Probing molecular structure with alignment-dependent high-order harmonic generation

High-order harmonic generation (HHG) from nonadiabatically aligned molecules has been demonstrated to have new abilities to probe molecular dynamics and structures with femtosecond (fs) temporal resolutions [1–4]. In the recent study of HHG from coherently rotating molecules, the present authors have shown that HHG properties strongly depend on the degree of molecular alignment, and a low rotational temperature T
rot
and resulting high degree of alignment is strongly desired in the HHG experiment to retrieve the image of electronic distribution or orbital structure in a molecule [3].