Electron-nucleus interactions in few-electron Fe ions

Measurements have been made of the total decay rates of the 14.4-keV level in the Fe-57 nucleus in highly charged Fe ions having one to six electrons outside the nucleus. Results are 10.0(9), 7.06(18), 7.36(14), 7.16(11), 7.10(23), 7.28(25), and 6.92(46), in units of 10(6) s-1, for ions of charge states q from 25 to 19, respectively. For the q = 25 single-electron ion the result quoted is for the ion in which the spin of the 1s1/2 electron and the excited nuclear state are coupled to give quantum number F = 1. Measurements have also been made of the K-shell fluorescent yields for ions in charge states q (before K-vacancy production) from 22 to 19. Results are 0.62(1), 0.50(1), 0.48(2), and 0.50(6), respectively. These data are discussed and compared with theoretical predictions.