This research was funded by the International Research Training Group (IRTG) &#8220;Diffusion in porous Materials&#8221;. We acknowledge the technical support from Gert Klotzsche and stimulating discussions with Steven Reichhardt, Thomas Meissner, Damian Rybicki, Tobias Herzig, Natalya Georgieva, Jonas Kohlrautz, and Michael Jurkutat.

1. Mounting and Aligning of the 6H-SiC Large Cone Boehler-type Anvils
<ol>
	<li>Fix the piston and x-y plate in the mounting tools and insert the Boehler-type anvils in the seating area.</li>
	<li>Make sure each anvil sits firmly in the backing plates.</li>
	<li>Using epoxy resin, (e.g., Stycast 1266), glue both anvils to their seats. Cure for 12 h at RT, or 65 &#186;C in a furnace for 2 hr.</li>
	<li>For a sufficient anvil alignment, use the M1 set-screws to align the backing plates and monitor the parallelism of both anvils. If the anvils were found to be non-parallel, remove the epoxy resin and restart at point 1.2.</li>
</ol>
2. Gasket Preparation
<ol>
	<li>Drill 1 mm holes into a chip of annealed Cu-Be (Cu 98 w%, Be 2 wt%, thickness of 0.5 mm) for the brass guide pins.</li>
	<li>Insert three 5 mm long pieces of 1 mm diameter non-insulated copper wire into the holes, which are distributed along the anvil, to serve as guide pins for the Cu-Be gasket.</li>
	<li>Check for proper grounding between the guide pins and the cell body. Typically, a DC resistance of about 0.1 &#937; is desired. Improve with an application of a small amount of conductive silver.</li>
	<li>Place the Cu-Be chip on top of the moissanite anvil and close the cell.</li>
	<li>Using a hydraulic press, pressurize the gasket to about 1/8th of the culet diameter for maximized working stability. Monitor the actual thickness of the indentation using a micrometer caliper.</li>
	<li>Drill a hole of the appropriate diameter (&#189; of the culet diameter) in the center of the indentation.</li>
	<li>Carve two channels into the pre-indented gasket. The channels should be deep enough to accommodate the 18 &#181;m copper wire of the micro-coil.</li>
	<li>Harden the prepared gasket at 617 K for 2 to 3 hr in a furnace.</li>
</ol>
3. Preparing and Loading of the Micro-coil
<ol>
	<li>Use a piece of 1 mm copper wire and thread it through the feed-through of the piston. Fix the copper wire with epoxy resin and cure it according to step 1.3.</li>
	<li>Choose an awl (see list of materials) which has the desired diameter for the micro-coil and fix it between a pair of rotatable chuck-jaws.</li>
	<li>Glue (with e.g., varnish from SCB, see list of materials) one end of the 18 &#181;m copper wire onto the chuck jaws, while holding the other end and rotate the chuck jaw so that the wire is coiled onto the awl.</li>
	<li>When the micro-coil is of the desired geometry, fix the other end of the wire onto the glue as well.</li>
	<li>Use diluted varnish to fix the coil by applying a small amount on top of the windings.</li>
	<li>Remove the coil carefully from the awl using Teflon tape.</li>
	<li>Place some epoxy resin (see point 1.3), without any additives, in the channels of the gasket.</li>
	<li>Place the micro-coil inside the sample chamber and fix the leads into the channels.</li>
	<li>Cure the epoxy resin according to step 1.3.</li>
	<li>Solder one lead of the micro-coil to the hot wire and the other to a guide pin.</li>
	<li>Add some silver conductive paste on top of each junction. Curing typically takes some minutes.</li>
	<li>Seal both junctions with a small amount of epoxy resin.</li>
	<li>Cure the epoxy according to step 1.3.</li>
	<li>Now, check the DC resistance of the coil after every step.</li>
	<li>Place the sample in the micro-coil. Be aware that any unnecessary physical contact may destroy the coil.</li>
	<li>Add finely ground ruby powder to the sample for pressure calibration.</li>
	<li>Finally, flood the sample chamber with an appropriate pressure medium. Use paraffin oil to ensure nearly-hydrostatic conditions up to 9 GPa.</li>
	<li>Close the cell carefully.</li>
</ol>
4. Applying and Monitoring Pressure
<ol>
	<li>At first, slightly tighten the M3 Allen countersunk screws.</li>
	<li>For pressurization fix the cell in a vise. Now, tighten two opposing screws pairwise.</li>
	<li>Place the pressurized cell in an appropriate cell holder.</li>
	<li>Adjust the position of the cell so that the laser beam reaches the sample chamber.</li>
	<li>Use the fine-adjustment table to focus the ruby powder in the laser beam.</li>
	<li>Monitor the ruby photoluminescence spectrum using the corresponding spectrometer software.</li>
	<li>Extract the actual pressure in the sample cavity from the observed spectral shift of the ruby R1 and R2 lines.</li>
	<li>Equilibrate the pressurized cell for at least 12 hr before NMR measurements are started.</li>
</ol>
5. Performing NMR Experiments
<ol>
	<li>Mount the pressure cell onto a typical NMR probe. Manufacture appropriate cell holders in a mechanical workshop.</li>
	<li>Solder the hot wire to the probe. Check for proper electrical contact between the cell and the probe.</li>
	<li>Now, perform standard NMR experiments. Draw attention to the fact that the micro-coil is very sensitive to the applied radio-frequency power.</li>
</ol>

