Electron Impact Total Cross Sections Research Articles

Calculation of electron scattering cross sections for Anthracene, Pyridine and Warfarin molecules over energy range 10–30000 eV

This paper reports electron impact total cross section, total elastic, total inelastic and differential cross sections for molecules Anthracene, Pyridine and Warfarin having been computed using the independent atom model with screening-corrected additivity rule over an incident energy range of 10–30000 eV. The calculations are performed with relativistic (Dirac) partial-wave for scattering by applying a local central interaction potential V(r). A model spherical complex optical potential is used for calculations. Good agreement is achieved in intermediate and high-energy zones.

Theoretical electron impact total cross sections for tetrahydrofuran (C4H8O)

We report electron impact total cross sections for tetrahydrofuran (C4H8O) from ionization threshold to 5 keV. We have employed Spherical Complex Optical Potential (SCOP) to calculate total cross sections Q T , total inelastic cross sections Q inel and total elastic cross sections Q el and have used Complex Scattering Potential – ionization contribution (CSP-ic) formalisms to compute total ionization cross sections Q ion and summed total excitation cross sections ∑ Q exc . We have compared our cross sections with available experimental as well as theoretical results and have found good agreement wherever available. This is the maiden attempt to report the total excitation cross sections for this target.

Electron-impact total cross sections for inelastic processes for furan, tetrahydrofuran and 2,5-dimethylfuran

We report total inelastic, total ionisation and summed total excitation cross sections for electron scattering on furan, tetrahydrofuran (THF) and 2,5-dimethylfuran at energies between the ionisation threshold and 5 keV. We have employed the spherical complex optical potential formalism (SCOP) to calculate the total inelastic cross sections (Qinel) and have used complex scattering potential-ionisation contribution (CSP-ic) method to derive total ionisation cross sections (Qion) and summed total excitation cross sections (∑Qexc) from the calculated Qinel. We have also computed Qion for these molecules using binary-encounter-Bethe (BEB) approach. We have compared our total cross sections (TCS) with available experimental as well as previous theoretical results and have found good agreement. The results are presented graphically as well as numerically.

0.1–2000 eV electron impact cross sections for dichlorine monoxide

Scattering dynamics of dichlorine monoxide (Cl2O) molecule by electron impact is investigated as a function of electron energy and scattering angle. Electron impact total cross sections for Cl2O over an extensive range of impact energies from 0.1 to 2000eV are reported in this article. Below the ionization threshold of the target, the ab initio R-matrix method and above this incident energy spherical complex optical potential formalism are used for cross section calculation. The total cross section obtained from both theories merges smoothly at the overlapping energy. The resonances obtained using DZP basis sets are located at 1.883, 3.592, 5.205 and 7.326, 8.206, 8.301, 8.452, 9.369eV and that with 6-31G* basis sets are identified at 1.944, 3.566, 5.183, 5.261, 5.658, 8.738 and 9.187eV with the possibility of negative ions formation. This is the first attempt to calculate the differential, and momentum transfer cross sections for Cl2O molecule.

Electron impact total cross sections for components of DNA and RNA molecules

Present paper reports electron impact total cross sections (QT), total elastic cross sections (Qel) and total inelastic cross sections (Qinel) for DNA and RNA nucleic bases as well as Phosphoricacid from 20eV to 2000eV. These components include uracil (C4H4N2O2), thymine (C5H6N2O2), cytosine (C4H5N3O), adenine (C5H5N5), guanine (C5H5N5O) and phosphoric acid (H3PO4). We have employed spherical complex optical potential (SCOP) formalism to calculate these total cross sections. Since DNA and RNA are complex molecules, we have used the group additivity rule which incorporates molecular properties of the target to evaluate these cross sections rather than the atomic properties as in case of independent atom model (IAM) and screened corrected additivity rule (SCAR) employed in previous works. The present results for these complex biomolecules are compared with previous data wherever available.

Electron impact total cross sections for hydrogen molecule from 0.01 eV to 2 keV

In the present work, we calculate electron impact total cross section for H2 molecule over wide range of incident energies starting from 0.01 eV to 2 keV. The present results are examined as function of incident energies and compared with available results.

Scattering of N2O on electron impact over an extensive energy range (0.1 eV–2000 eV)

We report electron impact total cross sections, Q(T), for e-N(2)O scattering over an extensive range of impact energies approximately from 0.1 eV to 2000 eV. We employ an ab initio calculation using R-matrix formalism below the ionization threshold of the target and above it we use the well established spherical complex optical potential to compute the cross sections. Total cross section is obtained as a sum of total elastic and total electronic excitation cross sections below the ionization threshold and above the ionization threshold as a sum of total elastic and total inelastic cross sections. Ample cross section data for e-N(2)O scattering are available at low impact energies and hence meaningful comparisons are made. Good agreement is observed with the available theoretical as well as experimental results over the entire energy range studied here.

