Rahla Naghma

Electron impact ionization cross-section of C2, C3, Si2, Si3, SiC, SiC2 and Si2C

Total ionization cross-sections for C2, C3, Si2, Si3, SiC, SiC2 and Si2C molecules have been calculated by electron impact. Spherical complex optical potential formalism has been employed for obtaining the inelastic cross-sections for these molecules. Then by applying complex scattering potential-ionization contribution method, total ionization cross-sections are derived. These cross-sections are calculated in the energy range from ionization threshold to 2 keV. There are no measurements available in the literature to the best of our knowledge with which our results can be compared. The results show a linear relationship between maximum ionization cross-section and square root of the ratio of polarizability to ionization potential, depending on its atomicity. This gives a confirmation for the consistency of the data reported here. Present work is a maiden attempt to find electron impact ionization cross-section for these molecules, except for C2 and C3.

Electron impact total ionization cross sections for atoms with Z = 49-54

Spherical complex optical potential formalism and complex scattering potential–ionization contribution are used to generate electron impact total inelastic and total ionization cross section, respectively, for the atoms In, Sn, Sb, Te, I and Xe. Roothaan–Hartree–Fock calculations are used to approximate the atomic orbital wavefunction and hence to model the target charge densities and static potentials for these atoms. The results for the above targets are presented for energies ranging from ionization threshold to 2000 eV. Graphs are plotted with other theories and measurements wherever available. We have obtained a systematic and uniform result with an overall agreement with other data for all the elements presented here.

Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

Theoretical Formalism To Estimate the Positron Scattering Cross Section

A theoretical formalism is introduced in this article to calculate the total cross sections for positron scattering. This method incorporates positron-target interaction in the spherical complex optical potential formalism. The study of positron collision has been quite subtle until now. However, recently, it has emerged as an interesting area due to its role in atomic and molecular structure physics, astrophysics, and medicine. With the present method, the total cross sections for simple atoms C, N, and O and their diatomic molecules C2, N2, and O2 are obtained and compared with existing data. The total cross section obtained in the present work gives a more consistent shape and magnitude than existing theories. The characteristic dip below 10 eV is identified due to the positronium formation. The deviation of the present cross section with measurements at energies below 10 eV is attributed to the neglect of forward angle-discrimination effects in experiments, the inefficiency of additivity rule for molecules, empirical treatment of positronium formation, and the neglect of annihilation reactions. In spite of these deficiencies, the present results show consistent behavior and reasonable agreement with previous data, wherever available. Besides, this is the first computational model to report positron scattering cross sections over the energy range from 1 to 5000 eV.

Electron induced ionisation of C3 to C6 ethanoates

The present article reports the calculation of electron impact total ionisation cross sections for C3 to C6 ethanoates for the energy range from the ionisation threshold of the target to 5000 eV. Spherical complex optical potential and complex scattering potential ionisation contribution methods were employed to calculate the cross sections. The results presented here show a consistent variation with previous measurements and theoretical values, wherever available. The dependence of the isomeric effect on the ionisation cross section was also studied. A plot of the peak of ionisation cross section against the square root of the ratio of polarisability to ionisation potential and with the number of carbon atoms in each target exhibits strong correlations. The polarisabilities of C5 and C6 ethanoates were estimated from the correlation plot.

Electron induced chemistry of disilane

Theoretical study of electron impact scattering by disilane molecule is reported in this article. Total, elastic, excitation and differential cross sections were computed at low incident energies using the R-matrix method through QUANTEMOL-N. The total cross section calculation was extended to higher energies using spherical complex optical potential formalism. The smooth transition at the overlap of two formalisms around the ionization threshold of the target has helped to predict cross sections over a wide energy range from 0.1 eV to 5 keV. The resonance position predicted by the present static exchange and static exchange plus polarization models at 3.3 and 3.0 eV respectively agrees quite well with previous theoretical and experimental results. The inclusion of polarization effects in the calculation has considerably improved the position of the resonance from the previous static exchange calculation. In general the results obtained for total, elastic and differential cross sections show reasonable agreement with the experiment. The excitation cross section of disilane from ground state to various excited states is reported for the first time.

Calculations of electron collision and ionisation of rare gas dimers

Thresholds to 2000 eV electron impact total inelastic cross-sections for rare gas dimers were calculated employing a spherical complex optical potential formalism. From these inelastic cross-sections, total ionisation cross-sections are derived by applying a complex scattering potential-ionisation contribution method. This is a maiden attempt to study the total ionisation cross-section for most of these targets. To the best of our knowledge, no measurements or calculations are available for all the targets in the literature with which we can compare our results. The results show a linear relationship between maximum ionisation cross-section and target radius, depending on its size. Such dependence can confirm the consistency of the data presented here.

Electron impact total ionisation cross sections for simple bio-molecules: a theoretical approach

In this article, we have reported electron impact total ionisation cross sections for the bio-molecules pyridine, pyrimidine, n-propylamine, urea, formamide and N-methylformamide from ionisation threshold to 2000 eV. The present calculations are based on the spherical complex optical potential formalism and complex scattering potential ionisation contribution method. The results obtained for pyridine and pyrimidine are compared with available theoretical and experimental results and are found to be in excellent agreement with existing data. The ionisation cross sections for other molecules are reported for the first time. An interesting relation between the peak of inelastic and ionisation cross sections with target parameters is also reported. It was found that both the cross sections at their maximum depend linearly with these parameters, confirming the consistency of the values reported here.

Electron scattering from germanium tetrafluoride

This paper describes the use of two methodologies to find the electron impact total cross sections (TCS) for GeF4 molecule from 1–5000 eV. The ab initio R-matrix method is used at low impact energies and the spherical complex optical potential (SCOP) formalism at intermediate to high energies. The TCS from both formalisms match quite well at the overlapping energy (∼12 eV) allowing us to predict the cross section for such a wide energy range. Besides TCS, calculations for electronic excitation, rotational excitation, momentum transfer and differential elastic cross sections are also reported using the R-matrix method. A broad resonant feature at 5.69 eV due to degenerate 2B1, 2B2 and 2B3 states is observed, revealing the probability of anion formation by an electron attachment process and further decay to neutral and negative ion fragments. The electronic and rotational excitation cross sections for e-GeF4 scattering are reported for the first time.

Electron impact ionisation cross section for organoplatinum compounds

ABSTRACT This article reports electron impact ionisation cross sections for platinum-based drugs viz., cisplatin (H6N2Cl2Pt), carboplatin (C6H12N2O4Pt), oxaliplatin (C8H14N2O4Pt), nedaplatin (C2H8N2O3Pt) and satraplatin (C10H22ClN2O4Pt) complexes used in the cancer chemotherapy. The multi-scattering centre spherical complex optical potential formalism is used to obtain the inelastic cross section for these large molecules upon electron impact. The ionisation cross section is derived from the inelastic cross section employing complex scattering potential–ionisation contribution method. Comparison is made with previous results, where ever available and overall a reasonable agreement is observed. This is the first attempt to report total ionisation cross sections for nedaplatin and satraplatin complexes.