vuv frequency-comb spectroscopy of atomic xenon

Direct frequency-comb spectroscopy of a single-photon transition (5p⁶-5p⁵6s) in ¹³²Xe is performed with a vacuum ultraviolet (vuv) frequency comb at 147 nm. The vuv comb is generated from an Yb-doped fiber laser system at a repetition rate of ∼79 MHz via high harmonic generation in a Kr gas jet placed at the focus point of an external enhancement cavity. For Doppler-reduced spectroscopy, a collimated atomic beam of isotope-selected ¹³²Xe is used as a target. Repeated measurements with different repetition frequencies and highly sensitive time-resolved detection allow us to determine the absolute transition frequency with an uncertainty of 140 MHz in the vuv region.