On the binding of electrons to CS2: Possible role of quadrupole-bound states

Rydberg atoms are known to charge exchange with CS2 resulting in formation of CS2− ions that undergo rapid electric-field-induced detachment in applied fields ⪆1 kV cm−1. Here we examine a possible explanation for these observations based on the formation of ions in which the electron is weakly bound by the quadrupole moment (Q20 = + 3.3 au) of the neutral molecule. Theoretical calculations and further analysis of available experimental data suggest that such a mechanism might indeed account for the earlier observations. This is further supported to the observation that charge exchange does not occur in Rydberg atom collisions with COS (Q20 = −0.2 au).