NMR Relaxation Behavior of Perfluorinated Gases

NMR Relaxation Behavior of Perfluorinated Gases 3.5.3.1 Introduction to Gas Phase Relaxation 

For liquids, the dominant relaxation mechanism is the nuclear-nuclear dipole interaction, in which simple motion of one nucleus with respect to the other is the most common source of relaxation [12, 27]. In the gas phase, however, the physical mechanism of relaxation is often quite different. For gases such as the ones listed above, the dominant mechanism is the spin-rotation interaction, in which molecular collisions alter the rotational state of the molecule, leading to rotation-induced magnetic fluctuations that cause relaxation [27]. The equation governing spin-rotation relaxation is given by 

It has been established by Dong and Bloom [29] and Courtney and Armstrong [30] that this equation can be translated into one based upon the kinetic theory of gases using 

However, these parameters are temperature and Larmor frequency dependent. Such a model can be conveniently parameterized in terms of collision frequency (/), so that the rate of decorrelation is given by 

2 NMR Relaxation of Liquids Versus Cases in Porous Media 

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