Concepts in NMR - up to 32A, 2008

Concepts in NMR - up to 32A, 2008

More on line broadening and uncertainty by Szántay, and a discussion on measurement of internuclear distances by Khitrin.

Concepts Magn Reson Part A 32A: 1-33, 2008.
NMR and the uncertainty principle: How to and how not to interpret homogeneous line broadening and pulse nonselectivity. II. The Fourier connection
Csaba Szántay Jr. *
Spectroscopic Research Division, Gedeon Richter Plc., H-1475 Budapest, 10, POB 27, Hungary
email: Csaba Szántay (cs.szantay@richter.hu)

Keywords uncertainty principle • Fourier analysis • Fourier transform

Abstract
By building on the nomenclature introduced and the fundamental ideas discussed in Part I, I now continue my preliminary review of the basic concepts we need for exploring the issues surrounding the uncertainty principles in the context of our Two NMR Problems (namely: both the essense of homogeneous NMR line broadening, as well as the fact that a short monochromatic RF pulse exhibits a polychromatic spectral bandwidth, and consequently gives a broad off-resonance NMR excitation band, are often rationalized in terms of a superficial and/or misguided use of the uncertainty principle). To that end, in Part II, I discuss Fourier theory in a way that is hoped to offer a number of delicate, important, and interesting insights that are usually not readily available from more conventional texts. © 2008 Wiley Periodicals, Inc.

Digital Object Identifier (DOI) 10.1002/cmr.a.20102

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Concepts Magn Reson Part A 32A: 56-67, 2008.
High-precision measurement of internuclear distances using solid-state NMR
Jae-Seung Lee *, Anatoly K. Khitrin
Department of Chemistry, Kent State University, Kent, OH 44242-0001
email: Jae-Seung Lee (jlee2@kent.edu)
Keywords heteronuclei • adiabatic cross-polarization • dipolar coupling • static solid • internuclear distance

Abstract
Today, nuclear magnetic resonance (NMR) is among the most efficient tools in structural studies. Measurement of interatomic distances is the most common way of determining high-resolution structures of molecules using NMR techniques. In this article, we describe NMR techniques for static powder samples, based on a two-dimensional single-echo scheme, enhanced with adiabatic cross-polarization. They can significantly increase the accuracy of measuring internuclear distances and turn NMR into a high-precision crystallographic technique, complementing the X-ray, and neutron-scattering methods. Experimental examples are presented for intramolecular CN and CC distances in -crystalline form of glycine. © 2008 Wiley Periodicals, Inc.
Received: 1 June 2007; Revised: 16 August 2007; Accepted: 20 August 2007
Digital Object Identifier (DOI) - 10.1002/cmr.a.20101 About DOI

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