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We calculate electron impact partial and total ionization cross sections of R-carvone (C10H14O), 2-butanol (C4H10O), imidazole (C3H4N2), and 2-nitroimidazole (C3H3N3O2). We have used the Binary Encounter Bethe (BEB) model to obtain total electron impact ionization cross sections (TICSs). The modified BEB method in combination with mass spectrum data of the molecules is used to calculate the partial ionization cross section (PICS) of the cationic fragments dissociating from the parent molecule. Our PICS data for R-carvone and 2-butanol are in good agreement with the experimental data for all the cation fragments along with the TICS data. For imidazole and 2-nitroimidazole, the estimates of the PICS are reported for the first time in the present study. We have found that both the modified BEB method and the mass spectrum dependence method work effectively to estimate PICS if we have information about the appearance energies and relative abundance data of the target under investigation. [ABSTRACT FROM AUTHOR]

The scattering cross-sections for positron-biomolecule interaction are an essential input for the Monte-Carlo simulation techniques. In the present work, we have reported the elastic integral, differential, momentum transfer, and total ionization cross-sections for scattering of positron from 2H-pyran, 4H-pyran, and pyrrole molecules. The single-center expansion (SCE) method is employed for the elastic scattering calculations and the binary-encounter-Bethe model for ionization. We have also reported the elastic integral and differential cross-sections for benzene and furan, which are structurally similar to the pyran isomers and pyrrole, respectively, and compared them with the experimental and theoretical data available in the literature to validate the efficacy of the SCE method and the codes used. A comparative analysis of the elastic cross-sections for the isomers: 2H-pyran and 4H-pyran, and the pyrrole molecule that is isoelectronic with furan is also presented. [ABSTRACT FROM AUTHOR]

We have calculated the electron and positron impact ionization of a set of molecules, S F 6 − n H n (n = 0 − 6) , S C l n (n = 1 − 6) , S F n − 1 C l (n = 1 − 6) and S F 5 X (X = C N , C F O) , for which there are much fewer data in the literature. We have optimized the targets, and their electric polarizability is calculated along with their orbital binding and kinetic energies within the Hartree–Fock approximation that serve as input to the Binary Encounter Bethe (BEB) model for both electron and positron ionization. Most of the targets are investigated for the first time, apart from S F 6 , for which we compared our data with various experimental and theoretical data, giving us a good comparison. [ABSTRACT FROM AUTHOR]

In this article, we report the electron impact ionization cross sections for atoms Si, P, S, Sc, Cr, Mn, Co, Zn, Ga, Ge, Nb, Rh, and Cd, having applications in different areas of applied science and technology. The energy regime for the calculation is from the ionization threshold of the target to 2000 eV. We have employed the spherical complex optical potential method to calculate inelastic cross sections. A semiempirical complex scattering potential ionization contribution method is then used to estimate the ionization cross section from the inelastic cross section. In general, good agreement between the present results with available theoretical datasets and measurements are observed. The prime focus of this study was to investigate electron impact ionization phenomena in less studied targets. The results obtained are found to be quite encouraging. The values presented here are reasonable estimates of cross section for all the atoms studied. PACS Nos.: 34.50.-s, 34.80.Bm, 34.50.Gb. Nous presentons ici les sections efficaces d'ionisation par impact electronique pour differents atomes, nommement Si, P, S, Sc, Cr, Mn, Co, Zn, Ga, Ge, Nb, Rh et Cd, qui trouvent des applications dans differents domaines de science et de technologie. Le domaine d'energie des calculs va du seuil d'ionisation de l'atome jusqu'a 2000 eV. Nous utilisons le potentiel optique complexe spherique pour calculer les sections efficaces inelastiques. Nous utilisons alors une methode semi-empirique complexe de contributions potentiel-ionisation lors de collisions, afin d'estimer la section efficace d'ionisation a partir de la section efficace inelastique. En general, nous avons un bon accord entre nos resultats et les resultats theoriques et experimentaux trouves dans la litterature. L'idee premiere de ce travail est d'etudier les phenomenes d'ionisation par impact electronique sur des cibles moins etudiees. Les resultats obtenus sont tres encourageants. Les valeurs presentees ici sont des estimes raisonnables des sections efficaces pour tous les atomes etudies. [Traduit par le Redaction], 1. Introduction Study of electron collisions with atoms gives insight into the rudimentary interactions of many-electron systems. These primary physical processes analyze quantitatively the behavior of ionized gases produced by [...]

