High pressure nuclear magnetic resonance measurement of spinndash;lattice relaxation and selfhyphen;diffusion in carbon dioxide

摘要

Spinndash;lattice relaxation time and selfhyphen;diffusion coefficient in13CO2have been measured on the four isotherms 0, 25, 50, and 75thinsp;deg;C at pressures ranging from 10 to 500 bar. The governing relaxation mechanism in this range is shown to be spinndash;rotation relaxation. Low pressureT1data are adequately described by Gordonrsquo;s theory, while high pressureT1data agree semiquantitatively with the diffusion model proposed by Hubbard. The low density selfhyphen;diffusion coefficient behavior is in agreement with the kinetic theory of the dilute gas phase. Strong divergence from Enskog theory is observed in the dense gas and liquid phases. The hardhyphen;sphere theory predicts the selfhyphen;diffusion coefficient within plusmn;2percnt; at densities above 1.5 rgr;c. The simple hydrodynamic theory predicts the selfhyphen;diffusion coefficient within plusmn;5percnt; at densities above 1.5 rgr;c.