Comparison of high harmonic conversion efficiency in atomic and diatomic molecular gases

Abstract
High harmonic conversion efficiency has been experimentally compared in the atomic gas Ar and the diatomic molecular gases O2 and N2. It is shown that, in the saturation region, if the atomic and diatomic molecular gases have similar polarizabilities, the one with the higher ionization potential has the higher harmonic efficiency. If the atomic and molecular gases have similar polarizabilities and ionization potentials, the atomic gas will have a higher harmonic efficiency than the molecular one.