We have measured ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$${:}^9$Be isotope shifts in the ${}_{}{}^1{}_{}{}^{}\mathrm{S}$ and ${}_{}{}^1{}_{}{}^{}\mathrm{D}$ Rydberg series by resonance-ionization mass spectrometry. Pronounced interference of exchange and correlation contributions to the isotope shift is observed in the ${}_{}{}^1{}_{}{}^{}\mathrm{D}$ series, reflecting strong interaction of 2snd and 2pnp channels. The finite-mass correction to the ionization energy of ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ is inferred to be 270±40 MHz.

• Received 26 August 1987

DOI:https://doi.org/10.1103/PhysRevA.37.4207