Abstract: According to some embodiments, a synthetic nuclear magnetic resonance (NMR) reference signal is injected into the receive path of an NMR spectrometer, after the NMR probe and before the receive amplifier. The synthetic signal is generated using a transmit path for the same channel or for a different channel than the reference signal detection channel. The reference signal is coupled from a transmit-path reference signal coupler situated before a transmit amplifier to a receive-path reference signal coupler situated between the probe and the receive amplifier. The reference signal couplers may include passive directional couplers and/or active switches. The synthetic signal samples the receive path of the system but is not substantially affected by intra-probe interactions. Using a well-defined existing NMR channel to generate the reference signal allows superior control of reference signal characteristics, and does not require a dedicated spare channel for the reference signal.

Abstract: According to some embodiments, a synthetic nuclear magnetic resonance (NMR) reference signal is injected into the receive path of an NMR spectrometer, after the NMR probe and before the receive amplifier. The synthetic signal is generated using a transmit path for the same channel or for a different channel than the reference signal detection channel. The reference signal is coupled from a transmit-path reference signal coupler situated before a transmit amplifier to a receive-path reference signal coupler situated between the probe and the receive amplifier. The reference signal couplers may include passive directional couplers and/or active switches. The synthetic signal samples the receive path of the system but is not substantially affected by intra-probe interactions. Using a well-defined existing NMR channel to generate the reference signal allows superior control of reference signal characteristics, and does not require a dedicated spare channel for the reference signal.

Abstract: According to one aspect, the low-frequency (e.g. lock channel) performance of a nuclear magnetic resonance (NMR) saddle-shaped, distributed-capacitance radio-frequency (RF) coil is improved by connecting a pair of auxiliary inductors across a plurality of leads extending upward from the coil upper ring. The upward-extending leads can be formed from the same foil as a main coil structure. The auxiliary inductors are separated from the coil window, so that magnetic susceptibility discontinuities introduced by the auxiliary inductors can be compensated for. In one embodiment, two half-toroid auxiliary inductors are positioned to form a full toroid shape. Some lost high-frequency performance can be recovered by using a split capacitance band positioned over the lower coil ring. The split capacitance band allows capacitance tuning while maintaining an RF current path close to the coil window.

Abstract: A sample probe and apparatus are provided for magnetic resonance experiments. The probe includes a coil simultaneously tunable to at least two different frequencies. The coil includes a section having a scroll configuration and defines a core into which a sample can be inserted. A multi-resonant circuit transmits RF energy to the coil at two or more different frequencies for exciting nuclei of the sample. The apparatus includes a coil having a scroll configuration. RF transmission circuitry transmits RF energy to the coil at two or more different frequencies. RF receiving circuitry receives an RF signal responsive to excitation. A coil is magnetically coupled with a sample at an RF frequency.

Abstract: An NMR probe comprises a resonator formed of two separate conducting loops disposed on opposite sides of the sample, where one loop is driven and the other floats in a preferred operating mode. Slotted shields are disposed coaxially within said loops and outside the sample with slots aligned with gaps between the loops.

Abstract: An NMR probe comprises a resonator formed of two separate conducting loops disposed on opposite sides of the sample, where one loop is driven and the other floats in a preferred operating mode. Slotted shields are disposed coaxially within said loops and outside the sample with slots aligned with gaps between the loops.

Abstract: A magnetic field generated by windings supported by a cylindrical former having axis Z is established in a desired direction forming an angle &PHgr; with respect to Z. Over an interval on Z, substantially constant value for the desired field and substantially vanishing orthogonal components are achieved by specifying the current distribution on the cylinder as a solution to field equations and then approximating said current distribution in a discrete conductor forming a plurality of anharmonic loops, nonlinearly spaced in accord with said solution.