Concentration of the Heavy Isotope of Carbon and Measurement of its Nuclear Spin

Citation

Townes, Charles Hard (1939) Concentration of the Heavy Isotope of Carbon and Measurement of its Nuclear Spin. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/106Z-3X75. https://resolver.caltech.edu/CaltechETD:etd-10222002-094724

Abstract

Heavy carbon was concentrated with a Hertz diffusion apparatus to a maximum of 50%, and enough carbon at 30 to 40% concentration was obtained to make possible spectroscopic and nuclear disintegration work. The concentration was in two processes. Ordinary methane was let continuously through the light reservoir of a Hertz apparatus for the collection of a large quantity of gas containing 6 or 7% heavy methane, then this gas reintroduced into the system for a final concentration. Measurements on the C¹³ - C¹³ band spectrum show that the C¹³ nucleus obeys Fermi-Dirac statistics and probably has a spin of 1/2. A 21 ft. grating and Lunmer-Gehrke plate combined were used to resolve the close λ type doublets of the O - O (λ 5165) band of the C¹³ - C¹³ Swan system. Resolution was not complete, but was enough to determine the nuclear statistics and allow a good estimate of the spin. Further proposed work with the concentrated heavy carbon is outlined and some conclusions drawn from isotopic effects in an unidentified band which has hitherto been assigned to the carbon molecule.

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