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  • 1
    Electronic Resource
    Electronic Resource
    Low energy electron scattering in CF2Cl2 and CF3Cl (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 3045-3052 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Experimental data are presented for the scattering of electrons by CF2Cl2 and CF3Cl for both integral and backward scattering, from 2 eV (for CF2Cl2) and 0.65 eV (for CF3Cl) down to energies of 10 meV to 20 meV, with an energy resolution ranging from 0.75 meV to 1.5 meV (full width at half maximum) in the electron beam. Both molecules have dipole moments of ∼0.5 D and are expected to show very similar rotationally inelastic scattering cross sections. Cross sections for CF2Cl2 are, however, much larger at low energy than for CF3Cl, attributed to short-lived attachment of electrons to CF2Cl2. CF3Cl displays powerful suppression of rotational excitation in the forward direction, most strongly around 70 meV impact energy. This is ascribed to interference between a direct channel of rotational excitation and indirect excitation via a short-lived negative ion state. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1387475
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  • 2
    Electronic Resource
    Electronic Resource
    An X-ray diffraction study of lithium (1982)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 38 (1982), S. 163-165 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: An accurate X-ray diffraction investigation has been carried out on two single crystals of lithium. The data from crystal 1 were obtained at temperatures of 248 and 296 K, and those for crystal 2 in the temperature range 293 to 423 K. The measured integrated intensities have been analysed for the presence of anharmonicity in the atomic vibrations by using a temperature factor based on a one-particle potential of the form V(u) = ½ αu2 + γu4 + δ(u4x + uy4 + uz4 - u4). An average value for the parameter δ of 290 ± 140 eV nm-4 was found. No significant value of γ was found in the analysis of data from crystal 1, but a value of -360 ± 40 eV nm-4 was obtained from the higher-temperature data of crystal 2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739482000291
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  • 3
    Electronic Resource
    Electronic Resource
    The temperature dependence of the integrated X-ray diffracted intensities from sodium metal (1976)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 32 (1976), S. 315-319 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The temperature dependence of the integrated X-ray diffracted intensities in sodium metal has been determined for the 222, 400, 330, 411 and 332 reflexions in the temperature range 148 K to the melting point of 371 K. In the temperature range 148 K to about 300 K, all the data can be fitted using a quasi-harmonic approximation for the temperature factor. From room temperature to the melting point the intensities for all the reflexions were observed to decrease rapidly with temperature, and could not be fitted either with a quasi-harmonic or fourth-order anharmonic model for the temperature factor. There is no evidence for anisotropy in the intensities below room temperature, but from 293 K to the melting point, anisotropy increases rapidly. A qualitative explanation of the high-temperature phenomena in terms of a lattice relaxation around the vacancies has been advanced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739476000697
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  • 4
    Electronic Resource
    Electronic Resource
    An X-ray study of thermal vibrations in sodium (1974)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 30 (1974), S. 234-238 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A room-temperature X-ray study of Bragg reflexions from sodium metal crystals has been made. Six sets of integrated relative intensities were recorded photographically from two single crystals. Considerable anisotropy in the intensities has been found and it is suggested that this is due to anharmonic vibrations of the atoms. The data has been analysed in terms of a fourth-order atomic-potential expansion and values of an isotropic Debye parameter and an anharmonic anisotropic vibration parameter are given. The observed values of the available structure factors are presented. The accuracy claimed is 2%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739474000489
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  • 5
    Electronic Resource
    Electronic Resource
    An X-ray diffraction study of potassium (1982)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 38 (1982), S. 3-10 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Accurate relative and absolute integrated intensities have been measured in an X-ray diffraction experiment on two single crystals of potassium in the temperature range 207 to 337 K. In order to examine the possible significance of anharmonic contributions to the atomic vibrations and the temperature factor, the data were analysed with a fourth-order anharmonic one-particle potential of the form V (u) = ½αu2 + γu4 + δ(u4x + u4y + u4z -- u4). The isotropic parameter γ and the anisotropic parameter δ were both found to be significant, with respective values averaged from the data from the two crystals of -45 ± 5 eV nm-4 and + 41 ± 5 eV nm-4. The positive sign of δ indicates that there is a greater probability of vibration of the atoms in the nearest-neighbour directions than the next- nearest-neighbour directions. A possible explanation for this in terms of rapid migration of lattice vacancies is suggested. The average value of the harmonic parameter a at 293 K was 15.1 ± 0.3 eV nm-2, from which the root-mean-square vibration amplitude was determined as ur.m.s. = 0.0741 ± 0.0012 nm at 293 K, and the Debye temperature was determined as 81 ± 1 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739482000023
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  • 6
    Electronic Resource
    Electronic Resource
    On anharmonicity in cadmium (1982)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 38 (1982), S. 10-12 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Recent X-ray diffraction data on cadmium [Rossmanith (1978). Acta Cryst. A34, 497-500] have been reanalysed using a temperature factor based on an anharmonic one-particle potential to fourth order for the atoms, and values for the anharmonic parameters have been obtained. The fourth-order parameters α40 and β20 are found not to be significantly different from zero, while the other fourth-order parameter γ00 is found to be strongly correlated to the extinction correction and harmonic parameters. The third-order antisymmetric parameter is found to have a value of 57 ± 16 eV nm-3, which is in reasonable agreement with a recent measurement. The application of the extinction correction is shown to affect substantially the values for the potential parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739482000035
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  • 7
    Electronic Resource
    Electronic Resource
    Collisions of OH and other orbitally degenerate molecules: a consistent treatment of the azimuthal dependence of the interaction potential
    Amsterdam : Elsevier
    Journal of Electroanalytical Chemistry 122 (1985), S. 310-314 
    Details
    ISSN: 0368-1874
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0368-1874(85)80034-4
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  • 8
    Electronic Resource
    Electronic Resource
    Collisions of OH and other orbitally degenerate molecules: A consistent treatment of the azimuthal dependence of the interaction potential
    Amsterdam : Elsevier
    Chemical Physics Letters 122 (1985), S. 310-314 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(85)80227-X
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  • 9
    Electronic Resource
    Electronic Resource
    Dye laser spectroscopy of BO"2: fermi resonance between the 100 and 020 levels of the ^2Ii"g ground state
    Amsterdam : Elsevier
    Chemical Physics Letters 50 (1977), S. 1-5 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(77)80667-2
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  • 10
    Electronic Resource
    Electronic Resource
    Monte Carlo simulations of electron distributions in the sheath region of reactive-ion-etching plasmas (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 1634-1643 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of a Monte Carlo model for calculating the trajectories of electrons in the plasma sheath region in reactive-ion-etching plasmas are described. The calculations illustrate how the oscillating movement of the sheath imparts energy to electrons and alters the electron energy distribution (EED) within the bulk of a 13.56 MHz Ar discharge. The study is limited to low-pressure discharges of less than about 10 mTorr, where the effects of electron-molecule collisions can be ignored. Under these conditions it is found that the sheath imparts energy preferentially to low-energy electrons. Calculated EEDs for electrons striking the electrodes in a radio-frequency reactor are also presented. Most electrons strike the electrodes with energies of a few eV, but some electrons strike the substrate surface with impact energies as high as 20 eV. This may be an important consideration when modeling etch mechanisms. Secondary electron emission caused by ion bombardment of the electrodes is also modeled. Simulated EEDs for secondary electrons that are produced at the electrodes and accelerated by the action of the sheath potential into the plasma region are presented. These electrons have energies of up to several hundred eV and are therefore important in plasma-sustaining mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353197
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