First Astronomical Detection of the CF + Ion

We report the first astronomical detection of the CF^+ (fluoromethylidynium) ion, obtained by recent observations of its J = 1-0 (102.6 GHz), J = 2-1 (205.2 GHz), and J = 3-2 (307.7 GHz) pure rotational emissions toward the Orion Bar. Our search for CF^+ - carried out using the IRAM 30m and APEX 12m telescopes-was motivated by recent theoretical models that predict CF^+ abundances of a few × 10^{-10} in UV-irradiated molecular regions where C^+ is present. The measurements confirm the predictions. They provide support for our current theories of interstellar fluorine chemistry, which suggest that hydrogen fluoride should be ubiquitous in interstellar gas clouds.