Nuclear Spin Coherence of Molecules Trapped in Solid Parahydrogen

We use NMR techniques to measure the T2* and T2 coherence times of HD molecules trapped in parahydrogen matrices. We can control the level of orthohydrogen impurities in our matrix, and we find that T2* scales inversely with the orthohydrogen fraction. We are able to resolve the ~50 Hz splitting of the proton resonance due to nuclear spin-spin interactions in the HD molecule. We are exploring the limits on T2* in this system. If similarly long coherence times can be obtained for certain heavy polar molecules, this system would be of interest for experimental searches for T violation.