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AbstractAbstract

[en] Electron excitation cross sections to produce vibrationally excited H

_{2}molecules are calculated for molecules initially in the first and second vibrational levels. The pattern of excitation cross sections as a function of final vibrational level v'' differs from that found in previous calculations initiated from the ground vibrational levelPrimary Subject

Source

4. international symposium on the production and neutralization of negative ions and beams; Upton, NY (USA); 27-31 Oct 1986; CONF-8610115--

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AbstractAbstract

[en] The photodetachment cross section of a charged particle bound in a short range potential is an oscillating function of frequency of incident light, in the presence of a magnetic field. The theory of this effect is described, and calculated cross sections are shown. For photodetachment of electrons from negative atomic ions, this constitutes an additional magnetic field effect beyond the ones associated with fine and hyperfine structure of the ion and atom and with spin of the detached electron

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Source

4. international symposium on the production and neutralization of negative ions and beams; Upton, NY (USA); 27-31 Oct 1986; CONF-8610115--

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AbstractAbstract

[en] New measurements of inelastic proton scattering to low-lying states of /sup 208/Pb at 200 and 400 MeV are reported. Deformation lengths extracted from angular distributions for the 3

^{-}(2.614 MeV), 5^{-}_{1}(3.198 MeV), 5^{-}_{2}(3.209 MeV), 2^{+}(4.086 MeV) and 4^{+}(4.324 MeV) states are in good accord with values extracted at other incident proton energies. The fact that the deformation lengths are independent of incident proton energy within experimental uncertainty provides support for the validity of the collective DWBA for medium energy proton scattering to strongly excited states. Advantage is taken of this to extract statistically more precise values of the ratio of neutron to proton multipole matrix elements (M/sub n//M/sub p/). Different methods of determining the appropriate average value of M/sub n//M/sub p/ are discussedPrimary Subject

Source

2. conference on particle and nuclear physics; Lake Louise (Canada); 26-31 May 1986; CONF-860575--

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AbstractAbstract

[en] The results of recent large scale R-matrix calculations are used to study the convergence of the close coupling approximation for the calculation of electron excitation cross sections for atoms and ions. For the electron excitation of atoms these studies suggest that to obtain reliable cross sections below the ionization threshold it is necessary to include in the calculations a number of bound states which lie above the state under consideration. If the incident electron energy is just above the ionization threshold it is found that, even if we include a large number of bound states in the calculation, the cross section results do not converge to the true result and it is necessary to take account of continuum states in the close coupling expansion. However for the electron excitation of ions the convergence of the close coupling expansion is more rapid than that for atoms and the rate of convergence appears to increase as the nuclear charge of the ion increases

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16. international conference on the physics of electronic and atomic collisions; New York, NY (USA); 25 Jul - 1 Aug 1989; CONF-890708--

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Conference; Numerical Data

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AbstractAbstract

[en] A report is given on initial studies of neutron-deficient gold isotopes at the on-line isotope separator ISOLDE/CERN

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5. international conference on nuclei far from stability; Lake Rosseau (Canada); 14-19 Sep 1987; CONF-870970--

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AbstractAbstract

[en] The volume production of H

^{-}in Cs seeded discharge in H_{2}is discussed. The Kurchatov experiments^{1}reported such a high volume production. The mechanism responsible for the high current from a volume production source is considered to involve collisional energy transfer from excited Cs atoms in H_{2}vibrationsPrimary Subject

Source

4. international symposium on the production and neutralization of negative ions and beams; Upton, NY (USA); 27-31 Oct 1986; CONF-8610115--

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AbstractAbstract

[en] Ultracold collisions of neutral atoms can now be studied in the laboratory in the temperature range below 0.001 K. Rate coefficients for ultracold collisions of excited states are decreased by spontaneous emission during the long duration of the collision, but can be dramatically modified by intense laser effects on collision dynamics. Generalized MCQDT is used to develop criteria for the onset of quantum threshold behavior, which generally begins at temperatures above the Doppler cooling limit of light traps. Threshold Penning ionization of He metastable atoms in a light trap is predicted to occur with a rate coefficient larger than 5x10 (-11) cm

^{3}/secPrimary Subject

Source

16. international conference on the physics of electronic and atomic collisions; New York, NY (USA); 25 Jul - 1 Aug 1989; CONF-890708--

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AbstractAbstract

[en] The results of theoretical investigations of the excitation, quenching, ionization and broadening of the Rydberg atomic levels in inelastic collisions with ground-state atoms of buffer or parent gases are presented. The different physical mechanisms of these processes due to the scattering of the perturbing neutral particle on the quasifree electron and on the core of the Rydberg atom are considered. In particular the role of the potential and resonance scattering of the slow electron on the perturbing atoms in the quenching and broadening processes is discussed. The effects of the nonadiabatic transfer of the Rydberg electron energy to the kinetic energy of the colliding atoms and to the energy of the electronic shell of the quasimolecular ion are also considered. The results of calculations of the cross sections and the rate constants of the quenching, boradening and ionziation processes for some physcial systems are presented and are compared with available experimental data

Primary Subject

Source

16. international conference on the physics of electronic and atomic collisions; New York, NY (USA); 25 Jul - 1 Aug 1989; CONF-890708--

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Journal Article

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Conference; Numerical Data

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AbstractAbstract

[en] It has been proposed that electrical transport in boron carbides is accomplished by hopping of singlet electron pairs between bipolaronic states localized on the icosahedra. Formation of a bipolaron will be accompanied by a distortion of the associated icosahedron. We have used quantum-chemical calculational techniques to consider the relation between charge state and distortion for a system consisting of a B

_{12}icosahedron and 12 tieoff atoms. It is found that localization of two extra electrons on an icosahedron results in a contraction of the icosahedral cage and a reduction of the total energy of the cluster by approx.1.3 eV compared to that of the neutral cluster. The reduction in energy corresponds to the formation energy of a bipolaron in our model. Extensions of the model planned include calculations of polaron vs. bipolaron formation energiesPrimary Subject

Source

International conference on the physics and chemistry of boron and boron-rich borides; Albuquerque, NM (USA); 29-31 Jul 1985; CONF-850786--

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AbstractAbstract

[en] Detection of the Lyman alpha, Lyman beta and Balmer alpha photons and near-threshold energy loss electrons enables the determination of excited state lifetimes, total and differential excitation functions and various angular and polarization correlation parameters. Data are given for the summed n=2 and 3 states as well as the separate 2P, 3S, 3P and 3D states

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Conference; Numerical Data

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