F-19 NUCLEAR-MAGNETIC-RESONANCE RELAXATION ANALYSIS OF THE INTERACTION OF FLUOROCARBON WITH OXYGEN

Fluorine-19 nuclear spin relaxation rates for fluorocarbon solutions involving oxygen have been measured over a wide frequency range (10 to 235 MHz) at 25-degrees-C. The F-19 relaxation of the solvents involving paramagnetic oxygen can be explained by dipolar electron spin-nuclear spin interaction modulated by both translational diffusion (tau(d) of 2.0X10(-11) and 2.5X10(-11) s for C6F6 and C6H4(CF3)2, respectively) and the lifetime of the short-lived complex (tau(h) of 7.6X10(-13) and 1.3X10(-12)s for C6F6 and C6H4(CF3)2, respectively), although the translational contribution is dominant. The translational motions account for 81 and 70% of the relaxation process and are characterized in the present analysis by closest distances of 3.6 and 3.8 A for C6F6 and C6H4(CF3)2, respectively.