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NMR
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<p>NMR studies magnetic nuclei by aligning them with an applied constant magnetic field and perturbing this alignment using an alternating magnetic field, those fields being orthogonal. The resulting response to the perturbing magnetic field is the phenomenon that is exploited in NMR spectroscopy and magnetic resonance imaging, which use very powerful applied magnetic fields in order to achieve high resolution spectra, details of which are described by the chemical shift and the Zeeman effect.</p>
<p>NMR phenomena are also utilised in low field NMR and Earth's field NMR spectrometers, and some kinds of magnetometer.</p>
<p> </p>
<h2><span class="mw-headline">History</span></h2>
<h4><span class="mw-headline">Spin behavior in a magnetic field</span></h4>
<p>Consider nuclei which have a spin of one-half, like <sup>1</sup>H, <sup>13</sup>C or <sup>19</sup>F. The nucleus has two possible spin states: <em>m</em> = ½ or <em>m</em> = -½ (also referred to as up and down or α and β, respectively). The energies of these states are degenerate—that is to say that they are the same. Hence the <em>populations</em> of the two states (i.e. number of atoms in the two states) will be approximately equal at thermal equilibrium.</p>
<div class="floatright"><span><img height="195" alt="Splitting of nuclei spin states in an external magnetic field" width="300" border="0" src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/EPR_splitting.jpg/300px-EPR_splitting.jpg" width="300" border="0" /></span></div>
<p>If a nucleus is placed in a magnetic field, however, the interaction between the nuclear magnetic moment and the external magnetic field mean the two states no longer have the same energy. The energy of a magnetic moment μ when in a magnetic field <em>B</em><sub>0</sub> (the zero subscript is used to distinguish this magnetic field from any other applied field) is given by the negative scalar product of the vectors:</p>
<dl><dd><img class="tex" alt="E = -{\mathbf B_0}\cdot{\mathbf \mu}= - \mu_z B_0" src="http://upload.wikimedia.org/math/c/a/a/caa447d9fefe8dcdeb1ba0804e52d0b8.png" /> </dd></dl>
<li>Solid-state NMR </li>
<li>Zeeman effect </li>
<li> </li> <li> </li> <li> </li>
</ul>
</div>
<li>Akitt, J.W.; Mann, B.E., ‘’NMR and Chemistry’’; Stanley Thornes: Cheltenham, UK, 2000. (p273) </li>
<li>Akitt, J.W.; Mann, B.E., ‘’NMR and Chemistry’’; Stanley Thornes: Cheltenham, UK, 2000. (p287) </li>
<li>Hornak, Joseph P. <a class="external text" title="http://www.cis.rit.edu/htbooks/nmr/" rel="nofollow" href="http://www.cis.rit.edu/htbooks/nmr/" rel="nofollow"><em>The Basics of NMR</em></a> </li> <li><a class="external text" title="http://www.spectroscopynow.com/Spy/basehtml/SpyH/1,,5-14-9-0-0-education_dets-0-1839,00.html" rel="nofollow" href="http://www.spectroscopynow.com/Spy/basehtml/SpyH/1,,5-14-9-0-0-education_dets-0-1839,00.html" rel="nofollow">J. Keeler, Understanding NMR Spectroscopy</a> </li>
<li>Wuthrich, Kurt <em>NMR of Proteins and Nucleic Acids</em> Wiley-Interscience, New York, NY USA 1986. </li>
<li>Tyszka, J. M. & Fraser, S. E. & Jacobs, R. E. (2005). <a class="external text" title="http://dx.doi.org/10.1016/j.copbio.2004.11.004" rel="nofollow" href="http://dx.doi.org/10.1016/j.copbio.2004.11.004" rel="nofollow">Magnetic resonance microscopy: recent advances and applications</a>. <em><a class="mw-redirect" title="Current Opinion in Biotechnology" href="http://en.wikipedia.org/wiki/Current_Opinion_in_Biotechnology">Current Opinion in Biotechnology</a>,</em> <strong>16</strong>(1):93-99. </li>
