In 2006, Neufeld and co-workers reported the identification of the fluoromethylidynium cation, CF⁺, in the Orion bar, a photodissociation region (PDR). The observations were made with the IRAM 30-m and the APEX 12-m telescopes. CF⁺ is thought to be produced by the reaction of C⁺ with HF (identified in 1997). A second detection, in the Horsehead PDR, was reported by Guzmán et al. in 2012. They suggested that CF⁺ can be used as a tracer of C⁺. CF⁺ has recently been detected by Liszt et al. in diffuse, translucent, and spiral arm clouds.