<ol>
	<li>Hemley, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Percy+Bridgman&#180;s+Second+Century.">Percy Bridgman&#180;s Second Century.</a> High Pressure Research. 30 (4), 581-619 (2010).</li><li>Grochala, W., Hoffmann, R., Feng, J., Ashcroft, N. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Chemical+imagination+at+work+in+very+tight+places.">The Chemical imagination at work in very tight places.</a> Angewandte Chemie (International Edition in English). 46 (20), 3620-3642 (2007).</li><li>Ma, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transparent+dense+sodium.">Transparent dense sodium.</a> Nature. 458 (7235), 182-185 (2009).</li><li>Eremets, M. I., Troyan, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conductive+dense+hydrogen.">Conductive dense hydrogen.</a> Nat Mater. 10 (12), 927-931 (2011).</li><li>Jayaraman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diamond+anvil+cell+and+high-pressure+physical+investigations.">Diamond anvil cell and high-pressure physical investigations.</a> Rev Mod Phys. 55 (1), 65-108 (1983).</li><li>Bertani, R., Mali, M., Roos, J., Brinkmann, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+diamond+anvil+cell+for+high-pressure+NMR+investigations.">A diamond anvil cell for high-pressure NMR investigations.</a> Rev Sci Instrum. 63 (6), 3303 (1992).</li><li>Lee, S. -. H., Luszczynski, K., Norberg, R. E., Conradi, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NMR+in+a+diamond+anvil+cell.">NMR in a diamond anvil cell.</a> Rev Sci Instrum. 58 (3), 415 (1987).</li><li>Lee, S. -. H., Conradi, M. S., Norberg, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+NMR+resonator+for+diamond+anvil+cells.">Improved NMR resonator for diamond anvil cells.</a> Rev Sci Instrum. 63 (7), 3674 (1992).</li><li>Pravica, M. G., Silvera, I. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+magnetic+resonance+in+a+diamond+anvil+cell+at+very+high+pressures.">Nuclear magnetic resonance in a diamond anvil cell at very high pressures.</a> Rev Sci Instrum. 69 (2), 479 (1998).</li><li>Lee, S. -. H., Conradi, M., Norberg, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+motion+in+solid+H2+at+high+pressures.">Molecular motion in solid H2 at high pressures.</a> Phys Rev B. 40 (18), 12492-12498 (1989).</li><li>Vaughan, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Apparatus+for+Magnetic+Measurements+at+High+Pressure.">An Apparatus for Magnetic Measurements at High Pressure.</a> Rev Sci Instrum. 42 (5), 626 (1971).</li><li>Yarger, J. L., Nieman, R. A., Wolf, G. H., Marzke, R. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Pressure+1H+and+13C+Nuclear+Magnetic+Resonance+in+a+Diamond+Anvil+Cell.">High-Pressure 1H and 13C Nuclear Magnetic Resonance in a Diamond Anvil Cell.</a> Journal of Magnetic Resonance Series A. 114 (2), 255-257 (1995).</li><li>Okuchi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+type+of+nonmagnetic+diamond+anvil+cell+for+nuclear+magnetic+resonance+spectroscopy.">A new type of nonmagnetic diamond anvil cell for nuclear magnetic resonance spectroscopy.</a> Physics of the Earth and Planetary Interiors. , 143-144 (2004).</li><li>Kluthe, S., Markendorf, R., Mali, M., Roos, J., Brinkmann, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure-dependent+Knight+shift+in+Na+and+Cs+metal.">Pressure-dependent Knight shift in Na and Cs metal.</a> Phys Rev B. 53 (17), 11369-11375 (1996).</li><li>Graf, D. E., Stillwell, R. L., Purcell, K. M., Tozer, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonmetallic+gasket+and+miniature+plastic+turnbuckle+diamond+anvil+cell+for+pulsed+magnetic+field+studies+at+cryogenic+temperatures.">Nonmetallic gasket and miniature plastic turnbuckle diamond anvil cell for pulsed magnetic field studies at cryogenic temperatures.</a> High Pressure Research. 31 (4), 533-543 (2011).</li><li>Pravica, M., Silvera, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NMR+Study+of+Ortho-Para+Conversion+at+High+Pressure+in+Hydrogen.">NMR Study of Ortho-Para Conversion at High Pressure in Hydrogen.</a> Physical Review Letters. 81 (19), 4180-4183 (1998).