Satellite Lines in High-Energy Atomic Photoionization

The recent discovery that interchannel coupling persists to high energy [1] has altered the viewpoint that the non-relativistic photoionization cross section for an \textit{nl} atomic subshell at asymptotically high energies was essentially a single-electron process and depends upon energy E as E$^{-(l+7/2)}$ [2]. It was shown [3] that, owing to interchannel coupling, that this is correct only for photoionization \textit{ns} and \textit{np} states; for all \textit{nl} states with greater $l$, the asymptotic energy dependence is E$^{-9/2}$, just as it is for \textit{np} states. In the present work, implications of initial state correlation are explored. It is found that including initial state configuration interaction can have a profound effect upon the high-energy photoionization. For the photoionization of most \textit{nl} subshells ($l\ne $ 0) throughout the periodic system, the dominant transition is not the single-particle transition from the \textit{nl} subshell but a satellite transition of \textit{ns}$\to $\textit{kp} character. The cross section for the satellite transition exhibits the high-energy dependence characteristic of an $s$-state of E$^{-7/2}$, while the single-particle (main line) transition behaves as E$^{-9/2}$. Thus, in the nonrelativistic high-energy limit, most photoionization cross sections behave as E$^{-7/2}$, and satellite transitions dominate. Several examples are presented. This work was supported by DOE, NSF, and BSF. [1] E. W. B. Dias, \textit{et al}, Phys. Rev. Lett. \textbf{78}, 4553 (1997). [2] U. Fano and A. R. P. Rau, Phys. Rev. \textbf{162}, 68 (1967). [3] M. Ya. Amusia, \textit{et al}, Phys. Rev. Lett. \textbf{85}, 4703 (2000).