Download or read book Toroid Cavities as NMR Detectors in High Pressure Probes written by and published by . This book was released on 1993 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: A cylindrical toroid cavity has been developed for application as an NMR detector for high sensitivity and high resolution spectroscopy in metal vessel probes. Those probes are used for in situ investigations at high temperature and pressure. Since the transmitted r.f. field is completely confined within the torus, the cavity can be placed inside the pressurized system without magnetic coupling to the metal vessel. Resonance frequencies up to 400 MHz make the toroid cavity detector especially suited for use in 1H and 19F spectroscopy. Typically achieved static 1H linewidths, measured on CHCl3 using cavities in Be-Cu pressure vessels, are 2.0 Hz. On the basis of theoretical considerations that include the radial dependence of the r.f. field within cylindrical or circular toroid detectors, equations were evolved to predict the signal intensity as a function of the pulse width. The equations precisely describe the deviations from the sinusoidal approximation, which is generally used for signal intensities derived from Helmholtz or solenoid coils.