It is proposed that the nuclear magnetic resonance of sites which release dihydrogen can be obtained by measuring the branching fraction to the ortho and para forms. The motivation is to transform the sensitivity problem from that of detecting magnetization into the more tractable one of establishing the para and ortho content of free H2. It is shown with a density operator formalism that the para mole fraction reports directly on the zero-quantum coherence of the precursor and that other spin operators may be observed indirectly. Spectra are simulated for the case of a surface site from which H2 is released.
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