Elastic collisions of low- to intermediate-energy electrons from carbon dioxide: Experimental and theoretical differential cross sections

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Absolute differential cross sections (DCSs) for electron interaction with BF 3 molecules have been measured in the impact energy range of 1.5-200 eV and recorded over a scattering angle range of 15 • -150 • . These angular distributions have been normalized by reference to the elastic DCSs of the He atom and integrated by employing a modified phase shift analysis procedure to generate integral cross sections (ICSs) and momentum transfer cross sections (MTCSs). The calculations of DCSs and ICSs have been carried out using an independent atom model under the screening corrected additivity rule (IAM-SCAR). The present elastic DCSs have been found to agree well with the results of IAM-SCAR calculation above 20 eV, and also with a recent Schwinger multichannel calculation below 30 eV. Furthermore, in the comparison with the XF 3 (X = B, C, N, and CH) molecules, the elastic DCSs reveal a similar angular distribution which are approximately equal in magnitude from 30 to 200 eV. This feature suggests that the elastic scattering is dominated virtually by the 3-outer fluorine atoms surrounding the XF 3 molecules. The vibrational DCSs have also been obtained in the energy range of 1.5-15 eV and vibrational analysis based on the angular correlation theory has been carried out to explain the nature of the shape resonances. Limited experiments on vibrational inelastic scattering confirmed the existence of a shape resonance with a peak at 3.8 eV, which is also observed in the vibrational ICS. Finally, the estimated elastic ICSs, MTCSs, as well as total cross sections are compared with the previous cross section data available. C 2015 AIP Publishing LLC. [http://dx

Section: Methodsmentioning

confidence: 99%

Crossed-beam experiment for the scattering of low- and intermediate-energy electrons from BF3: A comparative study with XF3 (X = C, N, and CH) molecules

Hoshino

Limão‐Vieira

Suga

et al. 2015

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“…The present experiments were performed with two electron spectrometers that have been described in detail in previous papers (e.g., Tanaka et al 49 and Kato et al 46 ). Briefly, in both systems, the main features are a crossed electronmolecular beam arrangement, incorporating hemispherical monochromators and analyzers, electron lens systems with computer-driven voltages, and differential pumping for the electron optics.…”

Section: Methodsmentioning

confidence: 99%

A comprehensive and comparative study of elastic electron scattering from OCS and CS2 in the energy region from 1.2 to 200 eV

Murai

Ishijima

Mitsumura

et al. 2013

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We report absolute differential cross sections (DCSs) for elastic electron scattering from OCS (carbonyl sulphide) and CS 2 (carbon disulphide) in the impact energy range of 1.2-200 eV and for scattering angles from 10 • to 150 • . Above 10 eV, the angular distributions are found to agree quite well with our present calculations using two semi-phenomenological theoretical approaches. One employs the independent-atom model with the screening-corrected additivity rule (IAM-SCAR), while the other uses the continuum-multiple-scattering method in conjunction with a parameterfree exchange-polarization approximation. Since OCS is a polar molecule, further dipole-induced rotational excitation cross sections have been calculated in the framework of the first Born approximation and incoherently added to the IAM-SCAR results. In comparison with the calculated DCS for the S atom, atomic-like behavior for the angular distributions in both the OCS and CS 2 scattering systems is observed. Integrated elastic cross sections are obtained by extrapolating the experimental measurements, with the aid of the theoretical calculations, for those scattering angles below 10 • and above 150 • . These values are then compared with the available total cross sections.

“…The new spectrometer is configured in a classic crossed-beam geometry 25 and consists of an electron gun with hemispherical monochromator, an effusive molecular beam source ͑single capillary of length 6.5 mm and inner diameter 0.5 mm͒, and a rotatable scattered electron detector ͑angular range= −10°to 150°͒ with a second hemispherical analyzer system and a channel electron multiplier detector. Both the electron source and electron analyzer contain a number of aperture-type electron optic elements, which transport and focus the incident and scattered electrons.…”

Section: Methodsmentioning

confidence: 99%

Substitution effects in elastic electron collisions with CH3X (X=F, Cl, Br, I) molecules

Kato

Asahina

Masui

et al. 2010

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We report absolute elastic differential, integral, and momentum transfer cross sections for electron interactions with the series of molecules CH 3 X ͑X = F, Cl, Br, I͒. The incident electron energy range is 50-200 eV, while the scattered electron angular range for the differential measurements is 15°-150°. In all cases the absolute scale of the differential cross sections was set using the relative flow method with helium as the reference species. Substitution effects on these cross sections, as we progress along the halomethane series CH 3 F, CH 3 Cl, CH 3 Br, and CH 3 I, are investigated as a part of this study. In addition, atomic-like behavior in these scattering systems is also considered by comparing these halomethane elastic cross sections to results from other workers for the corresponding noble gases Ne, Ar, Kr, and Xe, respectively. Finally we report results for calculations of elastic differential and integral cross sections for electrons scattering from each of the CH 3 X species, within an optical potential method and assuming a screened corrected independent atom representation. The level of agreement between these calculations and our measurements was found to be quite remarkable in each case.