Retrieval of molecular alignment and identification of multiple-orbital contribution by using polarized high harmonics from aligned N₂ molecules

With the parallel and perpendicular components of high harmonics generated by using aligned N₂ molecules, we propose a method to retrieve the alignment distribution induced by the aligning laser based on the quantitative rescattering theory. And the intensity of pump laser and gas temperature can be precisely determined as well. We find that the intensity ratio between two harmonic components is very sensitive to the inclusion of multiple-orbital contribution in the theory. We thus suggest that it could be used to identify the interference from inner orbitals by tuning input laser power or extending the spectral region of high harmonics.