Enhancements of rescattered electron yields in above-threshold ionization of molecules

In above-threshold ionization of rare-gas atoms, photoelectron spectra recorded in the 10(13)-10(14) W cm(-2) range exhibit enhancements in the rescattering plateaus that do not have a unified theoretical interpretation yet. Here an experimental search for such enhancements is reported in simple molecules with ionization potentials near those of rare-gas atoms such as H-2 and N-2 for argon and O-2 for xenon, and in other molecules such as CO2 and N2O. Only H-2 exhibits the enhancements previously observed in atoms. The H-2 particularity is interpreted in terms of its simpler ion structure and associated ionization paths compared with other molecules.