The Toroid Cavity Autoclave for High-Pressure and Variable-Temperature in situ Nuclear Magnetic Resonance Studies
The toroid cavity autoclave (TCA) is a coaxial nuclear magnetic resonance (NMR) resonator and high-pressure autoclave for in situNMR studies, which combines the advantages of a toroid NMR detector with the features of a cylindrical metal pressure vessel. It is designed to fit within the limited space of a standard NMR narrow-bore cryomagnet and allows for recording high resolution NMR spectra during chemical reactions under high pressure. Compounds that, for example, initiate a reaction can be injected into the reactor through a nonreturn valve even if the TCA is already pressurized. The TCA is heated by a resistive, coaxial heating arrangement that does not generate any stray magnetic field in the sample volume. Current pressure and temperature capabilities are 0–300 bar and room temperature to 150?°C, respectively. With standard 200 MHz 1H NMR experiments, signal resolution of 0.55 Hz and signal-to-noise ratios comparable to those of standard NMR probes were achieved. In a further development, the TCA is optimized for gas/liquid reactions in which gaseous components are vigorously mixed with the liquid to obtain maximum reaction rates. Applications to parahydrogen induced polarization are shown, in which the nuclear spin polarization patterns show pairwise addition of hydrogen in both liquid organic solvents and in supercritical CO2.
H. G. Niessen et al., "The Toroid Cavity Autoclave for High-Pressure and Variable-Temperature in situ Nuclear Magnetic Resonance Studies," Review of Scientific Instruments, vol. 73, no. 3 I, pp. 1259, American Institute of Physics (AIP), Mar 2002.
The definitive version is available at http://dx.doi.org/10.1063/1.1447306
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© 2002 American Institute of Physics (AIP), All rights reserved.