Quantum Coherence in the Time-Resolved Auger Measurement

We present a quantum mechanical model of the attosecond-XUV (extreme ultraviolet) pump and laser probe measurement of an Auger decay [Drescher et al., Nature (London) 419, 803 (2002)] and investigate effects of quantum coherence. The time-dependent Schrödinger equation is solved by numerical integration and in analytic form. We explain the transition from a quasiclassical energy shift of the spectrum to the formation of sidebands and the enhancement of high- and low-energy tails of the Auger spectrum due to quantum coherence between photoionization and Auger decay.

Figure 1

Scheme of the Auger pump-probe measurement

Figure 2

Streaked Auger electron spectra for different Auger life times ${\tau }_A$. XUV-laser delay times are $\Delta t=0$ (solid lines) and $\pi /\omega$ (dashed). Spectra for XUV pulse duration of ${\tau }_x=300\mathrm{a}\mathrm{s}$ (lower dotted lines) and $700\mathrm{a}\mathrm{s}$ (upper dotted lines) nearly coincide with spectra for 500 as.

Figure 3

Auger electron spectrum for a 500 as pulse and 500 as Auger life time. The full model (solid line) coincides with the spectrum using Eq. (18) within the resolution of the plot. The ad hoc formula used in Ref. 4 (dot-dashed) produces a narrower spectrum. The curves are normalized to have equal integral.