Matthias Germann

We describe how the annihilation of antiprotons can be utilized to generate highly charged isomeric ions in an ion-trap setup. We identify optical transitions in the hyperfine splitting of Hydrogen-like atoms composed of an isomer and a single electron in the ground state. We identify promising candidates in the isomers of Y, Nb, Rh, In, and Sb, for which the hyperfine transition lies in the infrared and whose excited state level lifetime is in the hundreds of milliseconds, which is suitable for metrology applications.

State-selected Coulomb-crystallized molecular ions were employed for the first time in ion-molecule reaction studies using the prototypical charge-transfer process $\mathrm{N_2^++N_2\rightarrow N_2+N_2^+}$ as an example. By preparing the reactant ions in a well-defined rovibrational state and localizing them in space by sympathetic cooling to millikelvin temperatures in an ion trap, state- and energy-controlled reaction experiments with sensitivities on the level of single ions were performed. The experimental results were interpreted with quasi-classical trajectory simulations on a six-dimensional potential-energy surface which provided detailed insight into translation-to-rotation energy transfer occurring during charge transfer between N$_2$ and N$_2^+$.