The spectrum of doubly ionized xenon has been investigated. The study is based on photographic recordings of xenon spectra in the 490-8900 À range. The number o f classified lines has been increased from about 300 to about 1400. The lines have been classified as transitions between 73 even levels belonging to the 5s2 Sp4, S^Sp^ôp, 4/, 5 / and 5r°5/>6 configurations, and 83 odd levels belonging to the 5sSps, 5s15/r* 6s, 7s, 5d and 6d configurations. All the experimentally established Xe I I I levels are given in Tables I I and III. The level values were determined by a least-squares procedure in which the appropriately weighted wave numbers of the identified lines were used as input. All level designations are in LS notation. In most cases the names given to the levels were taken from least-squares fits of the theoretical energy expressions to the experimentally observed level values. In general, the calculated purities of the states
41Physica Scripta. Vol. 38, 347-369, 1988. A large number of strong xenon laser lines were reported some 20 years ago [9]. Primarily due to the work of the group in La Plata, the laser lines were classified as originating in doubly and trebly ionized xenon, but no further classifica tions were possible due to the lack of relevant spectroscopic data.In
W. P ersson, C . -G . W ahlstrôm , G . B ertuccelli, H . O. D i R o cco , J. G. R eyn a A lm an dos an d M . G allardoWhen performing the analysis of the experimental data we were guided by theoretical predictions of the level structures. Such predictions were obtained by diagonalization of the appropriate energy matrices, including C l matrix elements. The radial parts of the matrix elements were determined in Hartree-Fock calculations. Approximate scaling factors were determined from comparisons with calculations for similar structures. Figure 1 shows the relative positions and extensions of the configurations studied. The levels in 5s25p*, 5s5p5 and 5sP5p6 were known from earlier investigations, though the designation of one level, 5s5ps X P X has been revised. The 5s15pi n l configurations can be considered as being built on the ground configuration of Xe IV, 5s? 5p3, with the addition of an outer electron. The parent configur ation gives three terms, namely 4 S', 2D and 2P . Almost all levels of the 5s25pi 6p, 6s and 5d configurations have been experimentally established or verified in this work. In the 4/ configuration, five of the levels based on the 2P parent term are missing and in the 5s2 5p* 7s and configurations only levels based on the 4S and 2D parent terms have been located. In the 5/configuration, only the levels belonging to the lowest term, C S )SF, have been located with certainty. Figure 1 shows that there is severe overlapping of con figurations of the same parity. This leads to heavy mixing of states belonging to different configurations, even if the matrix elements connecting the states are small. Such mixing occurs between 6 5 and 5d, 7s and 6 d and between 6 p and 4/ states.
Even configurationsWhen interpreting...
