Positron scattering from methane

Zecca, Antonio; Chiari, Luca; Trainotti, Emanuele; Sarkar, A.; Sanchez, S. d’A.; Bettega, M. H. F.; Varella, Márcio T. do N.; Lima, Marco A. P.; Brunger, M. J.

doi:10.1103/physreva.85.012707

Cited by 35 publications

(47 citation statements)

References 38 publications

(103 reference statements)

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“…The behavior of our measured and computed cross sections at very low energy is consistent with the presence of a virtual state, as was seen in [4]. We show in Fig.…”

Section: Resultssupporting

confidence: 69%

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Positron collisions with ethene

et al. 2012

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“…The behavior of our measured and computed cross sections at very low energy is consistent with the presence of a virtual state, as was seen in [4]. We show in Fig.…”

Section: Resultssupporting

confidence: 69%

“…However, agreement among theoretical and experimental data obtained by different groups is still not particularly satisfactory, even for the total cross section (TCS) of simple targets [2][3][4]. Further improvements in scattering models and experimental techniques would thus be desirable.…”

Section: Introductionmentioning

confidence: 99%

Positron collisions with ethene

et al. 2012

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“…4) different experimental data strongly disagree. Note that Zecca's results [74] were obtained on a modified Trento apparatus when compared to earlier experiments in Ar and N 2 by Karwasz et al [13]. This modified system was composed of a shorter scattering cell (2.21 cm as compared to earlier 10 cm) and a weaker positron source.…”

Section: Resultsmentioning

confidence: 59%

Do positrons measure atomic and molecular diameters?

2016

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Abstract. We report on density functional calculations (DFT) of elastic integral scattering cross-sections for positron collisions with argon, krypton, nitrogen and methane. The long-range asymptotic polarization potential is described using higher-order terms going much beyond an induced dipole potential (−α/r 4 ) while the short-range interaction is modeled by two different forms of electron -positron correlation potential (Boroński-Nieminen and Quantum Monte Carlo potentials). The results of both approaches agree quite well with the recent theoretical and measured values. Based on the present and previous theoretical and experimental data we discuss some systematics observed in integral scattering cross-sections below the positronium formation threshold. In particular we point out on the correlation between the values of scattering cross-sections and atomic dimensions.

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“…In those studies, we mainly ascribed that kind of behavior in the TCS to the attractive dipole interaction between the incident positron and the target molecule, which can overcome the Coulomb repulsion at those low impact energies. However, we note that the presence of a virtual state for positron binding at very low energies was also found to contribute to the sharp increase in the TCS for some of those targets (Bettega et al, 2012;Zecca et al, 2012c;and Chiari et al, 2013c). The very low-energy behaviour of the TCSs plotted in Fig.…”

Section: A N-pentanementioning

confidence: 99%

“…8(a) the TCSs measured at the University of Trento for n-pentane (present data), ethane (C 2 H 6 ; Chiari et al, 2013c), and methane (CH 4 ; Zecca et al, 2012c). Note that the overall uncertainties on the TCSs are plotted in that figure.…”

Section: E Comparison Of the Homologous Series Of Molecules C N H 2n+2mentioning

confidence: 99%

Experimental and theoretical cross sections for positron scattering from the pentane isomers

Chiari

Zecca

Blanco

et al. 2016

The Journal of Chemical Physics

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Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present.

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Positron scattering from methane

Cited by 35 publications

References 38 publications

Positron collisions with ethene

Positron collisions with ethene

Do positrons measure atomic and molecular diameters?

Experimental and theoretical cross sections for positron scattering from the pentane isomers

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