</li><li>Haase, J., Goh, S. K., Meissner, T., Alireza, P. L., Rybicki, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+sensitivity+nuclear+magnetic+resonance+probe+for+anvil+cell+pressure+experiments.">High sensitivity nuclear magnetic resonance probe for anvil cell pressure experiments.</a> Rev Sci Instrum. 80 (7), 73905 (2009).</li><li>Meissner, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Approach+to+High-Pressure+Nuclear+Magnetic+Resonance+with+Anvil+Cells.">New Approach to High-Pressure Nuclear Magnetic Resonance with Anvil Cells.</a> J Low Temp Phys. 159 (1-2), 284-287 (2010).</li><li>Meier, T., Herzig, T., Haase, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moissanite+Anvil+Cell+Design+for+Giga-Pascal+Nuclear+Magnetic+Resonance.">Moissanite Anvil Cell Design for Giga-Pascal Nuclear Magnetic Resonance.</a> Rev Sci Instrum. 85 (4), 43903 (2014).</li><li>Boyer, R. F., Collings, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Materials Properties Handbook: Titanium Alloys. , (1994).</li><li>Xu, J. -. a., Yen, J., Wang, Y., Huang, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrahigh+pressures+in+gem+anvil+cells.">Ultrahigh pressures in gem anvil cells.</a> High Pressure Research. 15 (2), 127-134 (1996).</li><li>Xu, J. -. a., Mao, H. -. k., Hemley, R. J., Hines, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+moissanite+anvil+cell+a+new+tool+for+high-pressure+research.">The moissanite anvil cell a new tool for high-pressure research.</a> J Phys Condens Matter. 14 (44), 11543-11548 (2002).</li><li>Xu, J. -. a., Mao, H. -. k., Hemley, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+gem+anvil+cell+high-pressure+behaviour+of+diamond+and+related+materials.">The gem anvil cell high-pressure behaviour of diamond and related materials.</a> J Phys Condens Matter. 14 (44), 11549-11552 (2002).</li><li>Meissner, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+magnetic+resonance+at+up+to+10.1+GPa+pressure+detects+an+electronic+topological+transition+in+aluminum+metal.">Nuclear magnetic resonance at up to 10.1 GPa pressure detects an electronic topological transition in aluminum metal.</a> J Phys Condens Matter. 26 (1), 15501 (2014).</li><li>Meissner, T., Goh, S. K., Haase, J., Williams, G. r. a. n. t. . V. M., Littlewood, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-pressure+spin+shifts+in+the+pseudogap+regime+of+superconducting+YBa2Cu4O8+as+revealed+by+17O+NMR.">High-pressure spin shifts in the pseudogap regime of superconducting YBa2Cu4O8 as revealed by 17O NMR.</a> Phys Rev B. 83 (22), (2011).</li><li>Goh, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+pressure+de+Haas&#8211;van+Alphen+studies+of+Sr2RuO4+using+an+anvil+cell.">High pressure de Haas&#8211;van Alphen studies of Sr2RuO4 using an anvil cell.</a> Current Applied Physics. 8 (3-4), 304-307 (2008).</li><li>Tateiwa, N., Haga, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluations+of+pressure-transmitting+media+for+cryogenic+experiments+with+diamond+anvil+cell.">Evaluations of pressure-transmitting media for cryogenic experiments with diamond anvil cell.</a> Rev Sci Instrum. 80 (12), 123901 (2009).</li><li>Hahn, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin+Echoes.">Spin Echoes.</a> Phys Rev. 80 (4), 580-594 (1950).</li><li>Boehler, R., Ross, M., Boercker, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Melting+of+LiF+and+NaCl+to+1+Mbar+Systematics+of+Ionic+Solids+at+Extreme+Conditions.">Melting of LiF and NaCl to 1 Mbar Systematics of Ionic Solids at Extreme Conditions.</a> Physical Review Letters. 78 (24), 4589-4592 (1997).</li><li>Funamori, N., Sato, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+cubic+boron+nitride+gasket+for+diamond-anvil+experiments.">A cubic boron nitride gasket for diamond-anvil experiments.</a> Rev Sci Instr. 79 (5), 053903 (2008).</li><li>Forman, R. A., Piermarini, G. J., Barnett, J. D., Block, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure+measurement+made+by+the+utilization+of+ruby+sharp-line+luminscence.">Pressure measurement made by the utilization of ruby sharp-line luminscence.</a> Science. 176 (4032), 284-285 (1972).</li></ol>

