National Research Council of Canada. NRC Steacie Institute for Molecular Sciences
Based on the sudden perturbation approximation and sequential three-stage model of laser-assisted x-ray photoionization, we refine the theory of attosecond streak camera and spectral phase interferometry. We formulate a simple and transparent analytical quantum theory of attosecond photoelectron interference in the separable Coulomb–Volkov continuum, with both Coulomb and laser fields treated non-perturbatively. The theory is applicable for arbitrary laser-field polarization and x-ray pulse parameters (polarization, chirp, pulse duration and delay time between replicas). We analyse in detail the main features of photoelectron spectra and analytical approach to multicentre molecular continuum. Due to an interplay between a number of sequential and non-sequential temporal and spatial interference mechanisms, the shapes and positions of photoelectron peaks are strongly dependent on the relative orientation of field polarization directions, molecular orientation and other parameters of the x-ray and laser fields. The theory provides a basis for experimental characterization of both fields, as well as their relative phase.
Journal of Physics B: Atomic, Molecular and Optical Physics41, no. 4 (12 February 2008).