The Spectrum of Six-Times-Ionized Chromium, Cr VII

The spectrum of six-times-ionized chromium, Cr VII, has been observed from 90 Å to 2 000 Å by using a 5-m grazing-incidence spectrograph and a 3-m normal-incidence spectrograph. The light source was either an open vacuum spark or a vacuum sliding spark. About 135 lines have been identified as combinations between 60 levels in the configurations 3 s 2 3 p 6 , 3 s 2 3 p 5 3 d , 4 s , 4 p , 4 d , 4 f , 5 s , 5 d and 6 s as well as 3 s 3 p 6 3 d and 3 s 3 p 6 4 p . The energy parameters determined from least-squares fits of the observed level values are compared with Hartree-Fock calculations. The ionization energy, 3 s 2 3 p 5 2 P 3/2 -3 s 2 3 p 6 1 S 0 , is determined to 1 291 900 ± 600 cm -1 (160.17 ± 0.07 eV).