The authors have nothing to disclose.

A new and promising method to perform NMR at Giga-Pascal pressures was described. This method opens up the door to a broad variety of NMR experiments due to its excellent sensitivity and resolution. Nevertheless, several steps described in the protocol section are crucial to the outcome of the experiment. Especially, the preparation of the micro-coil and its fixation in the Cu-Be gasket is very difficult and requires some experience. In the following, some important tips are given, which should help a first successful ap...

Since Percy Bridgman&#39;s hallmark experiments of condensed matter under high hydrostatic pressures at the beginning of the last century, the field of high pressure physics has evolved rapidly1. A large number of intriguing phenomena are known to occur under pressures of several GPa2. In addition, the response of condensed matter systems to high pressure has taught us a lot about their electronic ground and excited states3,4.
Unfortunately, techniques for the investigation of the electronic properties of condensed matter at Giga-Pascal pressures are rare, with x-ray or DC resistance measurements leading the way5. In particular, the detection of electronic or nuclear magnetic moments with electron spin (ESR) or nuclear magnetic resonance (NMR) experiments, is bound to be almost impossible to implement in a typical high-pressure anvil cells where one needs to retrieve the signal from a tiny volume enshrined by anvils and a sealing gasket.
Several groups have tried to solve this problem by using complex arrangements, e.g., two split-pair radio-frequency (RF) coils wound along the flanks of the anvils6; a single or double loop hair-pin resonator7,8; or even a split rhenium gasket as a RF pick-up coil9, see Figure 1. Unfortunately, those approaches still suffered from a low signal-to-noise ratio (SNR), limiting the experimental applications to large-&#947; nuclei such as 1H10. The interested reader may be referred to other high-pressure resonant tank circuit experiments11&#8211;15. Pravica and Silvera16 report the highest pressure achieved in an anvil cell for NMR with 12.8 GPa, who studied the ortho-para conversion of hydrogen.
With great interest in applying NMR to study the properties of quantum solids, our group was interested in having NMR available at high pressures, as well. Finally, in 2009 it could be demonstrated that high-sensitivity anvil cell NMR is indeed possible if a resonating radio-frequency (RF) micro-coil is placed directly in the high-pressure cavity enclosing the sample17. In such an approach, the NMR sensitivity is improved by several orders of magnitude (mostly due to the dramatic increase in filling factor of the RF coil), which made even more challenging NMR experiments possible, e.g.,17O NMR on powder samples of a high-temperature superconductor at up to 7 GPa18. Superconductivity in these materials can be greatly amplified by the application of pressure, and it is now possible to follow this process with a local electronic probe that promises fundamental insight into the governing processes. Another example for the power of NMR under high pressure emerged from what were believed to be routine referencing experiments: in order to test the introduced new anvil cell NMR, one of the best known materials was measured &#8211; simple aluminum metal. As the pressure was increased, an unexpected deviation of the NMR shift from what one would expect for a free-electron system was found. Repeated experiments, also under increased pressures, showed that the new results were indeed reliable. Finally, with band structure calculations it was then found that the results are the manifestation of a topological transition of the Fermi surface of aluminum, which could not be detected by calculations years ago, when the computing power was low. Extrapolation of the findings to ambient conditions showed that the properties of this metal that is used almost everywhere are influenced by this special electronic condition.
