Fluoroform\n(CHF<sub>3</sub>) Production from CF<sub>3</sub>CHO Photolysis and\nImplications for the Decomposition of Hydrofluoroolefins\nand Hydrochlorofluoroolefins in the Atmosphere

Hydrofluoroolefins\n(HFOs) and hydrochlorofluoroolefins (HCFOs)\nare the leading synthetic replacements for compounds successively\nbanned by the Montreal Protocol and amendments. HFOs and HCFOs readily\ndecompose in the atmosphere to form fluorinated carbonyls, including\nCF<sub>3</sub>CHO in yields of up to 100%, which are then photolyzed.\nA long-standing issue, critical for the transition to safe industrial\ngases, is whether atmospheric decomposition of CF<sub>3</sub>CHO yields\nany quantity of CHF<sub>3</sub> (HFC-23), which is one of the most\nenvironmentally hazardous greenhouse gases. This comprehensive experimental\ninvestigation employs purpose-built photoionization mass spectrometry,\nFourier-transform infrared, and microwave spectroscopy techniques\nand confirms production of CHF<sub>3</sub> following excitation at\na tropospherically relevant wavelength (λ = 308 nm) and under\natmospheric pressure conditions. Pressure-dependent CHF<sub>3</sub> quantum (Φ) and molar (<i>Y</i>) yields are reported\nfrom Φ = <i>Y</i> = 0.16 ± 0.03 under collision-free\nconditions to Φ = (2.3 ± 0.3) × 10<sup>–4</sup>, <i>Y</i> = (1.17 ± 0.27) × 10<sup>–3</sup> at 1 bar N<sub>2</sub>.