Benchmarking accurate spectral phase retrieval of single attosecond pulses

A single XUV attosecond pulse or pulse train in the time domain is fully characterized if its spectral amplitude and phase are both determined. The spectral amplitude can be easily obtained from photoionization of simple atoms where accurate photoionization cross sections have been measured from, e.g., synchrotron radiations. To determine the spectral phase, at present the standard method is to carry out XUV photoionization in the presence of a dressing infrared (IR) laser.  In this talk we examine the accuracy of current phase retrieval methods where the dressing IR is relative weak such that photoelectron spectra can be accurately calculated by second-order perturbation theory. We suggest a general PRAB (Phase Retrieval of Attosecond Bursts) method which utilizes accurate one-photon and two-photon dipole transition matrix elements. We show that the PRAB method can in general retrieve accurate spectral phase compared to other simpler models that have been suggested.