In order to pursue a number of different applications specially designed anvil cells (previous cells had been imported from the Cavendish Laboratory and retrofitted for NMR) have been developed. Currently, the used home-built chassis are capable of reaching pressures up to 25 GPa using a pair of 800 &#181;m culet 6H-SiC anvils. NMR experiments were successfully conducted up to 10.1 GPa, so far. The NMR performance of this new cells was shown to be excellent19. The main component is Titanium-Aluminum(6)-Vanadium(4) with an extra low interstitial level (grade 23), providing a yield strength of about 800 MPa20. Due to its non-magnetic properties (the magnetic susceptibility &#967; is about 5 ppm) it is an adequate material for the anvil cell chassis. The overall dimensions of the introduced cells (see Figure 2 for an overview of all home-built anvil cell designs) are small enough to fit into regular standard bore NMR magnets. The smallest design, the LAC-TM1, which is only 20 mm in height and 17 mm in diameter, fits also typical small, cold-bore magnets (30 mm bore diameter). The LAC-TM2, which is the latest chassis the authors designed, uses four M4 Allen countersink bolts (made out of the same alloy as the cell chassis) as pressure driving mechanism, allowing for a smooth control of the internal pressure (blue prints attached in supplementary section).
Typically, diamond anvils are used in order to generate highest pressures of above 100 GPa. Xu and Mao21&#8211;23 have demonstrated that moissanite anvils provide a cost effective alternative in high-pressure research, up to pressures of about 60 GPa. Therefore, moissanite anvils were used for the introduced GPa NMR approach. The best results were achieved with customized large-cone 6H-SiC anvils from the anvil department of Charles &#38; Colvard. With those cells, for pressures up to 10.1 GPa, the use of 800 &#181;m culet anvils was found to result in very good NMR sensitivity. For comparison, Lee et al. report a SNR of 1 for 1H NMR of tap water, while the SNR of the introduced micro-coil approach showed a value of 25 for 1/7 of their volume, even at a somewhat lower magnetic field.
With this new approach to high-sensitivity anvil cell NMR one can pursue many applications that promise exciting new insight into the physics and chemistry of modern materials. However, as always, sensitivity and resolution ultimately limit the application of NMR, in particular, if one is interested in much higher pressures that demand smaller culet sizes. Then, one has not only to optimize the cell design with even smaller RF coils, but also think about methods for increasing nuclear polarization.

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high-sensitivity nuclear magnetic resonance at giga-pascal pressures: a new tool for probing electronic and chemical properties of condensed matter under extreme conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Figure 3 shows how the completely assembled pressure cell, the wiring, and the mounting onto a typical NMR probe look like. In the following, several experiments will be reviewed which should enable the reader to gather a broad overview about the benefits and limits of the introduced technique.
<img alt="Figure 1" src="/files/ftp_upload/52243/52243fig1highres.jpg" /> 
Figure 1.&#160;Various Approaches for high pressure NMR: (A...

Watch this Scientific Journal Video about High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extr

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

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Principles of Nuclear Magnetic Resonance

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11.5K Views.  University of Leipzig. Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Video: High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Hyperpolarized Xenon for NMR and MRI Applications

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2.
Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method.
The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode.

The production of hyperpolarized xenon by means of spin exchange optical pumping (SEOP) is described. This method yields a ~10000-fold enhancement of the nuclear spin polarization of Xe-129 and has applications in nuclear magnetic resonance spectroscopy and imaging. Examples of gas phase and solution state experiments are given.

