A new method for accurate retrieval of atomic dipole phase or photoionization group delay in attosecond photoelectron streaking experiments

Abstract

In recent years, attosecond streaking experiments have been used to extract the phase of photoionization dipole transition matrix element (or the photoionization group delay) in atoms, molecules and condensed materials. The most accurate retrieval method so far is based on the frequency-resolved optical gating for complete reconstruction of attosecond bursts (FROG-CRAB). However, the FROG-CRAB employs a number of approximations that would cause errors in the retrieved results. In this article, we applied our recently proposed attosecond pulse characterization method phase retrieval of broadband pulses (PROBP) to the retrieval of photoionization group delay difference between Ne() and Ne() ionization channels, and between Ar() and Ne() channels. Our simulations demonstrate that more accurate results can be retrieved using PROBP than using FROG-CRAB, and cast doubts on group delays reported in previous streaking measurements.