Observation of the influence of centrifugal distortion of the methane molecule on nuclear spin relaxation in the gas.

Authors

Peter A. Beckmann, Bryn Mawr CollegeFollow
M. Bloom
E. E. Burnell

Document Type

Article

Version

Author's Final Manuscript

Publication Title

Canadian Journal of Physics

Volume

50

Publication Date

1972

Abstract

The spin–lattice relaxation time T₁ was measured in gaseous CH₄ as a function of density at room temperature between 0.006 and 7.0 amagats. T₁ was found to pass through a minimum near 0.04 amagats in agreement with previous, less precise measurements. The spin–rotation interaction is the dominant relaxation mechanism in gaseous CH₄. Since the spin–rotation constants are accurately known for CH₄, the relaxation experiments provide a check on the theory of spin–lattice relaxation for spherical top molecules. In the conventional theory, it is assumed that the correlation function of the spin–rotation interaction is a simple exponential function of time. These experiments show that this assumption is not true for CH₄ gas. The observed fine structure in the plot of relaxation rate versus density is attributed to the influence of centrifugal distortion of the CH₄molecule, which removes the degeneracy of rotational states having the same value of the quantum number J by an amount somewhat greater than the nuclear Larmor frequency of 30 MHz.

Citation

Beckmann, Peter A., M. Bloom, and , E. E. Burnell. 1972. "Observation of the influence of centrifugal distortion of the methane molecule on nuclear spin relaxation in the gas." Canadian Journal of Physics 50.3: 251-258.

DOI

https://doi.org/10.1139/p72-039