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 ...

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic glasses (MGs). Despite their amorphous nature, the identification of hyperfine interactions unveils faint structural modifications. For this purpose, we have employed two techniques that utilize nuclear resonance among nuclear levels of a stable 57Fe isotope, namely M&#246;ssbauer spectrometry and nuclear forward scattering (NFS) of synchrotron radiation. The effects of heat treatment upon (Fe2.85Co1)77Mo8Cu1B14 MG are discussed using the results of ex situ and in situ experiments, respectively. As both methods are sensitive to hyperfine interactions, information on structural arrangement as well as on magnetic microstructure is readily available. M&#246;ssbauer spectrometry performed ex situ describes how the structural arrangement and magnetic microstructure appears at room temperature after the annealing under certain conditions (temperature, time), and thus this technique inspects steady states. On the other hand, NFS data are recorded in situ during dynamically changing temperature and NFS examines transient states. The use of both techniques provides complementary information. In general, they can be applied to any suitable system in which it is important to know its steady state but also transient states.

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Here, we present a protocol to describe ex situ and in situ investigations of structural transformations in metallic glasses. We employed nuclear-based analytical methods which inspect hyperfine interactions. We demonstrate the applicability of M&#246;ssbauer spectrometry and nuclear forward scattering of synchrotron radiation during temperature-driven experiments.

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic ...

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan electron-paramagnetic-resonance (RS-EPR), which can provide quantitative information under in vivo conditions on oxygen concentration, pH, redox status and concentration of signaling molecules (i.e., OH&#8226;, NO&#8226;). The RS-EPR technique has a higher sensitivity, improved spatial resolution (1 mm), and shorter acquisition time in comparison to the standard continuous wave (CW) technique. A variety of phantom configurations have been tested, with spatial resolution varying from 1 to 6 mm, and spectral width of the reporter molecules ranging from 16 &#181;T (160 mG) to 5 mT (50 G). A cross-loop bimodal resonator decouples excitation and detection, reducing the noise, while the rapid scan effect allows more power to be input to the spin system before saturation, increasing the EPR signal. This leads to a substantially higher signal-to-noise ratio than in conventional CW EPR experiments.

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

A new electron paramagnetic resonance (EPR) method, rapid scan EPR (RS-EPR), is demonstrated for 2D spectral spatial imaging which is superior to the traditional continuous wave (CW) technique and opens new venues for in vivo imaging. Results are demonstrated at 250 MHz, but the technique is applicable at any frequency.

We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan ...

Bioengineering

High-Pressure NMR Experiments for Detecting Protein Low-Lying Conformational States

High-pressure is a well-known perturbation method that can be used to destabilize globular proteins and dissociate protein complexes in a reversible manner. Hydrostatic pressure drives thermodynamical equilibria toward the state(s) with the lower molar volume. Increasing pressure offers, therefore, the opportunities to finely tune the stability of globular proteins and the oligomerization equilibria of protein complexes. High-pressure NMR experiments allow a detailed characterization of the factors governing the stability of globular proteins, their folding mechanisms, and oligomerization mechanisms by combining the fine stability tuning ability of pressure perturbation and the site resolution offered by solution NMR spectroscopy. Here we present a protocol to probe the local folding stability of a protein via a set of 2D 1H-15N experiments recorded from 1 bar to 2.5 kbar. The steps required for the acquisition and analysis of such experiments are illustrated with data acquired on the RRM2 domain of hnRNPA1.

We provide a detailed description of the steps required to assemble a high-pressure cell, set up and record high-pressure NMR experiments, and finally analyze both peak intensity and chemical shift changes under pressure. These experiments can provide valuable insights into the folding pathways and structural stability of proteins.

High-pressure is a well-known perturbation method that can be used to destabilize globular proteins and dissociate protein complexes in a reversible ...

