Phenomenology and scaling of electron scattering cross sections from “almost spherical” molecules over a wide energy range

Collisions of intermediate to high energy electrons are considered with S-atoms as well as H 2 S, OCS and SO 2 molecules as targets. We employ e − -atom total cross sections calculated in the complex optical potential, to calculate e − -molecule total cross sections in a simple and a modified Additivity Rule. Our total (elastic + inelastic) cross sections above 50 eV, fare reasonably well as compared to various experimental and theoretical data. The calculated inelastic cross sections serve as the upper limit of total ionization cross sections. Results are presented graphically from about 10 to 5000 eV.

“…Lower curves: , Q inel (present); ---, Q Ion , AR (3) than the present values, upto about 1000 eV (Fig. 3).…”

Section: Results Discussion and Conclusionmentioning

confidence: 45%

“…Around 100 eV the cross sections are not governed simply by the number of target electrons or typical bond lengths [1][2][3][4]. In , MAR (present); , Dababneh et al [5];…”

Section: Results Discussion and Conclusionmentioning

confidence: 99%

See 1 more Smart Citation

Total cross sections of electron collisions with S atoms; H2S, OCS and SO2 molecules (Ei ≥ 50 eV)

Joshipura

Vinodkumar²

1997

“…They [19] mention that the fit parameter d (in theirs it is B) is related to the bond length of some hydrides molecules, such as NH 3 , CH 4 , H 2 O, H 2 S and SiH 4 . Recently March et al [29] have analyzed total cross sections for electron scattering on "quasi spherical" molecules (CH 4 , SiH 4 and GeH 4 ) over a wide energy range. Simple analytical formulae (Eσ = const.)…”

Section: The Semi-empirical Formulamentioning

confidence: 99%

Total cross sections for electron scattering from molecules: NH3 and H2O

Liu

Sun

et al. 1997

By developing the semi-empirical formula recently obtained for total cross sections of electron scattering from diatomic molecules in the intermediate-and highenergy range, we calculate the total cross sections for electron scattering from molecules (NH 3 and H 2 O) over an incident energy range of 10-1000 eV. The total cross sections have also been calculated by using the complex optical potential and the additivity rule. Compared with other available experimental and calculating data, excellent agreements have been achieved. The developed semi-empirical formula reflects that total cross sections for electron scattering from NH 3 and H 2 O in the intermediate-and high-energy range quantitatively depend on the bond length.

“…Moreover, some insight and information on the type of interaction can be gained. In our recent studies [10][11][12][13] we have measured the electron scattering total cross sections on three families of molecules in the 70-4000 eV energy range and described these cross sections from a few tens of eV to 4000 eV by a simple analytical formula using two or four adjustable parameters. In this paper we present a partitioning scheme for electron scattering on noble gases, where the total and the partial cross sections are approximated by analytical formulae.…”

Section: Introductionmentioning

confidence: 99%

Analytical partitioning of total cross sections for electron scattering on noble gases

Brusa

Karwasz

Zecca

1996

Self Cite

Empirical analytical formulae are proposed, aiming at the description of partial cross sections for electron scattering on noble gases. Selected measurements of total, excitation and ionization cross sections for these gases have been fitted by these analytical formulae in the 20-5000 eV energy range. The elastic cross sections, obtained as the difference, compare quite well with the elastic experimental data for all gases but for helium. The difference elastic cross sections were fitted by a cross section formula derived from electron scattering on a single or double Yukawa potential in the first Born approximation. Our analysis shows a good consistency between partial and total cross sections for the four heavier gases. For helium, we suggest the possibility of large errors in the high energy part of total, elastic and excitation cross sections. The analytical expressions given in this paper allow to reproduce the total and partial cross sections within the measurement errors in a large energy range from a few tens of eV, up to several keV. PACS: 34.80.Bm; 34.80.Dp I IntroductionElectron-atom and electron-molecule cross section data are important in a large variety of applications and fields (see for instance [1]). In these applications, cross section values as a function of the energy are needed as input data in calculations, modelling and Monte Carlo simulations. Some examples can be found in [2] for plasma chemistry, in [3] for fusion plasma research, and in [4] for electron and positron slowing down and diffusion in solids. Many applications of electron impact ionization cross sections (from gas discharges to astrophysics and atmospheric physics) presented by different authors, are reported in [5].An obvious help to these computational works can be provided by analytical or empirical expressions describing the cross sections data [6][7][8][9]. Where these formulae are not available, tables of data and interpolations or extrapolations must be used. Analytical representation are also interesting by themselves giving direct information on the consistency of different data sets, and allowing extrapolation of cross section data at energies where experimental measurements do not exist. Moreover, some insight and information on the type of interaction can be gained. In our recent studies [10-13] we have measured the electron scattering total cross sections on three families of molecules in the 70-4000 eV energy range and described these cross sections from a few tens of eV to 4000 eV by a simple analytical formula using two or four adjustable parameters. In this paper we present a partitioning scheme for electron scattering on noble gases, where the total and the partial cross sections are approximated by analytical formulae.To date, a relatively large number of good quality electron scattering measurements on noble gases cover an energy range from less than 1 eV to 3000 eV. The works of de Heer and Jansen [14] on He, de Heer et al. [15] on Ne, Ar, Kr, Xe, present a comprehensive evaluation of semiempirical values...