Absorption cross-sections, radiative efficiency and global warming potential of HFE-347pcf2 (1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether)

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Highlights

  • Investigation of HFE-347pcf2 (1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether).

  • Acquisition of experimental absorption cross sections in the 550–3500 cm−1 range.

  • Extension of the spectrum in the low wavenumbers by theoretical simulations.

  • A radiative efficiency of 0.46 W m−2 ppb−1 and a 100-year global warming potential of 980 have been calculated.

Abstract

Composite absorption cross-sections of the hydrofluoroether HFE-347pcf2 (CAS number 406-78-0) have been determined from experimental and theoretical data. The experimental cross-sections have been used as a gauge to evaluate the accuracy of computational data obtained from different density functional theory methods. The B3LYP functional with a small 6-31G(d) basis set was found to provide the best results. A simulated spectrum was added to our experimental data to calculate the radiative efficiency and global warming potential of the molecule over the entire atmospheric spectral window. We found a radiative efficiency of 0.46 Wm−2ppb−1 and a 100-year global warming potential of 980.

Introduction

Hydrofluoroethers are cleaner alternatives to the ozone-depleting chlorofluocarbons and hydrofluorocarbons. HFE-347pcf2 (1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, CF3CH2OCF2CF2H, CAS number 406-78-0) is used in the composition of solvents in precision cleaning. Recent articles and patents have been submitted that make use of the molecule for plasma etching [1], solvent extraction [2], coating film-formation [3], and surface cold cleaning [4]. In 2016, this molecule was added to the list of compounds excluded from the regulatory definition of volatile organic compounds.

The main purpose of this study is to determine the radiative efficiency and global warming potential of HFE-347pcf2 from its experimental and theoretical absorption cross-section spectra. We also use this opportunity to determine which computational method gives the best simulation of the radiative properties of this HFE.

Section snippets

Setup and data processing

Experimental absorption spectra have been recorded at three different temperatures and at a resolution of 0.1 cm−1 using a Bomem DA8 spectrometer and a 10±0.1-cm-long gas cell. The spectrometer was operated with a globar source, a KBr beamsplitter, and a MCT detector. HFE-347pcf2 is a liquid at room temperature with a boiling point of 330 K and a vapour pressure of 213 Torr. The samples (Synquest Laboratories, stated purity of 99%) were therefore outgassed through several Freeze-pump-thaw

Methodology

The optimized geometry, vibrational frequencies and intensities of the conformers were calculated at different levels of theory using Gaussian 16. Hybrid density functional methods have been found to be more accurate for infrared intensities than MP2, nonlocal, or gradient-corrected methods [8]. More recent literature [9], [10] has shown that the density functional theory (DFT) B3LYP, B3PW91 and HSEH1PBE methods are the most accurate for vibrational frequencies. We have therefore compared our

Calculation of the radiative efficiency and global warming potential

The radiative efficiencies from our experimental and theoretical spectra were calculated using the modified Pinnock curve [14] from Shine and Myhre (2020) [15], which incorporates stratospheric temperature adjustment. The resulting values were adjusted by adding the fractional correction proposed by Hodnebrog et al. (2013) [16] for short-lived components to account for the nonuniform horizontal and vertical distribution in the atmosphere.

The global warming potential (GWP) of the molecule was

Conclusions

We have recorded the absorption spectra of HFE-347pcf2 in a range of pressures and extracted the composite cross-section spectra for three different temperatures. To gain access to the wavenumber spectral range below our experimental cutoff limit, simulations of the absorption cross section spectra were performed using multiple density functional theory methods. It was observed that the simplest basis set B3LYP 6-31G(d) give the best fit with our experimental data.

A radiative efficiency of

CRediT authorship contribution statement

Karine Le Bris: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing - original draft, Visualization, Supervision, Funding acquisition. Claire Yeo MacDougall: Investigation, Formal analysis. Paul J. Godin: Investigation, Writing - review & editing. Kimberly Strong: Resources, Writing - review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). Computational facilities were provided by ACEnet and Compute Canada.

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