Single- and double-electron capture processes in low-energy collisions of N3+ with He

Single-electron capture (SEC) and double-electron capture (DEC) processes in collisions of ground state N3+ (2s21S) ions with He are investigated by using the quantum-mechanical molecular-orbital close-coupling (QMOCC) method. The ab initio adiabatic potentials, radial and rotational coupling matrices utilized in QMOCC calculations, are obtained from the multireference single- and double-excitation configuration interaction approach. Total and state-selective SEC and DEC cross sections are presented in the low-energy range from 0.1 eV to 15 keV (i.e., 0.007 eV/u -1.07 keV/u) and rate coefficients in the temperature range from 104 to 107 K. Our results indicate that the SEC dominates the charge-transfer process in the considered energy region of this collision system and the SEC cross sections are nearly constant in the relatively high-collision energy region, while the DEC cross sections are about 2 orders of magnitude smaller. It is found that, for the SEC processes, in the dominant mechanisms, electrons are captured to exoergic channels N2+ (2s2p22D,2S), and for the DEC processes, they are captured to N+ (2s22p21D,1S). Our calculations also reveal that rotational couplings become important at E > 10 eV/u for SEC and E > 200 eV/u for DEC processes.