Isotope Shift in the First Three Spectra of Boron

Isotope shifts have been observed in the first three spectra of boron, with separated isotopes. On the assumption that the total observed shift consists only of the (exactly calculable) normal mass effect and a specific mass effect, the results are as follows (a positive sign indicating a shift of ${\mathrm{B}}^{11}$ toward the violet relative to ${\mathrm{B}}^{10}$): where the calculated specific shift, $\Delta {\sigma }_{s,\mathrm{calc}}$ is based on hydrogen-like wave functions of the Hughes-Eckart type.