Biochemistry

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by overlapping two parts of an electron wave, one of which has passed through a region of interest on a specimen and the other is a reference wave. The resulting off-axis electron hologram can be analyzed digitally to recover the phase difference between the two parts of the electron wave, which can then be interpreted to provide quantitative information about local variations in electrostatic potential and magnetic induction within and around the specimen. Off-axis electron holograms can be recorded while a specimen is subjected to external stimuli such as elevated or reduced temperature, voltage, or light. The protocol that is presented here describes the practical steps that are required to record, analyze, and interpret off-axis electron holograms, with a primary focus on the measurement of magnetic fields within and around nanoscale materials and devices. Presented here are the steps involved in the recording, analysis, and processing of off-axis electron holograms, as well as the reconstruction and interpretation of phase images and visualization of the results. Also discussed are the need for optimization of the specimen geometry, the electron optical configuration of the microscope, and the electron hologram acquisition parameters, as well as the need for the use of information from multiple holograms to extract the desired magnetic contributions from the recorded signal. The steps are illustrated through a study of specimens of B20-type FeGe, which contain magnetic skyrmions and were prepared with focused ion beams (FIBs). Prospects for the future development of the technique are discussed.

Guidelines are presented for recording and interpreting off-axis electron holograms to provide quantitative images of magnetic fields in nanoscale materials and devices in the transmission electron microscope.

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by ...

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy represents an important technique to understand the structure and bonding environments of molecules. There exists a drive to characterize materials under conditions relevant to the chemical process of interest. To address this, in situ high-temperature, high-pressure MAS NMR methods have been developed to enable the observation of chemical interactions over a range of pressures (vacuum to several hundred bar) and temperatures (well below 0 &#176;C to 250 &#176;C). Further, the chemical identity of the samples can be comprised of solids, liquids, and gases or mixtures of the three. The method incorporates all-zirconia NMR rotors (sample holder for MAS NMR) which can be sealed using a threaded cap to compress an O-ring. This rotor exhibits great chemical resistance, temperature compatibility, low NMR background, and can withstand high pressures. These combined factors enable it to be utilized in a wide range of system combinations, which in turn permit its use in diverse fields as carbon sequestration, catalysis, material science, geochemistry, and biology. The flexibility of this technique makes it an attractive option for scientists from numerous disciplines.

The molecular structures and dynamics of solids, liquids, gases, and mixtures are of critical interest to diverse scientific fields. High-temperature, high-pressure in situ MAS NMR enables detection of the chemical environment of constituents in mixed phase systems under tightly controlled chemical environments.

Nuclear magnetic resonance (NMR) spectroscopy represents an important technique to understand the structure and bonding environments of molecules. There ...

Chemistry

Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins

Intrinsically disordered proteins and intrinsically disordered regions within proteins make up a large and functionally significant part of the human proteome. The highly flexible nature of these sequences allows them to form weak, long-range, and transient interactions with diverse biomolecular partners. Specific yet low-affinity interactions promote promiscuous binding and enable a single intrinsically disordered segment to interact with a multitude of target sites. Because of the transient nature of these interactions, they can be difficult to characterize by structural biology methods that rely on proteins to form a single, predominant conformation. Paramagnetic relaxation enhancement NMR is a useful tool for identifying and defining the structural underpinning of weak and transient interactions. A detailed protocol for using paramagnetic relaxation enhancement to characterize the lowly-populated encounter complexes that form between intrinsically disordered proteins and their protein, nucleic acid, or other biomolecular partners is described.

A protocol for the application of paramagnetic relaxation enhancement NMR spectroscopy to detect weak and transient inter- and intra-molecular interactions in intrinsically disordered proteins is presented.

Intrinsically disordered proteins and intrinsically disordered regions within proteins make up a large and functionally significant part of the human ...

High-Speed Magnetic Tweezers for Nanomechanical Measurements on Force-Sensitive Elements

Single-molecule magnetic tweezers (MTs) have served as powerful tools to forcefully interrogate biomolecules, such as nucleic acids and proteins, and are therefore poised to be useful in the field of mechanobiology. Since the method commonly relies on image-based tracking of magnetic beads, the speed limit in recording and analyzing images, as well as the thermal fluctuations of the beads, has long hampered its application in observing small and fast structural changes in target molecules. This article describes detailed methods for the construction and operation of a high-resolution MT setup that can resolve nanoscale, millisecond dynamics of biomolecules and their complexes. As application examples, experiments with DNA hairpins and SNARE complexes (membrane-fusion machinery) are demonstrated, focusing on how their transient states and transitions can be detected in the presence of piconewton-scale forces. We expect that high-speed MTs will continue to enable high-precision nanomechanical measurements on molecules that sense, transmit, and generate forces in cells, and thereby deepen our molecular-level understanding of mechanobiology.

