We exploit the relationship between high harmonic generation (HHG) and the molecular photorecombination dipole to extract the molecular-frame differential photoionization cross section (PICS) in the extreme ultraviolet (XUV) for molecular nitrogen. A shape resonance and a Cooper-type minimum are reflected in the pump-probe time delay measurements of different harmonic orders, where high-order rotational revivals are observed in N₂. We observe the energy- and angle-dependent Cooper minimum and shape resonance directly in the laboratory-frame HHG yield by achieving a high degree of alignment, [SEE FORMULA IN ABSTRACT cos2 θ] 0.8. The interplay between PICS and rotational revivals is confirmed by simulations using the quantitative rescattering theory. Our method of extracting molecular-frame structural information points the way to similar measurements in more complex molecules.
X. Ren et al., "Measuring the Angle-Dependent Photoionization Cross Section of Nitrogen using High-Harmonic Generation," Physical Review A - Atomic, Molecular, and Optical Physics, vol. 88, no. 4, American Physical Society (APS), Oct 2013.
The definitive version is available at https://doi.org/10.1103/PhysRevA.88.043421
Keywords and Phrases
Degree Of Alignments; Extreme Ultraviolets; Harmonic Orders; High Harmonic Generation; Molecular Nitrogen; Photoionization Cross Section; Photorecombination; Pump-Probe Time Delay, Electron Resonance; Nitrogen; Photoionization, Harmonic Generation
International Standard Serial Number (ISSN)
Article - Journal
© 2013 American Physical Society (APS), All rights reserved.
01 Oct 2013