Infrared absorption spectra of N(CxF2x+1)3, x = 2–5 perfluoroamines

Abstract

Infrared absorption spectra of the perfluoroamines (N(C2F5)3, N(C3F7)3, N(C4F9)3, and N(C5F11)3) were measured over the 500–4000 cm−1 spectral region at 294 K using Fourier transform infrared (FTIR) spectroscopy at 1 cm−1 resolution. Spectral measurements were performed using static measurements of dilute perfluoroamines mixtures and by infusion of the pure compound into a calibrated gas flow. The perfluoroamines absorb strongly in the “atmospheric window” with integrated band strengths (10−17 cm2 molecule−1 cm−1) between 570 and 1500 cm−1 of 59.9, 74.9, 88.9, and 98.7 for N(C2F5)3, N(C3F7)3, N(C4F9)3, and N(C5F11)3, respectively. Radiative efficiencies (RE) for the perfluoroamines were estimated to be 0.61, 0.75, 0.87, and 0.95 W m−2 ppb−1 for atmospherically well-mixed conditions and including a +10% stratospheric temperature correction for N(C2F5)3, N(C3F7)3, N(C4F9)3, and N(C5F11)3, respectively. Theoretical calculations of the perfluoroamines were performed at the B97-1/6-311++G(2df,2p) level of theory and optimized perfluoroamine geometries, vibrational band positions, and band strengths are reported. The theoretically calculated infrared spectra are in good agreement with the experimental spectra, while comparison of individual bands was not attempted due to the significant overlap of vibrational bands in the experimental spectra.