Optical model theory of elastic electron- and positron-argon scattering at intermediate energies

Joachain, Charles; Vanderpoorten, R; Winters, Keith K.H.; Byron, F. W.

doi:10.1088/0022-3700/10/2/011

Cited by 78 publications

(17 citation statements)

References 26 publications

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“…The high-energy optical model calculations of Joachain et al. [40] (100 -500 eV, dashed curve C) and complex optical-potential results of Khare, Kumar, and Lata [43] (100 -800 eV, dashed curve B) compare reasonably well with the present and experimental data. Also shown in Fig.…”

Section: =0supporting

confidence: 83%

“…[43]; dashed curve C, optical model calculations of Ref. [40]); dashed curve D, optical potential results of Ref. [45].…”

Section: =0mentioning

confidence: 99%

“…The only intermediate-energy (1 -100 eV) calculations on the cr, for Ne and Ar systems are due to Bartschat, McEachran, and Stauffer [45,46], who employed an optical-potential method, quite similar to the present one except for the choice of optical potential; however, due to the neglect of ionization and Ps formation channels in the evaluation of optical potential, their o. , values are too low in comparison to the experimental data (see later). It is rather disappointing that very little 46 1279 K. L. BALUJA AND ASHOK JAIN 46 [2]; 4-19 [3]; 2-400 [4]; 4 Ep, - [5] 19-27 [7]; 16 -270 [9]; 50 -400 [10]; 2 -960 [12]; 2-18 [14] 0.3 -31 [ [20]; 0.35 -100 [21]; 1-6 [22]; 20-800 [24] none Theory 100 -3000 [37]; 100 -500 [38] 100 -700 [39]; 50 -1000 [41] 200-3000 [37]; 100-500 [38] 100-800 [42]; 1 -100 [46] 100-1000 [40]; 100 -800 [43] 3 -300 [44]; 1-100 [45] none none none attention has been paid theoretically to determine total cross section for positron-atom scattering at intermediate and high energies.…”

Section: Introductionmentioning

confidence: 99%

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Positron scattering from rare gases (He, Ne, Ar, Kr, Xe, and Rn): Total cross sections at intermediate and high energies

Baluja

1992

Phys. Rev. A

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The total (elastic plus inelastic) cross sections for positron scattering from all the rare gases are reported at intermediate and high energies (20-1000 eV), where experimental data are available for comparison except for the case of radon gas. A complex-optical-potential [ V,~, (ri] approach is employed in which the real part (static plus polarization terms) is calculated from Hartree-Fock or Dirac-Hartree-Fock target wave functions. The imaginary part of the optical potential, i.e. , the absorption potential [ V,b, (r}],is derived for each gas semiempirically from the corresponding electron absorption potential (r}] in the form of V+~, (r}= f (k, r}V, b, (r}, where f (k, r} depends on the incident energy (k') and radial distance (r). The V,b, is taken from the work of Truhlar and co-workers. The V,~, (r) is treated exactly in a partial-wave analysis under the variable-phase method. With the present form of V,~,(r), we are able to reproduce experimental 0, values at all energies considered here. An additional feature of the present results is that the inelastic cross sections compare very well with the measured inelastic (sum of positronium formation, excitation, and ionization cross sections) values for rare gases, where such experimental data are available. The 0. , for the positron-Rn system are predicted. We also discuss the correlation between scattering cross section and the atomic properties. We found that at intermediate and high energies, the positron-gas total cross section can be represented by an analytic formula o, (10 ' cm') =21. 16+aoia03}/EieV}, where ao is the target polarizability and E is the impact energy.This simple form of the o. , in terms of target polarizability works very well for highly polarizable targets such as the alkali-metal atoms and several hydrocarbon molecules. In particular, by using the above analytic formula for 0 "we have shown that our results for Na, K, Rb, C&H4, C,H6, and C3H6 targets compare very well with the experimental data. PACS number(s): 34.80.i, 34.90.+ q, 61.80.Fe

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Section: =0supporting

confidence: 83%

“…[43]; dashed curve C, optical model calculations of Ref. [40]); dashed curve D, optical potential results of Ref. [45].…”

Section: =0mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Positron scattering from rare gases (He, Ne, Ar, Kr, Xe, and Rn): Total cross sections at intermediate and high energies

Baluja

1992

Phys. Rev. A

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“…For example, Hyder et al have shown that their data at 100 eV and 200 eV are compatible with the polarized orbital calculations of McEachran and Stauffer (1986) and with a closely related "static + polarization" model potential calculation carried out by Nahar and Wadhera (1987). On the other hand; these data also agree with the second order optical model calculations of Joachain et al (1977) at these energies, as illustrated in Fig.3 for an incident energy of 100 eV. Now, as seen from the static, the polarization and the absorption potentials give markedly different results from those obtained either by using only the static potential (dotted line) or a "static + polarization" potential (dashed line).…”

Section: Elastic Scattering and Total Cross Sectionssupporting

confidence: 69%

Atomic Physics with Positrons

Humberston¹,

Armour²

1987

NATO ASI Series

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“…DCS for elastic electron scattering by argon atom at 100 eV impact energy. The data symbols used correspond to: (red circles) , Rankovic et al [49] experiment; (dark red full line), Rankovic et al [49] theory; (magenta solid line), McEachran and Stauffer [50]; (olive dash dot line), Paikeday and Alexander [51]; (dotted line), Nahar and Wadehra [52]; (violet dash dot dot line), Fon et al [53]; (cyan dash dot line), McCarthy et al [54]; (dashed line), Joachain et al [55]; (cyan up triangles), Milosavljević et al [56]; (violet left triangle), Panajotović et al [57]; (orange pentagons), Srivastava et al [58]; (blue diamond), DuBois and Rudd [59]; (orange right triangles), Jansen et al [60]; (green circles), Williams and Willis [61].…”

Section: Elastic Electron Scattering and Cross Sectionsmentioning

confidence: 99%

Rosetta Mission: Electron Scattering Cross Sections—Data Needs and Coverage in BEAMDB Database

Marinković

Bredehöft

Vujčić

et al. 2017

Atoms

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Abstract:The emission of [O I] lines in the coma of Comet 67P/Churyumov-Gerasimenko during the Rosetta mission have been explained by electron impact dissociation of water rather than the process of photodissociation. This is the direct evidence for the role of electron induced processing has been seen on such a body. Analysis of other emission features is handicapped by a lack of detailed knowledge of electron impact cross sections which highlights the need for a broad range of electron scattering data from the molecular systems detected on the comet. In this paper, we present an overview of the needs for electron scattering data relevant for the understanding of observations in coma, the tenuous atmosphere and on the surface of 67P/Churyumov-Gerasimenko during the Rosetta mission. The relevant observations for elucidating the role of electrons come from optical spectra, particle analysis using the ion and electron sensors and mass spectrometry measurements. To model these processes electron impact data should be collated and reviewed in an electron scattering database and an example is given in the BEAMD, which is a part of a larger consortium of Virtual Atomic and Molecular Data Centre-VAMDC.

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Optical model theory of elastic electron- and positron-argon scattering at intermediate energies

Cited by 78 publications

References 26 publications

Positron scattering from rare gases (He, Ne, Ar, Kr, Xe, and Rn): Total cross sections at intermediate and high energies

Positron scattering from rare gases (He, Ne, Ar, Kr, Xe, and Rn): Total cross sections at intermediate and high energies

Atomic Physics with Positrons

Rosetta Mission: Electron Scattering Cross Sections—Data Needs and Coverage in BEAMDB Database

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