Nuclear magnetic resonance (NMR), conventionally detected in multi-teslamagnetic fields, is a powerful analytical tool for the determination ofmolecular identity, structure, and function. With the advent of prepolarizationmethods and alternative detection schemes using atomic magnetometers orsuperconducting quantum interference devices (SQUIDs), NMR in very low-(~earth's field), and even zero-field, has recently attracted considerableattention. Despite the use of SQUIDs or atomic magnetometers, low-field NMRtypically suffers from low sensitivity compared to conventional high-field NMR.Here we demonstrate direct detection of zero-field NMR signals generated viaparahydrogen induced polarization (PHIP), enabling high-resolution NMR withoutthe use of any magnets. The sensitivity is sufficient to observe spectraexhibiting 13C-1H J-couplings in compounds with 13C in natural abundance in asingle transient. The resulting spectra display distinct features that havestraightforward interpretation and can be used for chemical fingerprinting.
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