Zero- to Ultralow-field Control of Hyperpolarized Nuclear Spin Orders in Acetonitrile Solvent

Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) provides ac- cess to untruncated spin-spin interactions and—with its simplified instrumentation demands—emerges as a promising tool for chemical fingerprinting and fundamental physics. However, ZULF NMR J-spectra typically suffer from poor signal-to-noise ra- tios (SNRs) due to the low natural abundance of many heteronuclei. In this work we employ hyperpolarization via Signal Amplification by Reversible Exchange (SABRE) and various preparation, evolution, and signal detection schemes to demonstrate the control of many (10+) hyperpolarized nuclear spin orders in the XA3 spin system di- rectly inside a ZULF apparatus (here X corresponds to the 15N spin and A3 corresponds to the three protons). Acetonitrile solvent with natural isotopic abundance is used as a chemical model of the XA3 system. The results underscore the versatility and precision of ZULF NMR, highlighting its potential for applications in precision chemistry and fundamental physics.