Two independent methods, namely, Binary-encounter Bethe (BEB) and complex scattering potential-ionization contribution (CSP-ic) methods, are employed to calculate the total ionization cross section (Qion) for cyclic organic molecules from ionization threshold to 5 keV for which there is a paucity of data in the literature. The Qion calculated with the (BEB/ωB97X) combination is found to give good agreement with the experimental results, the CSP-ic method, and the Qion calculated from Irikura orbital energies. The Qion for most of the targets are calculated for the first time over such a wide energy range. Hence, to check the consistency and reliability of the present data, we have also computed the static polarizability for all the targets and the variation of maximum ionization cross section (Qion,max) with polarizability is studied. A linear relationship is observed between these quantities indicating the consistency and reliability of the present Qion data. The targets studied are important for industrial applications, radiation biology, and astrophysics. [ABSTRACT FROM AUTHOR]

The molecular R-matrix calculation is performed for the low energy electron scattering from propene to obtain total and rotational excitation cross sections. The rotational excitation cross sections are calculated for the transitions involving levels from j = 0 to j = 5. These cross sections are used for calculating their corresponding rate coefficients for the temperature range 30–5000 K. The rate coefficients at such temperatures have relevance in the interstellar medium as well as in the plasma environment. The spherical complex optical potential and complex scattering potential- ionization contribution methods are used for high energy calculation of the total cross section (Qtot) and ionization cross section (Qion), respectively, for both electron and positron scattering. The present Qtot results give reasonable agreement with previous experimental data. We have detected a π * shape resonance for electron scattering at 3.71 eV due to 2A″ scattering state, which is in accordance with the experimental results. However, no such resonance is observed in the positron scattering calculations. The cross sections reported here show good comparison with existing data, validating present calculations and its reliability. [ABSTRACT FROM AUTHOR]

Calculation of electron impact total and ionization cross sections for Sr, Y, Ru, Pd, and Ag atoms were performed using spherical complex optical potential and complex scattering potential-ionization contribution methods. The complex optical potential model is formulated from the target parameters and the atomic charge density. The spherical charge densities are in turn derived from the Roothaan--Hartree--Fock wavefunctions defining the atomic orbital of the target. In the present study cross sections are computed in the energy range from ionization threshold to 2000 eV. The results obtained are compared with other theories and measurements wherever available and were found to be quite consistent and uniform. In general, present data show an overall reasonable agreement with other results. Dependence of total cross sections on the number of target electrons and peak of ionization cross section on target parameters were also found to be consistent with previous observations. PACS Nos.: 34.50.-s, 34.80.Bm, 34.50.Gb. Nous avons calcule les sections efficaces totales d'impact electronique et d'ionisation pour des atomes de Sr, Y, Ru, Pd et Ag, en utilisant un potentiel optique complexe spherique et une methode de contributions complexes potentiel- ionisation de diffusion (CSP-ic). Le potentiel optique complexe est formule a partir des parametres de la cible et de la densite de charges atomiques. Les densites spheriques de charge sont a leur tour obtenues des fonctions d'onde de Roothan-Hartree-Fock qui decrivent les orbites atomiques de la cible. Nous calculons ici les sections efficaces pour des energies allant du seuil d'ionisation jusqu'a 2000 eV. Nos resultats sont coherents et uniformes et nous les comparons avec d'autres valeurs theoriques et experimentales lorsqu'elles existent. En general, nos resultats sont un bon accord global avec les autres resultats. Nous trouvons aussi que la dependance de la section efficace totale sur le nombre d'electrons dans la cible et celle des pics de la section efficace de raies d'ionisation sur les parametres de la cible s'averent etre coherentes avec des observations anterieures. [Traduit par la Redaction], 1. Introduction Study on electron impact scattering and ionization of atoms and molecules is of fundamental interest, as they play a vital role in determining the chemistry of any environment [...]

The theoretical calculations of electron impact total ionization cross section for cycloalkane, aldehyde, and ketone group molecules are undertaken from ionization threshold to 2 keV. The present calculations are based on the spherical complex optical potential formalism and complex scattering potential ionization contribution method. The results of most of the targets studied compare fairly well with the recent measurements, wherever available and the cross sections for many targets are predicted for the first time. The correlation between the peak of ionization cross sections with number of target electrons and target parameters is also reported. It was found that the cross sections at their maximum depend linearly with the number of target electrons and with other target parameters, confirming the consistency of the values reported here. [ABSTRACT FROM AUTHOR]

The present article reports calculated elastic, differential, momentum transfer and excitation cross section for electron scattering from BF and BF2 radicals using the ab initio R-matrix method. The calculations are performed with complete active space—configuration interaction and static exchange models for both targets to yield scattering cross sections and resonance parameters. Elastic and momentum transfer cross sections are also calculated using the spherical complex optical potential method to cover a wide energy range. The total ionization cross section is also reported from ionization threshold to 5 keV. The calculated cross sections for these neutral species are important for BF3 plasma and are reported for the first time to the best of our knowledge except ionization. [ABSTRACT FROM AUTHOR]

The present article reports calculated elastic, differential, momentum transfer and excitation cross section for electron scattering from BF and BF2 radicals using the ab initio R-matrix method. The calculations are performed with complete active space—configuration interaction and static exchange models for both targets to yield scattering cross sections and resonance parameters. Elastic and momentum transfer cross sections are also calculated using the spherical complex optical potential method to cover a wide energy range. The total ionization cross section is also reported from ionization threshold to 5 keV. The calculated cross sections for these neutral species are important for BF3 plasma and are reported for the first time to the best of our knowledge except ionization. [ABSTRACT FROM AUTHOR]

