Functionality of an NMR spectrometer

In an NMR spectrometer, the atomic nuclei interact with a statistical, homogeneous field that they are inserted into. The NMR spectrometer assists in examining the electronic environment of single atoms and their interaction with the adjacent atoms. However, NMR spectroscopy can be applied only to atoms with an odd nucleon number, because otherwise a magnetic field would not deflect them. The examination of hydrogen and carbon nuclei by ¹H and ¹³C NMR spectroscopy is the most common application. The gained spectra permit conclusions about the structure of molecules and their dynamic effects, such as the reaction mechanisms.

History of NMR spectroscopy

The molecular beam experiment by Otto Stern in 1933 is considered the first experimental proof of the proton spin. By this test it was possible to show that a proton beam is divided by a magnetic field into two halves. This fact can be described by the two different spin states. Rabi carried out the first magnetic resonance experiments with a modified Stern-Gerlach experiment, for which he received in 1944 the Nobel prize of physics. Also in 1944, the first successful magnetic resonance experiment in condensed matter was carried out by Zavoisky. Harry Pfeifer performed the first successful NMR experiments in Leipzig, 1951. From this time, NMR spectroscopy started to develop into one of the most important methods in chemical structure verification. The first commercial magnetic resonance spectrometer was built by the company Varian, in 1952.

Application of NMR spectrometers

Magnetic resonance spectroscopy is applied above all for molecules in dissolved state which do not interact with paramagnetic substances. NMR spectroscopy is also possible for solids and paramagnetic substances. Processing is here much more complicated, though. Main application areas of NMR spectroscopy are the non-destructive proof of contents in a sample, the determination of molecules or the examination of interactions between molecules. In addition, the spin-lattice relaxation times deliver information about the structure of a substance.

Literature

• http://de.wikipedia.org/w/index.php?title=Kernspinresonanzspektroskopie&oldid=85754585 (called: 30.03.11).

• http://buch.nmrguide.info/html.txt/german/index.shtml (called: 30.03.11).

• http://www.chemgapedia.de/vsengine/tra/vsc/de/ch/3/anc/kernresonanz_1.tra.html (called: 30.03.11).