Angle-dependent high-order harmonic generation from a single N2 and O2 molecule

In this work we report a method to obtain the angular distribution of HHG from a single molecule, together with the accurate value of rotational temperature Tm of molecules and resulting definite distribution of molecular axes. In this method, no theoretical assumption is used. We employ an iterative procedure to retrieve the HHG distribution, based on two kinds of harmonic signals observed in the pump and probe experiment. One of them is the time-dependent signal produced from coherently rotating molecules under field-free conditions, and the other is the signal measured as a function of the relative angle between pump and probe polarizations at a fixed time delay.