Reorientational and angular momentum correlation times in gaseous tetrafluoromethane at moderate densities

Abstract
NMR 19F spin-lattice relaxation times and Raman 435 cm−1 doubly degenerate [ν2(e)] vibrational-rotation band shapes have been measured in gaseous carbon tetrafluoride at 25 °C and densities of 9 to 120 amagat. NMR spin-lattice relaxation times have also been measured over the temperature range of −60 to 40 °C for the above densities. The Fourier transform analysis of the Raman band shapes has allowed us to calculate the reorientational correlation time τθ,2. Since spin rotation interactions provide the dominant relaxation mechanism for fluorine in CF4, then the angular momentum correlation time τJ is obtained directly from the 19F T1 relaxation times with the assumption that the anisotropy of the spin-rotation interaction tensor is small. A comparison of our experimental τθ,2 and τJ relationship agrees well with that predicted by the dilute gas limit of Gordon's J - and M -diffusion model as extended to classical spherical molecules by McClung.