Total cross-section calculations for electrons colliding with molecular nitrogen over an extensive energy range from meV to keV

We report a comprehensive study of the electron impact total cross-sections for molecular nitrogen for impact energies from 0.01 eV to 2000 eV. Ab initio calculations are performed using the R-matrix formalism at low impact energies (up to ∼15 eV), while the Spherical Complex Optical Potential formalism is utilised beyond this range. The two methods are consistent at the transition energy, which enables us to provide data for such an extensive range. The results obtained show overall good agreement with the available data.

Influence of sulphur atom on the qualitative behavior of electron impact total cross sections of some sulphur containing molecules

Absolute elastic differential cross sections (DCS) have been measured experimentally for several sulphur containing molecules such as SF6, CS2, DMS and DMSO using a novel high resolution electron spectrometer. The measured DCS’s were extrapolated in the forward and backward angles using a tenth order legendre polynomial based least squares fitting technique. Total cross sections (TCS) were determined by integrating the DCS over all angles for each incident energy. The influence of the sulphur atom on the molecular TCS is studied by comparing the qualitative behavior of electron impact cross sections for the sulphur containing molecules against the TCS of the sulphur atom at each incident energy. Theoretical calculations based on independent atom model are also presented as a guide to understand the nature of the electron-molecule collision processes measured in this study.

Total cross-sections for positron and electron scattering from α-tetrahydrofurfuryl alcohol

In this paper, we report original measurements of total cross-sections (TCSs) for positron scattering from an important biomolecule, α-tetrahydrofurfuryl alcohol (THFA). The energy range of these measurements was 0.15–50.15 eV, whereas the energy resolution was ∼260 meV. In addition, we report theoretical results, calculated within the independent-screened additivity rule (IAM-SCAR) formalism, on the corresponding electron impact total cross-sections. In this case, the energy range is 1–10 000 eV. With the advent of new particle track simulation codes, which incorporate accurate atomic and molecular data in order to provide interaction details at the nanoscale, interest in positron and electron TCSs has enjoyed something of a recent renaissance as they specify the mean free path between collisions in such codes. Because the present data are, to the best of our knowledge, the first TCSs to be reported for positron scattering from THFA, they fill an important void in the knowledge available to us from the literature.

Electron interactions with plasma processing gases – Progress of magnetized electron-impact total cross section measurement system(ELECS-1)

Electron-impact cross sections for molecular targets, including their radicals, are important in developing plasma reactors and testing various plasma processing gases. However, we suffer from lack of theoretical and experimental electron-impact cross section data for plasma processing gas, such as plasma etching and deposition processes. Thus, in this work, the total cross sections for electron scattering from plasma processing gases has been developed using magnetized beam formation in the low- and intermediate-energy region.

Total cross sections for positron and electron scattering from pyrimidine

In this paper we report original measurements of total cross sections for positron scattering from the important biomolecule pyrimidine. The energy range of these measurements was 0.3–45 eV, while the energy resolution was ∼260 meV. In addition, we report theoretical results, calculated within the independent atom–screened additivity rule (IAM-SCAR) formalism, for the corresponding electron impact total cross sections. In that case the energy range is 1–10 000 eV. Total cross sections are very important input data for codes that seek to simulate charged-particle tracks in matter, as they define the mean-free path between collisions. As the present data and computations are to the best of our knowledge the first total cross sections to be reported for either positron or electron scattering from pyrimidine, they fill an important void in our available knowledge in the literature.

Measurement of the absolute total electron impact cross section on Cs atoms using a magnetooptical trap

Laser cooling and trapping of neutral atoms has been employed for the measurement of the total electron impact cross sections of the ground state 62 S 1/2 of 133Cs atoms in the energy range from 80 to 500 eV. The total electron impact cross sections of the cold Cs atoms in the MOT were measured by observing the decay of the MOT after the interaction with the electron beam, and were found to depend only on the electron flux and not on the total number of atoms in the MOT. We confirm and extend the existing data on these measurements.

