High-harmonic generation spectroscopy is a promising tool for resolving electron dynamics and structure in atomic and molecular systems. This scheme, commonly described by the strong field approximation, requires a deep insight into the basic mechanism that leads to the harmonic generation. Recently, we have demonstrated the ability to resolve the first stage of the process - field induced tunnel ionization - by adding a weak perturbation to the strong fundamental field. Here we generalize this approach and show that the assumptions behind the strong field approximation are valid over a wide range of tunnel ionization conditions. Performing a systematic study - modifying the fundamental wavelength, intensity and atomic system - we observed a good agreement with quantum path analysis over a range of Keldysh parameters. The generality of this scheme opens new perspectives in high harmonics spectroscopy, holding the potential of probing large, complex molecular systems.
|כתב עת||Journal of Physics B: Atomic, Molecular and Optical Physics|
|מזהי עצם דיגיטלי (DOIs)|
|סטטוס פרסום||פורסם - 28 אוק׳ 2014|
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