INTERMOLECULAR VERSUS INTRAMOLECULAR INTERACTIONS IN NUCLEAR-SPIN CONVERSION - EXPERIMENTS ON (CH3F)-C-13-O-2

Ortho-para conversion for gaseous (CH3F)-C-13 is measured in mixtures with O-2. As collision partner, O-2 is found to be 4 times less effici ent for conversion that CH3F itself. This demonstrates that intramolec ular rather than intermolecular magnetic interactions provide the main pathway leading to nuclear spin conversion for such molecules. (C) 19 95 American Institute of Physics.