ИСТИНА

Rotational streaking by a circularly polarized THz field of Auger electrons generated by a short extreme ultraviolet (XUV) or X-ray pulse is theoretically investigated. The streaking patterns, i.e. the energy and angular resolved Auger electron spectra, are calculated for different experimental conditions. The character of the streaking pattern depends on three main parameters: the duration of the XUV pulse, the Auger decay time-of-life and the period of the THz field. Different cases with various interrelations of these parameters are discussed. Examples of the patterns are calculated within the strong field approximation (SFA) [1]. Correspondence between the angular streaking of electrons [2,3], in the processes of photoionization and Auger ionization is considered. It is shown, that within SFA, calculation of the Auger electron spectra in THz rotational streaking is equivalent to the computation of the photoelectron spectra with some effective pulse, which includes also the retardation due to Auger decay depending on the Auger decay time. It is demonstrated that by studying the angular resolved Auger spectra one can obtain information about the Auger decay process directly in time domain, including the Auger lifetime and time-dependence of the decay probability. In the most interesting case when the Auger life-time and the FEL pulse duration are of the same order of magnitude, the Auger decay can be de-convoluted from the spectra by simultaneous measurement of the photoelectron spectra which provides information about the shape and duration of the ionizing XUV pulse. This information can then be used for the analysis of the Auger spectrum produced in the same shot.