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UBC Theses and Dissertations

Spin-lattice relaxation in gaseous methane Beckmann, Peter Adrian


The spin-lattice relaxation time T₁ has been measured in gaseous CH₄ as a function of density at room temperature. The density region investigated is from 0.006 to 7.0 amagats and T₁ passes through a minimum near 0.04 amagats. The spin-rotation interaction is the dominant relaxation mechanism in gaseous CH₄. Since the spin-rotation constants are accurately known for CH₄, the results provide a check on the existing theory of spin-lattice relaxation for spherical top molecules. An interesting feature was the failure of commonly used theoretical expressions for the density dependence of T₁ to fit the experimental data. A reasonable explanation is that the centrifugal distortion of the CH₄ molecule is indirectly contributing to the spin-lattice relaxation.

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