Elastic cross sections for electron scattering from GeF4: Predominance of atomic-F in the high-energy collision dynamics

Abstract

We report absolute differential cross sections (DCSs) for elastic electron scattering from GeF4. The incident electron energy range was 3–200 eV, while the scattered electron angular range was typically 15°–150°. In addition, corresponding independent atom model (IAM) calculations, within the screened additivity rule (SCAR) formulation, were also performed. Those results, particularly for electron energies above about 10 eV, were found to be in good quantitative agreement with the present experimental data. Furthermore, we compare our GeF4 elastic DCSs to similar data for scattering from CF4 and SiF4. All these three species possess Td symmetry, and at each specific energy considered above about 50 eV their DCSs are observed to be almost identical. These indistinguishable features suggest that high-energy elastic scattering from these targets is virtually dominated by the atomic-F species of the molecules. Finally, estimates for the measured GeF4 elastic integral cross sections are derived and compared to our IAM-SCAR computations and with independent total cross section values.

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

“…As is evident from the level of agreement between the present experimental results and the IAM-SCAR calculation, the atomic-like effects are dominant in the scattering dynamics, even for the molecular structures. These features have been observed in several cases [45][46][47][48] at higher impact energies above 50 eV. But, it is worth noting that the atomic form factor of the S atom (atomic number: 16) plays an important role in the elastic scattering from OCS and CS 2 , more so than the other constituents of C (6) and O (8), over the impact energy from a few eV to 200 eV.…”

“…As such, new measurements are compared with the existing experimental and theoretical data below 3 eV and above 100 eV. Also, following on from our series of studies on "atomic-like" effects which appear to prevail in high-energy electron scattering from molecules, [45][46][47][48] we further extend this study by comparing the elastic DCSs for OCS and CS 2 , where collisions with atomic sulphur appear to dominate the scattering dynamics. Further evidence lending support to this behavior is demonstrated by our IAM-SCAR results.…”

“…68 Moreover, this approach seems to be inherently suitable for electron scattering from a heavy atom-rich molecule, such as GeF 4, in which its application ranges down to 7 eV. 48 Furthermore, for the polar molecule OCS, additional dipole-excitation cross sections can be calculated through the IAM-SCAR and rotational contribution method 62, 69 which has been successfully used for other polar molecules such as H 2 O. 70 Thus, the range of validity of our approach may be extended to energies possibly below 10 eV.…”

“…Further improvements to the original formulation, 63 such as the inclusion of screening effects and in the description of the electron's indistinguishability, 59 finally led to a model which provides a good approximation for electron-molecule scattering over a very broad energy range. [46][47][48] To calculate the cross sections for electron scattering from molecules, we follow the IAM by applying a coherent addition procedure, commonly known as the additivity rule (AR). In this approach, the molecular scattering amplitude is derived from the sum of all the relevant atomic amplitudes, including the phase coefficients, therefore leading to the molecular DCSs for the molecule in question.…”

Cross sections for elastic scattering of electrons by CF3Cl, CF2Cl2, and CFCl3

“…In our research program at Sophia University for such series of molecules, we have reported absolute differential cross sections (DCSs) for elastic electron scattering from CH n F 4-n (n = 0-4), 1, 2 XY 4 (X = C, Si, Ge; Y = H, F, Cl), [3][4][5][6] CX 3 Y (X = H, F; Y = H, F, Cl, Br, I), 7,8 C 3 H 8 and C 3 F 8 , 9 C 6 H 5 X (X = CH 3 , CF 3 ), 10 and CO 2 , OCS, and CS 2 . 11, 12 Those results have been compared with the corresponding elastic cross sections in Ne, Ar, Kr, and Xe (see, e.g., Ref.…”