</ol>
<p><a id="External_links" name="External_links"></a></p>
<h2><span class="mw-headline">External links</span></h2>
<ul>
<li><a class="external text" title="http://www.vega.org.uk/video/programme/21" rel="nofollow" href="http://www.vega.org.uk/video/programme/21" rel="nofollow">Richard Ernst, NL - Developer of Multdimensional NMR techniques</a> Freeview video provided by the Vega Science Trust. </li> <li><a class="external text" title="http://www.vega.org.uk/video/programme/115" rel="nofollow" href="http://www.vega.org.uk/video/programme/115" rel="nofollow">'An Interview with Kurt Wuthrich'</a> Freeview video by the Vega Science Trust (Wüthrich was awarded a Nobel Prize in Chemistry in 2002 "for his development of nuclear magnetic resonance spectroscopy for determining the three-dimensional structure of biological macromolecules in solution"). </li> <li><em><a class="external text" title="http://abbreviations.oxid.ro/Academic-and-Science/Nuclear-Magnetic-Resonance/" rel="nofollow" href="http://abbreviations.oxid.ro/Academic-and-Science/Nuclear-Magnetic-Resonance/" rel="nofollow">Acronyms, Abbreviations and Initialisms - Nuclear Magnetic Resonance</a></em> </li> <li><a class="external text" title="http://vam.anest.ufl.edu/forensic/nmr.html" rel="nofollow" href="http://vam.anest.ufl.edu/forensic/nmr.html" rel="nofollow">A free interactive simulation of NMR principles</a> </li> <li><a class="external text" title="http://www.bionmr.com" rel="nofollow" href="http://www.bionmr.com/" rel="nofollow">Bionmr.com - discussion of NMR applications in biological systems</a> </li> <li><a class="external text" title="http://www.nmrwiki.org" rel="nofollow" href="http://www.nmrwiki.org/" rel="nofollow"><em>NMRW</em>iki.ORG</a> NMR resource you can edit </li> <li><a class="external text" title="http://www.ismar.org" hrefrel="nofollow" href="http://www.ismar.org/" rel="nofollow">The International Society of Magnetic Resonance</a> </li> <li><a class="external text" title="http://www.auremol.de" rel="nofollow" href="http://www.auremol.de/" rel="nofollow">AUREMOL (Universitaet Regensburg)</a> </li> <li>NMR processing software from <a class="external text" title="http://www.acdlabs.com/" rel="nofollow" href="http://www.acdlabs.com/" rel="nofollow">ACD/Labs</a> for <a class="external text" title="http://www.acdlabs.com/products/spec_lab/exp_spectra/nmr/" rel="nofollow" href="http://www.acdlabs.com/products/spec_lab/exp_spectra/nmr/" rel="nofollow">1D</a> and <a class="external text" title="http://www.acdlabs.com/products/spec_lab/exp_spectra/2d_nmr/" rel="nofollow" href="http://www.acdlabs.com/products/spec_lab/exp_spectra/2d_nmr/" rel="nofollow">2D</a> NMR spectra. DB interface available. </li> <li>NMR Prediction software <a class="external text" title="http://www.acdlabs.com/products/spec_lab/predict_nmr/" rel="nofollow" href="http://www.acdlabs.com/products/spec_lab/predict_nmr/" rel="nofollow">ACD/NMR Predictors</a> </li> <li>Automated elucidation of chemical structures <a class="external text" title="http://www.acdlabs.com/products/spec_lab/complex_tasks/str_elucidator/" hrefrel="nofollow" href="http://www.acdlabs.com/products/spec_lab/complex_tasks/str_elucidator/" rel="nofollow">ACD/Structure Elucidator</a> </li> <li>NMR simulation software <a class="external text" title="http://www.bpc.lu.se/QSim" rel="nofollow" href="http://www.bpc.lu.se/QSim" rel="nofollow">QSim</a> </li> <li>NMR processing software <a class="external