Inner-shell photoionization in an excited atom: Many-electron effects and partial cross sections in 2p^{6}3p ^{2}P_{3/2} sodium atoms

Using synchrotron radiation, we have investigated, over an extended photon energy range, the full photoelectron spectrum following ionization in the 2p subshell of Na atoms laser excited into the 2${\mathit{p}}^6$3${\mathit{p}}^2$ ${\mathit{P}}_{3/2}$ state. We have determined the relative cross sections for leaving the positive ions in various final states, corresponding to the main line and the satellite lines. In particular, we have observed a strong enhancement of the relative intensity of the shakeup satellites in the excited atom. Our measurements allow testing of the validity of a many-body calculation of the 2p-photoionization cross section.