Low and intermediate energy electron collisions with the C2−_2^- molecular anion

Calculations are presented which use the molecular R-matrix with pseudo-states (MRMPS) method to treat electron impact electron detachment and electronic excitation of the carbon dimer anion. Resonances are found above the ionisation threshold of C$_2^-$ with $^1\Sigma^+_g$, $^1\Pi_g$ and $^3\Pi_g$ symmetry. These are shape resonances trapped by the effect of an attractive polarisation potential competing with a repulsive Coulomb interaction. The $\Pi_g$ resonances are found to give structure in the detachment cross section similar to that observed experimentally. Both excitation and detachment cross sections are found to be dominated by large impact parameter collisions whose contribution is modelled using the Born approximation.Comment: 18 pages, 5 figures constructed from 8 file

QDB: A new database of plasma chemistries and reactions

One of the most challenging and recurring problems when modeling plasmas is the lack of data on the key atomic and molecular reactions that drive plasma processes. Even when there are data for some reactions, complete and validated datasets of chemistries are rarely available. This hinders research on plasma processes and curbs development of industrial applications. The QDB project aims to address this problem by providing a platform for provision, exchange, and validation of chemistry datasets. A new data model developed for QDB is presented. QDB collates published data on both electron scattering and heavy-particle reactions. These data are formed into reaction sets, which are then validated against experimental data where possible. This process produces both complete chemistry sets and identifies key reactions that are currently unreported in the literature. Gaps in the datasets can be filled using established theoretical methods. Initial validated chemistry sets for SF 6 /CF 4 /O 2 and SF 6 /CF 4 /N 2 /H 2 are presented as examples

Low-energy electron collisions with C2 using the R-matrix method

Calculations are presented for the bound and continuum states of the C[?]2 system using the polyatomic version of the UK molecular R-matrix code. The calculations, based on a 26-state close-coupling expansion, show the presence of three bound doublet states of C[?]2 and a quartet state that only becomes bound at large internuclear separation. A number of resonance states are found and their behaviour as a function of the C2 bond length is studied. Cross sections for electron impact electronic excitation are presented with particular emphasis on excitation of the d 3Pg state which is responsible for the well-known Swan emission bands

Electron-molecule collisions at low and intermediate energies using the R-matrix method

We present the latest developments of the R-matrix method as applied to electron-molecule collisions. A variety of calculations for H2O are presented including the study of rotational excitation and preliminary data for dissociative electron attachment. Results for the application of the recently developed molecular R-matrix with pseudostates (MRMPS) method to neutral and cationic targets are also included. This method is currently being applied to the study of collisions with anionic targets