Abstract: A NMR (nuclear magnetic resonance) transmit/receive switch according to some embodiments of a nuclear magnetic resonance apparatus includes receive-path and/or transmit-path superconductors, which are selectively quenched to switch the connection of an NMR radio-frequency coil between transmit and receive circuits. In the transmit state, the transmit-path superconductor is in a superconducting state while the receive-path superconductor is quenched, to isolate a receive-path amplifier from the relatively higher powers of the NMR pulses applied to the sample by the transmit circuit. In the receive state, the receive-path superconductor is in a superconducting state while the transmit-path superconductor is quenched. A DC power source is used to supply supercritical current to the superconductors to quench the superconductors.

Abstract: Test tubes with different dielectric properties are used for holding different samples/solvents within a nuclear magnetic resonance (NMR) probe of an NMR spectrometer. The test tube dielectric properties are chosen such that the overall capacitance seen by the NMR probe coils remains constant as different samples and test tubes are inserted into the probe. Samples having different solvents introduce substantially equal frequency shifts into the measurement circuitry. The disclosed systems and methods facilitate automated NMR measurements, and do not require specialized electronic or moving mechanical components for tuning compensation.

Abstract: Test tubes with different dielectric properties are used for holding different samples/solvents within a nuclear magnetic resonance (NMR) probe of an NMR spectrometer. The test tube dielectric properties are chosen such that the overall capacitance seen by the NMR probe coils remains constant as different samples and test tubes are inserted into the probe. Samples having different solvents introduce substantially equal frequency shifts into the measurement circuitry. The disclosed systems and methods facilitate automated NMR measurements, and do not require specialized electronic or moving mechanical components for tuning compensation.