Absolute total dissociation cross sections for electron impact, σt,diss, from 8 to 700 eV are reported for C2F6. A dense set of data was obtained in the technologically important 8–30 eV energy range relevant to modelling the type of plasmas used in both fundamental and applied scientific investigations. The threshold for dissociation was found to be 12.0 ± 0.2 eV and appears to be associated w...

The spectra ofthe diketone compounds biacetyl, acetylacetone, acetonylacetone, 1,2cyclohexanedione, and 1,4-cyclohexanedione have been investigated by the technique oflowenergy variable-angle electron energy-loss spectroscopy. With this method low-lying, spinforbidden transitions have been observed. The energy difference between the lowest spin-allowed and spin-forbidden n-+ 1r* excitations in ...

Theory and experiment are compared for the electron-impact double ionization of Mg. Direct ionization cross sections, involving the simultaneous ionization of both 3s electrons, are calculated using a non-perturbative time-dependent close-coupling method. Indirect ionization cross sections, involving the ionization of either a 2p or 2s electron followed by autoionization, are calculated using a...

Electron-molecule collisions play a crucial role in astrophysical environments where the electron fraction is higher than about 10−5, e.g. in the diffuse ISM, PDRs or comets. We present here a brief review of our recent R-matrix calculations of rate coefficients for electron-impact rotational excitation of interstellar molecules. Our major result is the prediction of emission lines from higher ...

Time-dependent close-coupling and time-independent distorted-wave methods are used to calculate the electron-impact double-ionization cross section for the 1s22s2 ground configuration of the B+ atomic ion. The direct double-ionization cross section is calculated using the non-perturbative close-coupling method between the direct double-ionization threshold of 63.1 eV and the 1s ionization thres...

In a partially ionized hypersonic flow field, electron collision plays a significant role in energy re-distribution and in the production of excited states of atoms and molecules that can subsequently radiate. Thus electron collision data is part of the database used in modelling high speed entry flows. First principles computational methods for the calculation of electron-impact data are revie...

Electron-impact double ionization from the valence shell of neon has been measured at an incident electron energy of 3662.5 eV. Double-coincidence (e, (3-1)e) measurements have been made between the scattered electron and each of the ejected electrons in turn, ejected energies were 10 eV and 90 eV, respectively, at ejection angles of 45, 60, 90, 120 and 135 degrees with respect to the incident ...

Variable and potential plasma applications in aerospace engineering are exemplified by ion thrusters, flow control by plasma actuator, enhanced ignition and combustion stability. The operational environments span a range from the rarefied to continuum gasdynamic regimes; however, the ionization process in practical applications is mostly by electron impact. The fundamental ionization mechanisms...

Low-energy electron impact excitations of S2 molecules are studied using the fixedbond R-matrix method based on state-averaged complete active space SCF orbitals. Integral cross sections are calculated for elastic electron collision as well as impact excitation of the 7 lowest excited electronic states. Also, differential cross sections are obtained for elastic collision and excitation of the a...

Rotational excitation of H2O, HDO and D2O by thermal electron impact is studied using the molecular R-matrix method. Rate coefficients are obtained up to electron temperatures of 8000 K. De-excitation rates and critical electron densities are also given. It is shown that the dominant transitions are those for which J = 0, ±1, as predicted by the dipolar Born approximation. However, a pure Born ...