Broadband near-ultraviolet dual comb spectroscopy

Abstract

The highly energetic photons of ultraviolet light drive electronic and rovibronic transitions in all molecular species. This radiation is thus a prime tool for strongly selective spectroscopic fingerprinting and real-time environmental monitoring if broad spectral coverage, short acquisition times, and high spectral resolution are achieved–requirements that are in mutual competition in traditional applications. As an approach with intrinsic potency in all three aspects, here we introduce ultraviolet dual comb spectroscopy using two broadband ultraviolet frequency combs centered at 871 THz and covering a spectral bandwidth of 35.7 THz. Within a 100 µs acquisition time window, we obtain rotational state-resolved absorption spectra of formaldehyde, a prototype molecule with high relevance for laser spectroscopy and environmental sciences. To our knowledge, this is the first realization of broadband dual comb spectroscopy in the ultraviolet spectral region and a pioneering tool to allow for real-time monitoring of rovibronic transitions.