Measurements of infrared absorption cross-sections for 1H-perfluorohexane and perfluoro-2-methyl-2-pentene from 300 to 340 K

Abstract

1H-perfluorohexane and perfluoro-2-methyl-2-pentene are polyfluoroalkyl and perfluoroalkyl substances, respectively. Such substances are of general interest due to their ubiquity in industry and adverse health effects. To our knowledge, perfluoro-2-methyl-2-pentene has not been measured before in the infrared, and a single measurement of 1H-perfluorohexane exists. This work provides infrared absorption cross-sections for each molecule between 515 and 4000 cm⁻¹ at 0.1 cm⁻¹ resolution from 300 to 340 K to quantify their potential climate impact. Our results can also aid in detecting both molecules during the disposal of heavier per- and polyfluoroalkyl substances. We supplement experimental measurements with density functional theory cross-sections using the DSD-BLYP-D3BJ functional and the def2-TZVPPD basis set. We calculate integrated cross-sections, radiative efficiencies, and global warming potentials from experimental and theoretical cross-sections. Based on experimental data, the 100-year global warming potentials are 3120±410 and 37±9 for 1H-perfluorohexane and perfluoro-2-methyl-pentene, respectively. Our experimental and density functional theory climate metrics are substantially smaller than the theoretical values provided in The Scientific Assessment of Ozone Depletion: 2022.