Knowledge Bank

Threshold Ion-Pair Production Spectroscopy (TIPPS) can determine field-free energetic thresholds for ion-pair $formationab$ in the same way that pulsed field ionization techniques (ZEKE/MATI) can obtain field-free ionization potentials. $H2$ and $D2$ were investigated and their ion-pair thresholds were determined to be $139714.8\pm 1.0cm-1$ and $140370\pm 1.0cm-1$, respectively. Pulsed field ion-pair formation mostly result from excitation of complex resonances between ion-pairs and electronic Rydberg states of the parent molecule. However, evidence of the direct excitation of ion-pair Rydberg states was also found.