Low‐field NMR

Abstract

Low‐field nuclear magnetic resonance (NMR) is an emerging area in both industry and academia with many exciting applications ranging from liquids to solids, from small to large molecules, the latter including biologics and animal/human tissue samples. I have had the privilege in my career to learn and work in all ranges of NMR, from high to low magnetic fields. Therefore, it has been an honor and a great opportunity to serve as the Guest Editor of this Special Issue on “Low Field NMR” for Magnetic Resonance in Chemistry. Early in the development of NMR, instruments considered today as “low field” were the starting point of the discipline. The first Nobel Prize in NMR was awarded to Bloch and Purcell in 1952 for the successful measurement of the magnetic moment of protons in water and parafilm using low‐field NMR instruments with a field of 7000 Gauss (0.7 Tesla or 30 MHz for H observation). This work was the beginning of the solid and liquid state NMR we know today. Bloembergen, Purcell, and Pound studied the factors that affect relaxation and pioneered the development of field cycling (FC), as well as magnetic resonance imaging (MRI). Their work provided the knowledge of the fundamental role of the relaxation times of materials. Over the years, low‐field NMR applications have expanded to numerous fields and industries. This special issue contains a variety of articles ranging from structure analysis to relaxometry, diffusometry, quantitation by time‐domain, (fast) field cycling, and data processing algorithms for relaxometry. All of these applications are represented in the cover picture of this issue by the colorful leaves of the bird of paradise flower blooming and pointing in many directions and still growing. In this special issue, we are presenting a variety of topics that have enhanced low‐field NMR. There are eleven articles (one review, two mini‐reviews, and eight research articles) covering a variety of topics that demonstrate the diverse scientific approaches utilized to solve challenging problems from chemistry to biology and mathematical development for better data processing in relaxometry. Portable low‐field NMR instruments are key for real‐time chemical process understanding, control, and optimization that is discussed in this issue on applications in the pharmaceutical industry (Weidener,