Strong-field enhanced ionization of molecules*

Enhanced ionization (EI) of molecules has been extensively studied over the past two decades as a common process in molecular dissociative ionization in strong laser fields. However, experimental study of EI is far from being complete. In this work, we perform a systematic experimental investigation of EI in several commonly-studied small molecules, including N2, O2, and CO. Our results show that double-ionization induced EI occurs only in a newly-discovered channel with a lower kinetic energy release instead of the commonly-seen channel. Furthermore, the dependence of EI on laser intensity and laser polarization is explored. Lastly, the comparison between N2 and O2 shows that molecular orbital shape plays a key role in EI.