Here, we describe a high-speed magnetic tweezer setup that performs nanomechanical measurements on force-sensitive biomolecules at the maximum rate of 1.2 kHz. We introduce its application to DNA hairpins and SNARE complexes as model systems, but it will be also applicable to other molecules involved in mechanobiological events.

Single-molecule magnetic tweezers (MTs) have served as powerful tools to forcefully interrogate biomolecules, such as nucleic acids and proteins, and are ...

Cryogenic Sample Loading into a Magic Angle Spinning Nuclear Magnetic Resonance Spectrometer that Preserves Cellular Viability

Dynamic nuclear polarization (DNP) can dramatically increase the sensitivity of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. These sensitivity gains increase as temperatures decrease and are large enough to enable the study of molecules at very low concentrations at the operating temperatures (~100 K) of most commercial DNP-equipped NMR spectrometers. This leads to the possibility of in-cell structural biology on cryopreserved cells for macromolecules at their endogenous levels in their native environments. However, the freezing rates required for cellular cryopreservation are exceeded during typical sample handling for DNP MAS NMR and this results in loss of cellular integrity and viability. This article describes a detailed protocol for the preparation and cryogenic transfer of a frozen sample of mammalian cells into a MAS NMR spectrometer.

Presented here is a protocol for cryogenic transfer of frozen samples into the dynamic nuclear polarization (DNP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) probe. The protocol includes directions for rotor storage prior to the experiment and directions for viability measurements before and after the experiment.

Dynamic nuclear polarization (DNP) can dramatically increase the sensitivity of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. ...

Biology

Nuclear Magnetic Resonance (NMR) Spectroscopy

Source: Laboratory of Dr. Henrik Sund&#233;n &#8211; Chalmers University of Technology

Nuclear magnetic resonance (NMR) spectroscopy is a vital analysis technique for organic chemists. With the help of NMR, the work in the organic lab has been facilitated tremendously. Not only can it provide information about the structure of a molecule but also determine the content and purity of a sample. Compared with other commonly encountered techniques for organic chemists &#8212; such as thermal analysis and mass spectrometry (MS) &#8212; NMR is a non-destructive method that is valuable when recovery of the sample is important.
One of the most frequently used NMR techniques for an organic chemist is proton (1H) NMR. The protons present in a molecule will behave differently depending on its surrounding chemical environment, making it possible to elucidate its structure. Moreover, it is possible to monitor the completion of a reaction by comparing NMR spectra of the starting material to that of the final product.
This video exemplifies how NMR spectroscopy can be used in the everyday work of an organic chemist. The following will be shown: i) preparation of an NMR sample. ii) Using 1H NMR to monitor a reaction. iii) Identifying the product obtained from a reaction with 1H NMR. The reaction that will be shown is the synthesis of an E-chalcone (3) from an aldehyde (1) and a ketone (2) (Scheme 1).1
<img alt="Scheme 1" src="/files/ftp_upload/5680/5680scheme1.jpg" /> 
Scheme 1. Synthesis of (2E)-3-(4-methoxyphenyl)-1-(4-methylphenyl)-2-propen-1-one.

NMR Spectroscopy: Principle, NMR Active Nuclei, Applications

Source: Laboratory of Dr. Henrik Sund&#233;n &#8211; Chalmers University of Technology

Nuclear magnetic resonance (NMR) spectroscopy is a vital analysis ...

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

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Hyperpolarized Xenon for NMR and MRI Applications

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

High-Pressure NMR Experiments for Detecting Protein Low-Lying Conformational States

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy

Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins

High-Speed Magnetic Tweezers for Nanomechanical Measurements on Force-Sensitive Elements

Cryogenic Sample Loading into a Magic Angle Spinning Nuclear Magnetic Resonance Spectrometer that Preserves Cellular Viability

Nuclear Magnetic Resonance (NMR) Spectroscopy