Optical isotope shifts in the 5702-Å line of Nd ii by collinear fast-beam-laser spectroscopy

Abstract

Optical isotope shifts in the 4${\mathit{f}}^{4}$5d $^{6}$${\mathit{K}}_{9/2}$--(23 537${)}_{9/2}^{0}$ transition (5702 \AA{}) of Nd ii have been measured using collinear fast-beam-laser spectroscopy. [The level notation (23 537${)}_{9/2}^{0}$ includes the term value of the level, its parity, and total angular momentum.] From the measured optical isotope shifts, changes in mean-square nuclear charge radii \ensuremath{\delta}〈${\mathit{r}}^{2}$〉 (${\mathrm{fm}}^{2}$) among the five even-even neodymium isotopes with mass numbers 142--150 have been deduced: (142,144), 0.283(9); (144,146), 0.257(8); (146,148), 0.284(9); and (148,150), 0.385(12). And configuration admixtures of the previously unclassified (23 537${)}_{9/2}^{0}$ level were quantitatively analyzed to be 4${\mathit{f}}^{4}$6p, 4${\mathit{f}}^{3}$5${\mathit{d}}^{2}$, and 4${\mathit{f}}^{3}$5d6s with mixing probabilities 15%, 84%, and 1%, respectively.