Cold Ion-Molecule Chemistry: The Very Different Reactions of He+ with CO and NO

The ion-molecule reactions He+ + CO → He C+ O and NO N+ have been measured at collision energies between 0 kB · 10 K. Strong variations of the rate coefficients are observed below 5 reaction decreases by ~30% whereas that increases a factor ~1.5. These observations interpreted in realm an adiabatic-channel capture model as arising from interactions ion charge dipole quadrupole moments NO. We show different low-energy behavior these originates closed- vs. open-shell electronic structures