New Method for the Study of Dissociation Dynamics of State-Selected Doubly Charged Ions: Application to ${\mathrm{CO}}^{2+}$

A new technique is described which is capable of observing the stability of specific states of doubly charged molecular ions with vibrational level resolution. The method is based on the process of double photoionization using synchrotron radiation. Pairs of threshold electrons identify the initial state, and the resulting ions are characterized by their times of flight. Lifetimes have been measured for specific levels of ${\mathrm{CO}}^{2+}$ and confirm, except for the very lowest levels, the intrinsic instability of this species on the $\mu \mathrm{s}$ time scale.