Zusammenfassung
Self-diffusion coefficients D were studied for fluid hydrogen and fluid deuterium at pressures up to 200 MPa and in the temperature range 171-372 K by the spin echo method. Spin-lattice relaxation times of both nuclei were measured in the same p,T range. The diffusion coefficients D are described by the rough hard sphere (RHS) model invoking the rotation translation coupling parameter A=1. ...
Zusammenfassung
Self-diffusion coefficients D were studied for fluid hydrogen and fluid deuterium at pressures up to 200 MPa and in the temperature range 171-372 K by the spin echo method. Spin-lattice relaxation times of both nuclei were measured in the same p,T range. The diffusion coefficients D are described by the rough hard sphere (RHS) model invoking the rotation translation coupling parameter A=1. Activation parameters are also derived. The dynamic isotope effect of D given by D-r=D(H-2)/D(D-2) is a function of p and T and varies from D(r)approximate to1.1 at the lowest pressures and highest temperatures to D(r)approximate to1.3 for the highest pressures and lowest temperatures reached. The spin-lattice relaxation is for both compounds dominated by the spin-rotation interaction. Only for T-1(H-2) at T=171 K can a minor contribution from dipole-dipole relaxation be derived from the data.
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