Comb-referenced Doppler-free spectrometry of the ${}^{200}$Hg and ${}^{202}$Hg intercombination line at 254 nm

Abstract

We report on precision spectroscopy of the 6s${}^2$ ${}^1$S${}_0\to$6s6p ${}^3$P${}_1$ intercombination line of mercury in the deep ultraviolet, by means of a frequency-comb referenced, wavelength-modulated, saturated absorption technique. This method allowed us to perform sub-Doppler investigations with an absolute frequency axis at 254 nm, while ensuring a relatively high signal-to-noise ratio. The absolute line center frequencies of the ${}^{200}$Hg and ${}^{202}$Hg bosonic isotopes were measured with a global uncertainty of 8 and 15 kHz (namely, 6.8$\times$10${}^{-12}$ and 1.3$\times$10${}^{-11}$, in relative terms), respectively, the statistical and systematic components being significantly reduced as compared to past determinations. This remarkable result was achieved also thanks to an in-depth study of the AC stark effect. Furthermore, we found the most accurate ${}^{200}$Hg-${}^{202}$Hg isotope shift ever obtained before, namely, $5295570\pm 15_{stat}\pm 8_{syst}$ kHz.

References in corpus (2)

• Doppler-free spectroscopy of the 1S0-3P0 optical clock transition in laser-cooled fermionic isotopes of neutral mercury
• Absorption line shape recovery beyond the detection bandwidth limit: application to the precision spectroscopic measurement of the Boltzmann constant