Precision Measurement of the Hydrogen-Deuterium1S−2SIsotope Shift

Abstract

Measuring the hydrogen-deuterium isotope shift via two-photon spectroscopy of the $1S-2S$ transition, we obtain 670 994 334 606(15) Hz. This is a 10-times improvement over the previous best measurement [A. Huber et al., Phys. Rev. Lett. 80, 468 (1998)] confirming its frequency value. A calculation of the difference of the mean square charge radii of deuterium and hydrogen results in $⟨r^2{⟩}_d-⟨r^2{⟩}_p=3.82007(65){\mathrm{fm}}^2$, a more than twofold improvement compared to the former value. DOI: http://dx.doi.org/10.1103/PhysRevLett.104.233001 © 2010 The American Physical Society