Czesław Szmytkowski

Absolute electron-scattering total cross section measurements for noble gas atoms and diatomic molecules

Absolute electron-scattering total cross sections for noble gas atoms (He, Ne, Ar, Kr, and Xe) and H,, N, , CO, NO, and 0, molecules have been measured at impact energies between 0.5 and 250eV by the linear transmission method with the same experimental set-up for all the investigated targets. Generally, our total cross sections have been found to be in good agreement with other data with respect to shape. Some systematic discrepancies in magnitude still exist between results of different groups, especially at the lowest applied energies and in the energy range where the cross sections peak. At these energies, new measurements should be carried out before establishing a reference set of data.

Absolute total electron-scattering cross sections of N2O and OCS in the low-energy region

Abstract Absolute total cross sections for electron scattering from CO, CO 2 and OCS molecules at low energies have been measured. An increase of the cross sections due to the formation of negative ion resonance states was observed.

ABSOLUTE TOTAL CROSS SECTIONS FOR ELECTRON-WATER VAPOUR SCATTERING

Abstract Measurements are made on water vapour in the energy range 0.5–80 eV to give absolute total electron-scattering cross sections. The total cross section function obtained increases sharply at energies below 3 eV and shows a structureless, very broad flat maximum around 9 eV. The results presented here show some differences from those obtained in other laboratories.

Absolute total cross section measurements for electron scattering on benzene molecules

The absolute total cross section for electron scattering on C,H, molecules has been measured in two distinct electron-transmission experiments for impact energies between 0.6 eV and 3.5 keV. The present results are compared with other total cross section experimental data.

Absolute total electron-scattering cross section of H2S

A considerable number of total cross-section measurements have been carried out in recent years for electron-molecule scattering. Nevertheless, there is still a need for further measurements because even for relatively simple triatomic molecules the existing data are only fragmentary [l]. At the same time, progress has been made in the theoretical treatment of the scattering of low-energy electrons by molecules L31. Recently, calculations have been performed by Gianturco and Thompson [4] and Jain and Thompson [5] for e--H,S scattering at impact energies below 10 eV. Their theoretical results have demonstrated that in this energy region transient negative-ion resonance states play an important role in the electronH2 S molecule scattering process. H2 Sresonance states have been proposed earlier by Fiquet-Fayard et al. [6] and Azria et al. [7,8] for the interpretation of their experimental studies on electron dissociativeattachment processes for the H2S molecule. The transmission experiments of Sanche and Schulz [9] and, particularly, measurements of vibrational excitation cross sections by Rohr [lo] and Tronc et al. [ 1 l] also indicated the existence of resinant states. The present work reports the results of measurements of the absolute total electron-scattering cross section of H,S by the linear transmission method. The measurements were carried out in the energy range in which electron-molecule scattering is usually dominated by resonance processes.

Electron scattering from C4H6 and C4F6 molecules

Absolute electron-impact total cross sections (TCSs) for C4H6 isomers (1, 3-butadiene and 2-butyne) and for hexafluoro-2-butyne (C4F6) have been measured in a linear electron-beam transmission experiment as a function of impact energy, between 0.5 and 370 eV. For the C4H6 molecule distinct differences in the shape and magnitude of TCS energy dependences of both isomers are apparent at low energies. In the 1, 3-butadiene TCS curve, the enhancement below 1.2 eV, the narrow maximum centred around 3.2 eV and the dominant broad peak at 9–9.5 eV are easily distinguishable; a very weak shoulder is located near 8 eV. The TCS energy function of 2-butyne demonstrates a remarkable resonant-like maximum located near 3.6 eV and much broader enhancement centred at 8 eV. Above 50 eV both C4H6 curves merge together. The hexafluoro-2-butyne TCS has the maximum near 8 eV and very broad enhancement spanning between 20 and 80 eV; weak shoulders near 3 and 6 eV are also noticeable. The effect of perfluorination is indicated.

Electron scattering from CF4 and CCl4. Total cross section measurements

Abstract Absolute total cross sections for e − -CF 4 and e − -CCl 4 scattering were measured using the linear transmission technique with energy ranging from 0.5 to 200 eV. A comparison is made with other measurements and calculations.

Elastic cross-section calculations for electron collisions with XY4 (X=Si, Ge; Y=H, F, Cl, Br, I) molecules

Abstract We report calculations of integral cross-section and differential cross-section for intermediate- and high-energy (20–2000 eV) elastic electron collisions with tetrahedral compounds of silicon and germanium: SiH4, SiF4, SiCl4, SiBr4, SiI4, GeH4, GeF4, GeCl4, GeBr4 and GeI4. The calculations have been carried out using an independent atom model with static-polarization model potential. The present results are compared with available experimental and theoretical data. For collision energies higher than 100 eV, results of present theoretical calculations are in satisfactory agreement with experimental data.

Total cross sections for electron scattering with some C3 hydrocarbons

Absolute total cross sections (TCSs) for electron scattering from two C3H4 isomers (allene and propyne) and from propane (C3H8) have been measured in a linear electron-beam transmission experiment for impact energy ranging from 0.5 to 370 eV. Low-energy TCS functions for C3H4 are dominated by prominent structures: a resonant-like enhancement of the cross section for allene peaks at around 2.3 and 3.4 eV for propyne, while very broad enhancement is centred at 9.5–10 and 8.0–8.5 eV for allene and propyne respectively. Some supplementary weak features are also discernible. The general shape of cross sections for both C3H4 isomers is similar except that the cross section enhancements are at different locations. In addition, the TCS for propyne has been compared with cross sections for other open-chain hydrocarbons with three carbon atoms, i.e. propene (C3H6) and propane (C3H8), and the effect of the multiplicity of the C–C bond on the low-energy scattering is demonstrated.

Absolute total cross sections for electron-CO2 scattering at energies form 0.5 to 3000 eV

Employing two different experimental techniques, absolute total cross sections for e--CO2 scattering have been measured over a very wide energy range between 0.5 and 3000 eV. The cross section function exhibits a sharp increase below 1.5 eV and a resonant maximum around 3.8 eV. It then rises again up to a broad maximum near 30 eV and then decreases slowly. A very broad feature was observed centred at an energy of about 300 eV and extending from about 200 to 600 eV. Comparison is made with other available measurements and calculations.