Rotational cross sections and rate coefficients fore-CO ande-HCN collisions under interstellar conditions

Abstract

Rotational cross sections and rate coefficients for e-CO and e-HCN collisions have been calculated in the energy range relevant to dark interstellar clouds by using the close-coupling method. Gordon's technique has been used for solving the coupled Schrodinger equations. Initial rotational levels j = 0, 1, and 2 of CO and HCN have been considered. The rotational cross sections have been calculated in the energy range 0.0006 to 0.1 eV and the rate coefficients in the temperature range 5-100 K. The cross sections and rate coefficients thus obtained have been compared with Born and unitarized time-dependent perturbation calculations.

Electron-impact rotational and hyperfine excitation of HCN, HNC, DCN and DNC

“…In Fig. 2, we compare our integral cross‐sections with those of Jain & Norcross (1985) and Saha et al (1981). Excellent agreement is observed down to 0.01 eV.…”

“… Integral cross‐sections for rotationally inelastic scattering of electrons by HCN as a function of electron energy. The lozenges and stars denote the results of Saha et al (1981) and Jain & Norcross (1985), respectively. The present calculations are given by the solid thick lines.…”

“…A theoretical determination of rotational cross‐sections and rate coefficients for e–HCN was carried out by Saha et al (1981) for the rotationally inelastic transitions J = 0 → 1, J = 1 → 2 and J = 0 → 2. Cross‐sections were computed using the rotational close‐coupling method and rate coefficients were obtained in the temperature range 5–100 K. An additional study includes that of Jain & Norcross (1985), where the adiabatic‐nuclei‐rotation (ANR) approximation was combined with model potentials.…”

“…Cross‐sections were computed using the rotational close‐coupling method and rate coefficients were obtained in the temperature range 5–100 K. An additional study includes that of Jain & Norcross (1985), where the adiabatic‐nuclei‐rotation (ANR) approximation was combined with model potentials. The cross‐sections were computed for the same set of transitions as in Saha et al (1981). In addition to electron scattering, the rotational excitation of HCN by He as a substitute for H 2 has been studied by Green & Thaddeus (1974), Green (unpublished data) 1 and Monteiro & Stutzki (1986) (see also references therein).…”

Slow-electron collisions with CO molecules in an exact-exchange plus parameter-free polarization model

“…16 we have plotted our total cross sections for the dipole (0~1 and 1~2) and quadrupole (0~2) al- There are significant differences between our ESEP results and the SMEP calculations of Saha et al. [32]. The calculations of Saha used a simple repulsive wall for the inner region, and were carried out in the laboratory frame, as were those of Crawford and Dalgarno [24] and Chandra [30].…”