New measurements of absolute total cross sections for electron impact on caesium using a magneto-optical trap

A new magneto-optical trap designed specifically for the measurement of absolute electron impact cross sections is described. Experimental results for electron impact total cross sections involving 62S ground state Cs are presented over the energy range 5–200 eV. Significant disagreement is obtained between our experimental data and convergent close coupling (CCC) or Breit–Pauli R-matrix calculations at the lower energies. Above 100 eV our data overlap earlier measurements from this laboratory made with a completely different apparatus and agree well with the CCC results. A comparison is made with other measurements using more conventional techniques.

Total and ionization cross sections of electron scattering by fluorocarbons

Electron impact total cross sections (50–2000 eV) and total ionization cross sections (threshold to 2000 eV) are calculated for typical plasma etching molecules CF4, C2F4, C2F6, C3F8 and CF3I and the CFx (x = 1–3) radicals. The total elastic and inelastic cross sections are determined in the spherical complex potential formalism. The sum of the two gives the total cross section and the total inelastic cross section is used to calculate the total ionization cross sections. The present total and ionization cross sections are found to be consistent with other theories and experimental measurements, where they exist. Our total cross section results for CFx (x = 1–3) radicals presented here are first estimates on these species.

Electron scattering from C4H6 andC4F6molecules

Absolute electron-impact total cross sections (TCSs) for C4H6isomers (1, 3-butadiene and 2-butyne) and for hexafluoro-2-butyne (C4F6)have been measured in a linear electron-beam transmission experiment as afunction of impact energy, between 0.5 and 370 eV. For the C4H6molecule distinct differences in the shape and magnitude of TCS energydependences of both isomers are apparent at low energies. In the 1, 3-butadieneTCS curve, the enhancement below 1.2 eV, the narrow maximum centred around3.2 eV and the dominant broad peak at 9–9.5 eV are easily distinguishable; a veryweak shoulder is located near 8 eV. The TCS energy function of 2-butynedemonstrates a remarkable resonant-like maximum located near 3.6 eV andmuch broader enhancement centred at 8 eV. Above 50 eV both C4H6curves merge together. The hexafluoro-2-butyne TCS has the maximum near 8 eVand very broad enhancement spanning between 20 and 80 eV; weak shouldersnear 3 and 6 eV are also noticeable. The effect of perfluorination is indicated.

Electron impact total cross sections of CHx,NHx and OH radicals vis-à-vis their parentmolecules

Various total cross sections for the impact of electrons on free radicalsCHx, NHx and OH are calculated at intermediate to high energies.The known ionization data on the parent molecules CH4, NH3 andH2O are employed to extract total ionization cross sections of therespective radicals using total inelastic cross sections, which we havecalculated through a complex optical potential. The results give an upper bound of the total ionization cross section in the energy regionaround 100 eV, and are in suitable harmony with available experimentaldata at higher energies.

Total and elastic cross-sections for electron and positron scattering from OCS molecule: A comparative study with CO2

We have carried out a joint experimental and theoretical study on determination of total and elastic cross-sections for electron and positron impact on OCS molecules. For total cross-section measurements, impact energies are from 0.7 to 600 eV for electron collisions and 0.8 to 600 eV for positron collisions. For elastic scattering, only electron impact has been studied from 1.5 to 100 eV. Our present measurements for total cross-sections for electron impact are found to agree extremely well with the measurements of Dababneh et al. (1982) in the entire energy region studied. The results by Szmytkowski et al. (1994) are consistently larger by 20% above 2 eV, and, in particular, are larger by a factor of two in the 1.2 eV resonance region. The present theory for elastic scattering is in good agreement with the present measurement, and has been employed for understanding the dynamics. The total cross-section recommended here is probably the best in accuracy as of today although further studies would be helpful.

Experimental studies on electron scattering from atoms and molecules: the state of the art

Electronatom/molecule scattering has been the subject of intense research activity, both experimentally and theoretically, for nearly a century, yet particularly for electronmolecule scattering our...

Various total cross-sections for electron impact on , and

Cross-sections for the impact of electrons having energy Ei =50 - 5000 eV are evaluated for polyatomic molecules \(\), \(\), \(\), \(\), \(\) and \(\). Total (complete) cross-sections and total inelastic cross-sections are calculated for these targets by employing the atomic optical potentials and additivity rules. A variant of our previous work, to be called MAR-SC has been developed for molecules such as the present ones, where two approximately independent scattering centres can be identified. We find a good general accord of our theoretical values with various experimental data. Also given presently is an analytical fit \(\), incorporating polarizability \(\), for the high energy total cross-sections for 18-electron targets. Tentative upper and lower limits for the electron molecule total ionization cross-sections are identified and a break-up into elastic and inelastic contributions is exhibited.