ κ exp (-ζq4) with σA= 0·005, κ = 16·629 and ζ = 0·050 by considering the out-of-plane vibration (ν2) alone. The agreement between the theoretical and the experimental spectra is excellent. From the intensity calculation, the bond angle and the inversion barrier of the anion are found to be respectively 108· ± 1·4° and 705 ± 40 cm-1in comparison with values of 110° and 620 to 680 cm-1from anab initiocalculation [11]. From another Franck-Condon factor calculation, the bond length of CH-3is estimated to be close to that of CH3probably within 0·025 Å.

ISSN:0026-8976    

DOI:10.1080/00268978600101191

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor