Spin-rotation interaction in cold and ultracold collisions of N{sub 2}{sup +}({sup 2}{sigma}{sup +}) with {sup 3}He and {sup 4}He

In a recent work we compared spin-free collisions of N{sub 2}{sup +} with {sup 3}He and {sup 4}He using a newly developed potential energy surface. We found that such collisions exhibit a strong isotope effect in the ultracold regime. In the present study we consider the role of the spin-rotation interaction in cold He-N{sub 2}{sup +} collisions. We find that our spin-free vibrational quenching cross sections are not affected. Conversely, the cross sections for rotational quenching are strongly modified in the ultracold regime and exhibit resonance structures which are analyzed. These structures, which are not observed when the spin-rotation interaction is omitted, are shown to be due to the Feshbach resonances associated with the nonconservation of parity.