text" title="http://spin.niddk.nih.gov/bax/software/NMRPipe" rel="nofollow" href="http://spin.niddk.nih.gov/bax/software/NMRPipe" rel="nofollow">NMRPipe</a> </li> <li><a class="external text" title="http://www.bmrb.wisc.edu/" rel="nofollow" href="http://www.bmrb.wisc.edu/" rel="nofollow">BMRB</a> BioMagResBank - A repository for experimental data from NMR spectroscopy of proteins, peptides, nucleic acids and small biomolecules. </li> <li><a class="external text" title="http://www.chemistry.ohio-state.edu/~grandinetti/RMN" rel="nofollow" href="http://www.chemistry.ohio-state.edu/~grandinetti/RMN" rel="nofollow">RMN</a> - An NMR data processing program for the Macintosh. </li> <li><a class="external text" title="http://baker-atlas.bakerhughesdirect.com/NMR-data-acquisition-systems/" rel="nofollow" href="http://baker-atlas.bakerhughesdirect.com/NMR-data-acquisition-systems/" rel="nofollow">Baker Hughes - NMR data acquisition systems</a> </li> <li><a class="external text" title="http://baker-atlas.bakerhughesdirect.com/NMR-data-logging/" hrefrel="nofollow" href="http://baker-atlas.bakerhughesdirect.com/NMR-data-logging/" rel="nofollow">Baker Hughes - The benefits of NMR data logging</a> </li> <li><a class="external text" title="http://www.process-nmr.com/time_domain_process_nmr_spectrom.htm" rel="nofollow" href="http://www.process-nmr.com/time_domain_process_nmr_spectrom.htm" rel="nofollow">Applications of Time-Domain NMR in Process Control</a> </li> <li><a class="external text" title="http://www.process-nmr.com/process.htm" rel="nofollow" href="http://www.process-nmr.com/process.htm" rel="nofollow">Applications of High Resolution FT-NMR in Real-Time Process Control</a> </li> <li><a class="external text" title="http://nmr.bham.ac.uk" rel="nofollow" href="http://nmr.bham.ac.uk/" rel="nofollow">HWB-NMR</a> Henry Wellcome Building for Biomolecular NMR, Birmingham, UK. </li> <li><a class="external text" title="http://www.nmr.ch/" rel="nofollow" href="http://www.nmr.ch/" rel="nofollow">CARA</a> - Computer Aided Resonance Assignment, freeware, developed at the group of Prof. Kurt Wüthrich </li> <li><a class="external text" title="http://www.ccpn.ac.uk/" rel="nofollow" href="http://www.ccpn.ac.uk/" rel="nofollow">CCPN</a> - The Collaborative Computing Project for NMR, based at the University of Cambridge, UK </li> <li><a class="external text" title="http://structbio.vanderbilt.edu" hrefrel="nofollow" href="http://structbio.vanderbilt.edu/" rel="nofollow">Vanderbilt Structural Biology</a> General site for structural biology at Vanderbilt University. NMR, x-ray crystallography, and computational biology all included. </li> <li><a class="external text" title="http://janocchio.sourceforge.net" rel="nofollow" href="http://janocchio.sourceforge.net/" rel="nofollow">Janocchio</a> Conformation-dependent coupling and NOE prediction for small molecules. </li> <li><a class="external text" title="http://www.teachspin.com/instruments/earths_field_NMR/index.shtml" rel="nofollow" href="http://www.teachspin.com/instruments/earths_field_NMR/index.shtml" rel="nofollow">Earth's field NMR (EFNMR)</a> </li> <li><a class="external text" title="http://www.chem.queensu.ca/FACILITIES/NMR/nmr/webcourse/precess.htm" rel="nofollow" href="http://www.chem.queensu.ca/FACILITIES/NMR/nmr/webcourse/precess.htm" rel="nofollow">Animation of NMR spin 1/2 precession</a> </li> <li><a class="external text" title="http://www.ebyte.it/stan/blog.html#08Feb29" rel="nofollow" href="http://www.ebyte.it/stan/blog.html#08Feb29" rel="nofollow">Article on helium scarcity and potential effects on NMR and MRI communities</a> </li>
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