Evaluation of the atmospheric lifetime and radiative forcing on climate for 1,2,2,2-Tetrafluoroethyl Trifluoromethyl Ether (CF₃OCHFCF₃)

The compound 1,2,2,2-Tetrafluoroethyl Trifluoromethyl Ether, CF₃OCHFCF₃ (HFE-227), is currently being considered as a potential replacement for certain halocarbons, particularly for perfluorocarbons (PFCs), as a dry etching gas in the semiconductor industry. For this reason, it is important to determine the potential environmental effects resulting from the use and emissions of this compound. In this paper, the atmospheric lifetime, radiative forcing, and Global Warming Potentials (GWPs), an important measure of the potential effects of a gas on climate, are evaluated for this compound using our zonally averaged chemical transport and radiative transfer models of the atmosphere. To our knowledge, this is the first time this compound has been evaluated with such atmospheric models. In order to calculate the lifetime and radiative forcing, the rate constants and infrared cross sections of this compound were measured in laboratories at Illinois and Purdue, and results are reported here. The model-evaluated atmospheric lifetime is 11.3 years, mainly due to reaction with OH radicals. The model-evaluated instantarieous-clear-sky radiative forcing is 0.38 W m^-2 ppbv^-1, about 45% lower than previously estimated [Imasu et al., 1995]. However, the model-estimated cloudy-sky adjusted forcing, needed to calculated GWPs, is about 25% lower than the model-estimated instantaneous-clear-sky forcing. The GWPs are calculated to be 3400, 1200, and 370 for 20, 100, and 500 year time horizons, respectively.