Progress Towards Measuring the Nuclear Spin Coherence of Molecules in Solid Parahydrogen

Prior experiments have demonstrated long nuclear spin coherence times for matrix-isolated molecules in solid parahydrogen. The nuclear spin coherence was limited by the presence of orthohydrogen impurities [Journal of Low Temperature Physics 45, 167 (1981)]. We have demonstrated the ability to grow solid hydrogen samples with orthohydrogen fractions that are orders-of-magnitude lower than this prior work [Review of Scientific Instruments 92, 073202 (2021)]. The objective of our current research is to use NMR techniques to measure the nuclear spin coherence times of molecules trapped in these high-purity parahydrogen matrices. If, as expected, long coherence times are achieved, this would be of interest for fundamental physics measurements. We are in the process of completing construction of an apparatus capable of performing such measurements for a variety of molecules; progress towards this goal will be presented.