Increasing requirements of sensitivity and of spectral dispersion have driven the development of NMR magnets to higher and more homogeneous magnetic fields, which are obtained by immobile and expensive superconducting magnets. With the best field homogeneities available ( B/B ∼ 10 −9 over 1 cm 3 , where B is the magnetic field), ultrahigh-resolution carbon ( 13 C) NMR spectra at 4.2 T with an instrumental broadening below 50 mHz have been realized 2 . For 1 H high-field NMR spectroscopy (1-20 T), it is difficult to measure linewidths with an instrumental broadening below 100 mHz.We define our ideal NMR spectrometer by two requirements: first, it should measure NMR spectra with high resolution and all relevant NMR parameters, such as the longitudinal (T 1 ) and transverse (T 2 ) relaxation times, the chemical shift and the dipolar and J-coupling, in a single scan; and second, the spectrometer should be robust, low cost and mobile. Low cost and mobile means that heavy electro or superconducting magnets as well as superconducting quantum interference devices (SQUIDs) should be avoided. Single-scan and high-resolution NMR implies

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Conventional high resolution nuclear magnetic resonance (NMR) spectra are usually measured in homogeneous, high magnetic fields (>1 T), which are produced by expensive and immobile superconducting magnets. We show that chemically resolved xenon (Xe) NMR spectroscopy of liquid samples can be measured in the Earth's magnetic field (5 x 10(-5) T) with a continuous flow of hyperpolarized Xe gas. It was found that the measured normalized Xe frequency shifts are significantly modified by the Xe polarization density, which causes different dipolar magnetic fields in the liquid and in the gas phases.

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We present the theory and experimental results of phenomena associated to J-coupled nuclear magnetic resonance ͑NMR͒ spectroscopy at low magnetic fields ͑Ͻ10 −4 T͒. So far it was believed that in low field the chemical shift and with it the homonuclear J-coupling information is lost. This contribution shows that the network of all homo-and heteronuclear J-coupling constants can be measured in low magnetic fields, thus revealing the whole molecular structure even in the absence of any chemical shift information. The chemical group of the form YX N ͑Yϭrare spin 1 / 2, Xϭobserved spin 1 / 2, Nϭnumber of spins X͒ can be identified by the number of lines in the heteronuclear coupled X spectrum if the strong J-coupling condition is valid. If two molecular groups, such as YX N and AX M-N ͑Aϭgroup without nuclear spin, Mϭtotal number of coupled spins X͒, are bound together then all homo-and heteronuclear J-coupling constants appear in the X-NMR spectrum as pairs of multiplets. A vector model is presented which explains the relation between the molecular structure and the number of observed lines in a multiplet pair. The linewidths of the different NMR lines inside one multiplet are measured to be substantially different and depend on the total spin state of the molecule. If M is an odd number and M − 1 spins X of the molecule are coupled into ͑M −1͒ / 2 singlets, then intramolecular dipole-dipole relaxation as well as J-coupling mediated relaxation processes are suppressed and very narrow lines are observed.

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