Parahydrogen Induced Polarization Studies Using a Continuous-Flow Homogeneous Hydrogenation Reactor

Nuclear magnetic resonance spectroscopy (NMR) is a valuable tool for obtaining structural and dynamical information of molecules. However, the method suffers from poor sensitivity compared to most other types of spectroscopy. In recent years, substantial efforts have been made to improve the sensitivity of the technique. Hyperpolarization methods such as parahydrogen induced polarization (PHIP), dynamic nuclear polarization (DNP), and spin exchange optical pumping can increase NMR signals by several orders of magnitude. NMR relies on the Zeeman effect to polarize spins in the presence of a magnetic field. The numbers of spins at each energy level, Nα and Nβ, follows the Boltzmann distribution, where E is the nuclear spin Zeeman energy. The amplitude of the NMR signal is proportional to Nα-Nβ. Hyperpolarization methods increase the population difference, Nα-Nβ, effectively lowering the spin temperature down to the mK regime. N N (1)