A calculation based on a relativistic distorted-wave approximation has been carried out for the electron impact excitation of the 3

Electron impact excitation of all the np 5 (n + 1)p J = 1, 2 and 3 states of argon (n = 3), krypton (n = 4) and xenon (n = 5) from the ground np 6 J = 0 state has been considered in the relativistic distorted-wave approximation. The differential and total cross sections are obtained for incident electrons in the energy range from 15 to 100 eV. The results are compared with the available experimental data and a few theoretical non-relativistic and semi-relativistic calculations wherever possible.

The R-matrix method, involving eight target states in the close-coupling formalism, is used to calculate elastic integral, differential and momentum transfer cross sections for electron impact on the formaldehyde molecule. We have also obtained the excitation cross sections for the seven lowest-lying electronically excited states which have symmetries 1 3A1, 1 1,3A2, 1 1,3B1 and 1 1,3B2. Their vertical excitation energies from the equilibrium geometry of the ground state X 1A1 lie in the range 3.58–9.99 eV. Configuration interaction (CI) wavefunctions are used to represent the target states. In our CI model, we keep the six core electrons frozen in doubly occupied molecular orbitals 1a1, 2a1 and 3a1. The complete active space consists of ten valence electrons that are allowed to move freely among the eight molecular orbitals: 4a1, 5a1, 6a1, 1b1, 2b1, 1b2, 2b2 and 3b2. In this CI model, we obtain good agreement of the dipole moment of the ground state with the experimental value, and a good representation of the vertical excitation spectrum of the excited states included in our calculation. We have also investigated the electron impact rotationally elastic and rotationally excitation transitions for the ground state for this asymmetric top molecule and obtained the rotationally resolved differential and integral cross sections for energies up to 20 eV. Our calculations do not detect any bound H2CO− states at the equilibrium geometry of the H2CO molecule. We find a shape resonance of the 2B1 symmetry with its resonance position at 1.32 eV and a corresponding resonance width of 0.546 eV at the equilibrium geometry of the molecule. This resonance provides a pathway for dissociative electron attachment when the CO bond is stretched beyond 3a0. Born correction is applied for the elastic and the dipole allowed transitions to account for higher partial waves excluded in the R-matrix calculation. We also compare R-matrix differential, partial, momentum transfer and excitation cross sections with the other work.

Noble gas-halogen complexes form the basis of possible excimer lasers. Electron collisions are investigated with the prototypical neon fluoride molecule as a function of internuclear separation. The study concentrates on the four states making up the excimer system: The low-lying X 2 ⌺ + and A 2 ⌸ repulsive states and the highlying 1 2 ⌺ + and 2 2 ⌸ charge-transfer states which can support bound states. These states are represented using a configuration-interaction expansion which is shown to yield accurate potential energy curves and target properties. Elastic and inelastic collision cross sections for the four states are calculated ab initio using the R-matrix method. Special care is needed to treat the large dipole moments found for the charge-transfer states which are predicted to have electron collision cross sections almost two orders of magnitude bigger than the lower states. Differential and momentum transfer cross sections are also considered for the electron impact on the repulsive ground state. Rate constants for electron deexcitation of the excimer states of NeF have been calculated for electron temperature corresponding up to 10 eV. The superelastic processes are dominated by the 1 2 ⌺ + → X 2 ⌺ + transition with thermal rate constant of ͑2-5͒ ϫ 10 −9 cm 3 s −1 in the entire range of electron temperature considered.

Relativistic distorted-wave (RDW) calculations are carried out for the electron impact excitation of the lowest autoionizing states np5(n+1)s2, 2P3/2,1/2 in Na(n = 2), K(n = 3), Rb(n = 4) and Cs(n = 5) alkali atoms from the ground np6(n+1)s, 2S1/2 state. Detailed results in the range of near threshold to 1.5 keV incident electron energies are obtained for total cross sections of the magnetic substates of the individual 2P3/2 and 2P1/2 states. Utilizing these, the results are presented for their total cross sections, alignment parameter 20 of the 2P3/2 state and the intensity of the ejected electrons from the 2P3/2 state. RDW calculations excluding the exchange effect and relativistic Born approximation calculations are also performed for comparison. The results are compared and discussed in the light of earlier available results and the recently reported experimental data from the Freiburg group (Germany).