title: Frequency comb velocity-modulation spectroscopy.
abstract: We have demonstrated a new technique that provides massively parallel comb spectroscopy sensitive specifically to ions through the combination of cavity-enhanced direct frequency comb spectroscopy with velocity-modulation spectroscopy. Using this novel system, we have measured electronic transitions of HfF⁺ and achieved a fractional absorption sensitivity of 3×10⁻⁷ recorded over 1500 simultaneous channels spanning 150  cm⁻¹ around 800 nm with an absolute frequency accuracy of 30 MHz (0.001  cm⁻¹). A fully sampled spectrum consisting of interleaved measurements is acquired in 30 min.
authors.affiliation: JILA, National Institute of Standards and Technology and University of Colorado Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA. sinclail@jila.colorado.edu
authors.forename: Laura C
authors.initials: LC
authors.lastname: Sinclair
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Cossel
authors.forename: Tyler
authors.initials: T
authors.lastname: Coffey
authors.forename: Jun
authors.initials: J
authors.lastname: Ye
authors.forename: Eric A
authors.initials: EA
authors.lastname: Cornell