We report the calculations of elastic (along with its symmetry components) and electronic excitation cross sections by electron impact of the three isomers of C4F6, namely, hexafluoro-1,3-butadiene (1,3-C4F6), hexafluoro-2-butyne (2-C4F6), and hexafluorocyclobutene (c-C4F6) belonging to the point groups C2, D3d, and C2v, respectively, using the R-matrix approach. The electron energy range is from 0.01 eV to 12 eV. We have employed the cc-pVTZ basis set for C and F atoms to generate self-consistent field molecular orbitals to construct the target states for all the isomers included in our calculations. All the target states are constructed by including correlation effects in a configuration interaction (CI) approach. The target properties such as vertical excitation energies and dipole moment of all the isomers are in reasonable agreement with the literature values. Differences in the cross sections of these isomers are strongly influenced by the effect of correlation and polarization effects and their geometrical extent. We have included the ground state and many excited states of each isomer in the trial wave function of the entire scattering system. The resulting elastic cross sections are compared with the available experimental results. The agreement is reasonably good for energies above 5 eV. The shape resonances detected at 2.57, 2.95, and 3.20 eV for c-C4F6, 1,3-C4F6, and 2-C4F6 isomers are associated with the negative anion formation of C3F3- as observed in the mass spectrometry experiments. We have also performed 1-state CI calculation for all the isomers that include only the correlated ground state. The position of resonances shifts to lower energies as the number of target states is increased compared to 1-state calculation for all the isomers. The elastic cross section for 2-C4F6 isomer is larger than the other isomers because of its larger spatial extent. The present cross section data are important for plasma simulation and modeling, especially related to fluorocarbon plasma. [ABSTRACT FROM AUTHOR]

An R-matrix formalism is used to study electron collision with the BF3 molecule using Quantemol- N, a computational system for electron molecule collisions which uses the molecular R-matrix method. Several target models are tested for BF3 in its equilibrium geometry, and the results are presented for the best model. Scattering calculations are then performed to yield resonance parameters, elastic, differential, excitation, and momentum transfer cross sections. The results for all the cross sections are compared with the experimental and theoretical data, and a good agreement is obtained. The resonances have been detected at 3.79 and 13.58 eV, with the ionization threshold being 15.7 eV. We have also estimated the absolute dissociative electron attachment (DEA) cross section for the F- ion production from BF3 , which is a maiden attempt. The peak of the DEA is at around 13.5 eV, which is well supported by the resonance detected at 13.58 eV. The cross sections reported here find a variety of applications in the plasma technology. [ABSTRACT FROM AUTHOR]

The total ionization cross section for CF ( x = 1 − 6) and CF ( x = 1 − 8) fluorocarbon species are studied with the Binary-Encounter Bethe (BEB) model using various orbital parameters calculated from restricted/unrestricted Hartree-Fock (RHF/UHF) and Density Functional Theory (DFT). All the targets were optimized for their minimal structures and energies with several ab-initio methods with the aug-cc-pVTZ basis set. Among them, the present results with RHF/UHF orbital energies showed good agreement with the experimental results for stable targets CF, CF, CF and CF. The results with the DFT ( ωB97X/ ωB97X-D) showed a reasonable agreement with the recent calculation of Bull et al. [J.N. Bull, M. Bart, C. Vallance, P.W. Harland, Phys. Rev. A 88, 062710 (2013)] for CF, CF and CF targets. The ionization cross section for CF, CF, CF, CF, CF, CF, CF, CF and CF were computed for the first time in the present study. We have also computed the vertical ionization potentials and polarizability for all the targets and compared them with other experimental and theoretical values. A good agreement is found between the present and the previous results. The calculated polarizability in turn is used to study the correlation with maximum ionization cross section and in general a good correlation is found among them, confirming the consistency and reliability of the present data. The cross section data reported in this article are very important for plasma modeling especially related to fluorocarbon plasmas. Graphical abstract: [ABSTRACT FROM AUTHOR]

We report here the total ionisation cross section for chlorofluoromethanes, namely CCl3F (Freon 11), CCl2F2(Freon 12), CClF3(Freon 13), CHCl2F (Freon 21), CHClF2(Freon 22), CH2ClF (Freon 31), CCl4and CClx(x= 1–3), radicals by electron impact from ionisation threshold to 2 keV. The total inelastic cross section is obtained employing a complex optical potential formalism and solving the Schrödinger equation through partial wave analysis. Using the complex scattering potential-ionisation contribution method, the total ionisation cross section is derived from the inelastic cross section for these targets. The results obtained are then compared with the existing experimental and theoretical data, wherever available. The present result shows reasonable agreement with previous data. For the CClxradicals, the ionisation cross section is predicted for the first time. The data reported here have immense interest to atmospheric and technological plasma modelling. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]