Retrieval of interatomic separations of complex molecules by ultra-short laser pulses

In example of OSC, BrCN, O3 molecules, we show that the fitting method suggested in our previous work is applicable for retrieving interatomic separations of molecules with two structural parameters from high-order harmonics generated from these molecules in interaction with intense ultra-short infrared laser pulses. For linear molecules such as OSC, BrCN we find that the accurate structural information can be obtained using a small set of harmonics of only one alignment angle. However, for the planar molecule, O3, we need high harmonics of at least two alignment angles to retrieve two structural parameters of the molecule. We show that for both linear and planar molecules, the interatomic separations can also be retrieved from harmonics generated by isotropically oriented molecules. To develop the method, we also apply the genetic algorithm in the fitting procedure that really reduces time consuming compared to the direct scanning method.