Measurement report: Radiative efficiencies of (CF₃)₂CFCN, CF₃OCFCF₂, and CF₃OCF₂CF₃

Abstract. Absorption cross sections of emerging greenhouse gases (GHGs) were measured to estimate the radiative efficiency using high-resolution Fourier transform infrared spectroscopy (HR-FTIR). For quantitative spectroscopy, Beer–Lambert parameters absorber pressure, temperature, and optical path length (OPL) accurately determined be traceable primary standards. The OPL multipass cell mounted on HR-FTIR spectrometer was spectroscopically calibrated. A ratio averaged N2O absorptions found in range 2217.4–2219.0 cm−1, with a spectral resolution 0.026 yielding OPLs between reference cell. This cell-to-cell comparison method is free from uncertainty referring line strength, which reduced calibration compared direct line-strength method. With OPL-calibrated (3.169 ± 0.079 m), absorption at low pressures 2 integrated 10 cm−1 intervals, multiplied by new narrow band model yield efficiencies. values CF4, SF6, NF3 evaluated 0.085 0.002, 0.573 0.016, 0.195 0.008 W m−2 ppb−1, respectively, are consistent previously reported values. GHGs, 0.201 ppb−1 for heptafluoroisobutyronitrile (CF3)2CFCN; commercially referred as Novec-4710), 0.328 0.013 perfluoro methyl vinyl ether (CF3OCFCF2; PMVE), 0.544 0.022 1,1,1,2,2-pentafluoro-2-(trifluoromethoxy)ethane (CF3OCF2CF3; PFMEE).