INFRARED DISPERSION MEASUREMENTS OF CARBON $TETRAFLUORIDE^{*}$

1R. L. Kelly, R. Rollefson, and B. Schurin, Jour. Chem. Phys. 19, 1595 (1951). $^{*}$This work was supported in part by grants in aid from the Wisconsin Alumni Research Foundation. $^{\dagger}$Now at Geophysics Research Directorate, Air Force Cambridge Research Center.Author Institution: Department of Physics, University of Wisconsin“The refractive index of carbon tetrafluoride has been measured in the infrared region of the spectrum and the data used to investigate the distribution of charge associated with the molecular bond. The apparatus and method used to measure the infrared dispersion is essentially the same as that reported in previous $works.^{1}$ Monochromatic radiation is obtained from a Wadsworth type monochromator utilizing either NaCl or KBr optics. The radiation is passed through a hollow prism containing the gas being studied and the change in deviation produced by a change in pressure is taken as a measure of the refractive index. The measurements have been made between 1 and 20 microns and the absolute intensities of the two infrared active bands ($\nu_{s}, \nu_{4}$) determined from their contribution to the index. The results are: ${A}_{3}=(1.60\pm 0.04)\times 10^{14}{ cm }^{-1}/{sec}$ ${A}_{4}=(1.86\pm 0.17)\times 10^{12}{ cm }^{-1}/{sec}.$ The results have been interpreted with the aid of a Urey-Bradley type potential to yield alternate solutions for the dipole moment ($\mu$) of the C-F bond in the molecule and the variation of the moment with internuclear distance (${d}\mu/{dr}$). These are: \frac{{d}\mu}{{dr}}=7.71 { d/a } \frac{{d}\mu}{{dr}}=3.71 { d/A } or \mu=1.13{d} \mu=3.97{d}