This SBIR Phase I project will develop robust, high-pressure 10-mm silicon-nitride sample cells suitable for high-sensitivity high-pressure (HP) high-resolution (HR) nuclear magnetic resonance (NMR) in protein structure determination, as well as numerous other applications in materials science, super-critical fluids, and process chemistry. While HP-HR-NMR has recently been shown to have enormous analytical potential, no commercial NMR apparatus currently exists for this research. The use of hot-isostatic pressed (HIP'd) silicon nitride (Si3N4) will result in a marketable product with an order-of-magnitude increase in sensitivity compared to conventional folded glass capillaries. Initial versions will be suitable for operating pressures up to 200 MPa (2000 bar) at temperatures up to 300+C. The large inner diameter (6.00mm) in the sample region account for the order-of-magnitude increase in sensitivity, and a maximum wall thickness variation of 4 microns over a length of 25-mm in the central rf region will permit state-of-the-art lineshape and resolution (3 Hz non-spin proton at 7T). Active metal braze alloys (Ag-CuTi) will be evaluated with precision tapered joints to attach BeCu threaded fittings to each end of the sample cell for convenient sample access, pressurization, and cleaning. Total volume of compressed liquids will be only several milliliters to minimize stored energy. Internal pressurization via heating of sealed liquids, the method of choice for many applications in super-critical fluids, will be utilized during Phase I. These sample cells will be fully compatible with virtually all modern 10-mm HR-NMR probes and techniques, including triple-resonance, multi-nuclear, 2-D, solvent suppression, PFG, and MRI. Potential commercial applications exist in biochemistry (protein structure determination), and any other field utilizing NMR where high pressure is a valid concern or unexamined variable, including materials science areas like super-critical fluids process chemistry. Specifically, there are at least 3000 high-resolution spectroscopy laboratories that stand to benefit from the commercial availability of a high-pressure sample container. The compatibility of the proposed apparatus with existing HR probes will provide additional return on investment and experimental flexibility.
