Estimation of the specific mass effect in the isotope shifts of energy levels in the optical spectrum of Ba I and Ba II

Abstract

A graphical method for separating mass and volume effects from purely optical isotope shift data is presented and compared with King's "bunching" method. Recent experimental data on isotope shifts for a wide range of spectral lines in the naturally abundant isotopes of BaI and BaII are analysed. Some agreement is found with muonic x-ray data concerning the nuclear size for the isotopes 136, 137 and 138, but there is disagreement (over 20 %) for the other isotopes. The level isotope shifts are further parameterised in terms of a linear model, and the specific mass effect is decomposed into sums of one-electron and two-electron shift parameters with respect to the inert-gas like ground state of Ba III.

Isotope shifts and hyperfine structure of134-138Ba II by fast ion beam-laser spectroscopy

“…6 i . s ~~ (585 nm) = -158 MHz, which is about -5 times the NMS and consistent with Wilson (1978) and Pendrill (1984).…”

“…Wilson (1978) has calculated the SMS for 5d+6p to be -7ZAA MHz which gives -144 MHz for the isotope 'j6Ba with respect to "'Ba, whereas Pendrill (1984) used semi-empirical estimates by a graphical method to obtain -152( 14) M H z for the SMS. The SMS for the 6s+6p transition is expected to be small (Aufmuth era/ 1987) so if we assume that it is zero in -K455F585/F45s) = -1483.0(1.4) GI-Iz amu we can derive the SMS for the d-p transitions, e.g.…”

Hyperfine structure and isotope shift of the neutron-rich barium isotopes139?146Ba and148Ba

“…The experimental value of D is much smaller than the normal mass shift constants and thus agrees with the standard assumption for the specific mass shift parameters for s-p and s2-sp transitions [14], which corresponds to D= -108(470) GHz amu. From an abinitio calculation Pendrill estimated the specific mass shift of the atomic line to be lS5531< 100 GHz amu [18] in agreement with the results from King plots with muonic x-ray data [19,20] which give $553 ~ -240(140) GHz ainu.…”

Evaluation of the specific mass shift and field shift in the alkaline-earth Sr atom

“…The interpretation of the RIS will throw light on nuclear properties (such as size and shape) only after correlation effects, due to the two-particle operator representing the SMS, have been accounted for. In the last few years, with the development of high resolution laser spectroscopy, extensive experimental investigations of alkaline-earth atoms have been carried out ([, [1][2][3][4][5]). Efforts on the theoretical side have been directed mainly toward the calculation of the FS, but lately a few calculations have been carried out of the SMS for two-electron systems ([-4], [,6], [7]).…”