Probing electron dynamics by ellipticity effects in molecular high harmonic generation

Two-centre interference in the recombination step of molecular high harmonic generation (HHG) has been observed in an aligned sample of CO2. Ellipticity dependent studies show clearly how the destructive interference can be 'switched off' by increasing the degree of ellipticity, thus shifting the effective resonance condition. The spectral dependence of the recombination interference was studied as a function of ellipticity effect and a model is proposed to explain these results. This model con. rms the important role of ellipticity on the HHG emission from an aligned molecular ensemble.