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Proton Enhanced Nuclear Induction Spectroscopy

Proton enhanced nuclear induction spectroscopy (P.E.N.I.S.) is a nuclear magnetic resonance technique invented by Michael Gibby and Alexander Pines while they were graduate students in the lab of Professor John S. Waugh at the Massachusetts Institute of Technology. It was patented in 1972.[1] It was one of the first of Pines' experiments transferring spin orientation from one atomic nucleus to another, which has been one of the running themes throughout his career as a leading pioneer in the applications of NMR to the study of non-liquid samples.

In this technique, the natural polarization of an abundant spin (1H, the "proton" which begins the name of the technique) is exploited to increase the polarization of a rare spin (such as 13C), by irradiating the sample with radio waves at the frequency which corresponds to the difference between the rotation frequencies of the two different spins.

Besides its obvious utility for boosting signals from dilute spins, transferring spin-polarization can also be used by surface-scientists, to selectively enhance the spin-polarization of molecules on a sample's surface over the spins in the bulk, by transferring spin-polarization from a gas to the surface.[2]


Proton-Enhanced Nuclear Induction Spectroscopy has caused some controversies because of its unsavory acronym.


1. ^ US patent 3792346
2. ^ Raftery, D.; MacNamara, E.; Fisher, G.; Rice, C. V.; Smith, J. (1997). "Optical Pumping and Magic Angle Spinning: Sensitivity and Resolution Enhancement for Surface NMR Obtained with Laser-Polarized Xenon". Journal of the American Chemical Society 119: 8746. doi:10.1021/ja972035d. edit

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