From Process/Industrial Instruments and Controls Handbook, 5th Edition


by John Edwards [*]

Nuclear Magnetic Resonance (NMR) spectroscopy is one of the most powerful experimental methods available for atomic and molecular level structure elucidation. It is a powerful technique in that it is noninvasive used to identify individual compounds, , aid in determining the structures of large molecules examine the kinetics of certain reactions, . From Nuclear Magnetic Resonance Spectroscopy in Environmental Chemistry, edited by Nanny et al. Oxford Univ. Press, 1997.

The property of nuclear spin, discovered by Rabi and coworkers in 1939, is the fundamental property for observing NMR. By analogy, a spinning nucleus is similar to an electric current flowing in a wire loop. In a wire loop, as charge flows around the loop, it generates an effective bar magnet whose polesare perpendicular to the current flow. Similarly, a nucleusspinning about its axis generates a small magnetic dipole, similar to a bar magnet. Since a dipole is present, a magnetic moment exists for that nucleus. Magnetic moments are defined as the torque felt by the nuclear charge divided by the strength of the applied magnetic field when the nuclear spins are placed in a magnetic field. This torque exists until the net magnetic moment is either aligned with the magnetic field (lower energy state) against the magnetic field (higher energy state) or perturbed from alignment with or against the magnetic field. As there are always slightly more spins aligned with the external magnetic field (lower...

Products & Services
NMR Spectrometers
NMR (Nuclear Magnetic Resonance) spectrometers are analytical devices that exploit the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained.
NMR Tubes

NMR tubes hold samples in NMR spectrometers. They are thin glass walled tubes, uniformly thick and balanced for smooth spinning.

NMR Probes
NMR probes incorporate radio frequency coils that are tuned for use in certain magnetic field strengths and detect specific nuclei. They can be switched out depending on the specific nuclei to be studied or the type of sample to be analyzed.
Spectrometer Repair Services
Spectrometer repair services provide a cost-effective solution for refurbishment and repair for all types of spectrometers and spectrometer system components.
Magnetic Receivers
Magnetic receivers use the electromagnetic principle to receive and analyze signals. The simplest of these devices is the telephone.

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This quick, one-time registration gives you access to members-only site benefits. Although less used than IR and NMR, in a process setting Raman does some things quite well. Unlike IR techniques,...

12.1 INTRODUCTION Nuclear magnetic resonance (NMR) spectroscopy is a powerful method for elucidating the structure of a molecule. The spectra obtained answer many questions such as the following...