Theory of ac Stark splitting in core-resonant Auger decay in strong x-ray fields

In this work we report the modification of the normal Auger line shape under the action of an intense x-ray radiation. Under strong Rabi-type coupling of the core, the Auger line profile develops into a doublet structure with an energy separation mainly determined by the relative strength of the Rabi coupling. In addition, we find that the charge resolved ion yields can be controlled by judicious choice of the x-ray frequency.

Figure 1

Schematic figure of the dominant channels involved in the interaction of neon with an x-ray field of frequency approximately 908.06 eV, chosen to match the Ne${}^{2+}(1s^{-1}–3p)$ transition energy.

Figure 2

Variation in the AES as the peak intensity of the pulse increases. The field has total duration about 48.8 fs ($\text{FWHM}=24.4$ fs) and the photon frequency chosen equal to 908.06 eV, while ${\Gamma }_{a^{\prime }}=0$. The inset label give the peak intensity values in units of W/cm${}^2$.

Figure 3

Ionization yields vs the peak intensity of the x-ray field. Field parameters as in Fig. 2 and ${\Gamma }_{a^{\prime }}=0.156$ eV. Solid curves refer to $\omega =908.06$ eV, while the dashed ones to $\omega =$ 904.06 eV.

Figure 4

Populations of the Ne${}^{2+}$ and Ne${}^{2+}(1s^{-1}–3p)$ states as a function of time peak intensity $I_0=5.0\times {10}^{17}$ W/cm${}^2$. All other parameters as in Fig. 3.