SPIN-LATTICE RELAXATION IN DILUTE GASES .3. 1H RELAXATION IN NH3 AND 19F RELAXATION IN BF3

Spin-lattice relaxation times have been measured for the protons in gaseous NHa and for the fluorine nuclei in gaseous BF3 as a function of temperature and pressure in the dilute gas region. The measured temperature dependences are as predicted for relaxation resulting from a spin-rotation interaction. Cross sections for the relaxation are calculated and from them it is deduced that the long-range forces between the molecular electric dipole moments in NH3 contribute significantly to the randomization of the molecular rotational magnetic fields at the proton sites.