Hyperfine structure in the 5 d 9 6 p and 5 d 8 6 s 2 configurations of the spectrum of Hg III

Abstract

In most of the lines 5 d 9 6 p –5 d 8 6 8 2 the components due to 200 Hg, 202 Hg and 204 Hg have been resolved and term isotope shifts have been assigned for these isotopes for nearly all the terms of each configuration. Some less accurate data for 198 Hg, 199 Hg and 201 Hg are obtained from measurements on incompletely resolved components. An approximate magnetic hfs analysis for all terms of 5 d 9 6 p and 5 d 8 6 8 2 has been made for 199 Hg. This analysis was made on the assumption that components of even isotopes always preserve the same relative spacing. The assumption does not appear to be strictly valid in a few cases, the largest departure apparently occurring in lines measured by Mrozowski (1942) involving the 5 d 8 ½ ½ 6 8 2 | 0 term (and possibly in two other lines). The magnetic hfs is compared with that expected for jj -coupling, and it conforms moderately well, but there is evidence of intermediate coupling effects in both configurations, especially 5 d 9 6 p , and in one term at least of this configuration there is also indication of a small perturbation from 5 d 8 6 8 6 p . By deducing the nuclear magnetic moment of 199 Hg the results are shown to be tolerably consistent with previous investigations. The isotopic structures are very regular compared with those reported for the isoelectronic Pt I spectrum. Such small irregularities as have been found are discussed; those found in 5 d 8 6 8 2 do not seem to be due to the nuclear ‘volume’ effect.