R-matrix calculations of low-energy electron alkane collisions

Varambhia, Hemal N.; Munro, James J.; Tennyson, Jonathan

doi:10.1016/j.ijms.2007.12.002

Cited by 22 publications

(29 citation statements)

References 100 publications

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“…In the bottom panel of Figure 1, we compare our results using 10 states in cc-pVDZ basis with the previous Rmatrix calculations of Nestman et al, 35 Varambhia et al, 36 and Vinodkumar et al, 37 and with the experiments. We find that our elastic cross sections agree reasonably with both the experimental and theoretical results.…”

Section: A Elastic Scatteringmentioning

confidence: 65%

“…were found sufficient in all cases. In our model for the inner region, we use complete active space configuration interaction (CASCI) (full CI in the excitation space restricted to lowest lying virtual orbitals), wave functions that was successfully used in similar problems 36,37,50 previously. In our calculations, we use a CASCI (8,8) model based on Hartree-Fock orbitals.…”

Section: Methods Of Calculationmentioning

confidence: 99%

“…In the top panel, we present the representative examples of previous experimental and theoretical studies of elastic electron−methane scattering, including the experimental results of Ferch et al, 6 Lohmann and Buckman, 13 Boesten and Tanaka, 1 Bundschu et al, 60 Shyn and Cravens, 17 Sohn et al, 61 and Tanaka et al, 62 as well as theoretical calculations using the variational Schwinger method by Iga et al 10 and Machado et al, 63 and the results of R-matrix calculations by Nestmann et al, 35 Varambhia et al, 36 and Vinodkumar et al 37 We also show the recommended values for the elastic cross sections by Fuss et al 42 In the middle panel, our R-matrix elastic cross sections can be seen for the equilibrium structure of methane. We compare the results for cc-pVDZ, cc-pVTZ, 6-31G(d), and 6-311G(d) bases for the target using 10 states (24 CI roots for cc-pVDZ and 23 for other bases) in the calculations.…”

Section: A Elastic Scatteringmentioning

confidence: 99%

“…Methane is the primary hydrocarbon of interest in electron-induced fragmentation processes, both because of its intrinsic importance and because it serves as a model of more complex hydrocarbons. Numerous experimental and theoretical [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] studies have addressed methane-electron collisions. Most of these focused on elastic processes, reporting total 3, 6, 7, 11-16, 19, 29, 32, 33, 37 and elastic 1, 2, 4, 10, 15-17, 29, 30, 32, 33, 36 cross sections, so, the understanding of inelastic processes is far from complete.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the electron-impact dissociation of methane

Ziółkowski

Vikár

Mayes

et al. 2012

The Journal of Chemical Physics

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The product yield of the electron-impact dissociation of methane has been studied with a combination of three theoretical methods: R-matrix theory to determine the electronically inelastic collisional excitation cross sections, high-level electronic structure methods to determine excited states energies and derivative couplings, and trajectory surface hopping (TSH) calculations to determine branching in the dissociation of the methane excited states to give CH(3), CH(2), and CH. The calculations involve the lowest 24 excited-state potential surfaces of methane, up to the ionization energy. According to the R-matrix calculations, electron impact preferentially produces triplet excited states, especially for electron kinetic energies close to the dissociation threshold. The potential surfaces of excited states are characterized by numerous avoided and real crossings such that the TSH calculations show rapid cascading down to the lowest excited singlet or triplet states, and then slower the dissociation of these lowest states. Product branching for electron-impact dissociation was therefore estimated by combining the electron-impact excitation cross sections with TSH product branching ratios that were obtained from the lowest singlet and triplet states, with the singlet dissociation giving a comparable formation of CH(2) and CH(3) while triplet dissociation gives CH(3) exclusively. The overall branching in electron-impact dissociation is dominated by CH(3) over CH(2). A small branching yield for CH is also predicted.

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Section: A Elastic Scatteringmentioning

confidence: 65%

Section: Methods Of Calculationmentioning

confidence: 99%

Section: A Elastic Scatteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling the electron-impact dissociation of methane

Ziółkowski

Vikár

Mayes

et al. 2012

The Journal of Chemical Physics

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“…For the theoretical approach, methane is one of the most intensively studied molecules [16][17][18][19][20][21][22][23][24][25][26][27][28]. The high value of dipole polarizability makes it difficult to determine theoretically the low energy elastic collisions parameters.…”

Section: Introductionmentioning

confidence: 99%

Ramsauer-Townsend minimum in methane — modified effective range analysis

Fedus

Karwasz

2014

Eur. Phys. J. D

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Abstract. Electron-scattering cross sections in methane are analysed in the very-low energy region. The correspondence between integral elastic, elastic differential and momentum transfer cross sections is checked via a novel approach to modified effective range theory, in order to determine the depth and position of the Ramsauer-Townsend minimum. Phase shifts of the two lowest partial waves are obtained explicitly and parameterized by four coefficients with the physical meaning of the scattering lengths and the effective ranges. Using recent experiments on vibrational cross sections performed over an extended (0-180• ) angular range and comparing several theories, an agreement within 10% has been obtained between experimental total and present summed (elastic + vibrational) cross sections in the whole 0.1-2.0 eV energy range. An additional check for consistency is done using two-term Boltzmann analysis to derive electron diffusion coefficients. Calculated drift velocities and transversal diffusion coefficients at 0-10 Td reduced electric field agree within 5% with experiments.

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Current literature in mass spectrometry

2008

J. Mass Spectrom.

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In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Reviews; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (4 Weeks journals ‐ Search completed at 25th. June 2008)

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R-matrix calculations of low-energy electron alkane collisions

Cited by 22 publications

References 100 publications

Modeling the electron-impact dissociation of methane

Modeling the electron-impact dissociation of methane

Ramsauer-Townsend minimum in methane — modified effective range analysis

Current literature in mass spectrometry

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