Abstract: A monitoring cell, used to perform a measurement in an NMR spectrometer of a reaction fluid produced by a reaction vessel, has a body having inlet and outlet transport coaxial capillaries for transporting the reaction fluid between the body and the reaction vessel. Cooling lines are also positioned coaxially with the transport capillaries to transport cooling liquid between the body and the reaction vessel. The cell further has a hollow sample probe for insertion into the NMR spectrometer and a coupler section that removably connects the sample probe to the body so that the inlet transport capillary extends through the body into the interior of the sample probe and the outlet transport capillary is sealed to the sample probe to allow reaction fluid that enters the sample probe via the inlet transport capillary to exit the sample probe via the outlet transport capillary.

Abstract: A monitoring cell, used to perform a measurement in an NMR spectrometer of a reaction fluid produced by a reaction vessel, has a body having inlet and outlet transport coaxial capillaries for transporting the reaction fluid between the body and the reaction vessel. Cooling lines are also positioned coaxially with the transport capillaries to transport cooling liquid between the body and the reaction vessel. The cell further has a hollow sample probe for insertion into the NMR spectrometer and a coupler section that removably connects the sample probe to the body so that the inlet transport capillary extends through the body into the interior of the sample probe and the outlet transport capillary is sealed to the sample probe to allow reaction fluid that enters the sample probe via the inlet transport capillary to exit the sample probe via the outlet transport capillary.

Abstract: A monitoring cell, used to perform a measurement in an NMR spectrometer of a reaction fluid produced by a reaction vessel, has a body having inlet and outlet transport coaxial capillaries for transporting the reaction fluid between the body and the reaction vessel. Cooling lines are also positioned coaxially with the transport capillaries to transport cooling liquid between the body and the reaction vessel. The cell further has a hollow sample probe for insertion into the NMR spectrometer and a coupler section that removably connects the sample probe to the body so that the inlet transport capillary extends through the body into the interior of the sample probe and the outlet transport capillary is sealed to the sample probe to allow reaction fluid that enters the sample probe via the inlet transport capillary to exit the sample probe via the outlet transport capillary.

Abstract: A monitoring cell, used to perform a measurement in an NMR spectrometer of a reaction fluid produced by a reaction vessel, has a body having inlet and outlet transport coaxial capillaries for transporting the reaction fluid between the body and the reaction vessel. Cooling lines are also positioned coaxially with the transport capillaries to transport cooling liquid between the body and the reaction vessel. The cell further has a hollow sample probe for insertion into the NMR spectrometer and a coupler section that removably connects the sample probe to the body so that the inlet transport capillary extends through the body into the interior of the sample probe and the outlet transport capillary is sealed to the sample probe to allow reaction fluid that enters the sample probe via the inlet transport capillary to exit the sample probe via the outlet transport capillary.

Abstract: In a nuclear magnetic resonance probe, the sample coil is connected to the RF excitation source via transmission lines that are arranged to generate one or more nodal points at the 1H excitation frequency along their lengths and a balanced magnetic filed profile within the sample coil. Heat exchangers are then connected directly to the inner conductor of the transmission line at these nodal points. The transmission line inner conductors are in direct contact with the sample coil and efficiently cool the coil to cryogenic temperatures without interfering with the 1H resonance or RF profile.

Abstract: A nuclear magnetic resonance (NMR) probe circuit is used with a sample coil tuned to a primary frequency f1. The circuit is arranged to have a plurality of points of electric field minima at the f1 frequency. One or more additional frequencies may be coupled to the circuit at these points, without interaction with f1. The probe circuit also uses an impedance coupled between two of the minima points that affects the frequency response at the additional frequency or frequencies, without affecting the frequency response at f1. The impedance may be made adjustable to allow tuning of the relative frequency resonances.

Abstract: A flow-through sample container, or flow cell, according to the present invention resides with the channel of magnetic resonance probe without being fixed thereto. The flow cell is removable from the spectrometer while leaving the probe in place, allowing easy cleaning of the probe channel and replacement of the flow cell. An insertion tool that houses the flow cell may be used to safely introduce it to the probe. Input and output capillaries serve as fluid pathways for fluid samples entering and leaving the flow cell, respectively. These capillaries may be connected to the flow cell with a manually operable connector, allowing easy disconnection of the flow cell from the input and output conduit. The capillaries enter through different ends of the spectrometer bore, so that the fluid samples flow enter one end of the spectrometer and exit through the other.

Abstract: A circuit for a nuclear magnetic resonance probe uses three resonators to create resonances intermediate to the resonator resonant frequencies. The circuit is particularly useful for creating magnetic fields for two closely spaced high frequencies, such as those used for the excitation of 1H and 19F. The resonators are arranged in a parallel combination, or the electrical equivalent thereof, with input ports connected to it for inputting the desired high frequency resonances. Admittance inverters may be used to provide isolation between the input ports. Some of the resonators and the admittance inverters may be transmission lines. The transmission lines may have additional ports for additional input signals of lower frequencies located at null points for the frequencies of the signals coupled to the primary input ports. Adjustable dielectric components in the resonator transmission lines may be used for tuning purposes.

Abstract: A method of reducing radiation damping during free induction decay in NMR measurements of samples having a narrow line width uses the active switching of the quality factor value of the coil circuit of an NMR detection probe. After application of an excitation pulse to the sample, data acquisition is accomplished in periodic samples. The Q of the coil circuit is set to a high value while each sample is being taken, but is reduced significantly in between samples by detuning the coil circuit. Minimization of the high-Q state of the coil circuit and maximization of the difference between the high Q value and the low Q value greatly decrease the detrimental effects of radiation damping on free induction decay. The coil circuit Q is modified automatically by the application of a Q switching signal generated by a controller, such as a computer which controls other aspect of the NMR experiment.

Abstract: A nuclear magnetic resonance cross polarization probe uses a dual-coil arrangement in which a single-turn inner coil is surrounded by a solenoid coil. The inner coil is tuned to the frequency of a relatively high Larmor frequency nuclei type, such as proton. The solenoid coil is tuned to a lower Larmor frequency nuclei type. An inner sample region surrounded by the inner coil has a first magnetic field component induced by an electrical signal at the relatively high frequency in the inner coil. An electrical signal at the lower frequency is input to the solenoid coil and results in the generation of a magnetic field alternating at the lower frequency. This field induces a current in the inner coil at the lower frequency that, in turn, induces a magnetic field component in the inner region at the lower frequency.

Abstract: B.sub.1 (RF) gradient echo pulse sequences are combined with frequency-selective pulse sequences to selectively suppress a solvent resonance signal by preventing the formation of an echo for the solvent resonance, while allowing the formation of an echo for the sample resonances under study. The RF gradient pulses may be planar or radial pulses. A pulse sequence for suppressing a solvent resonance signal in NMR experiments comprises a pair of (RF) gradient pulses which sandwich a selective inversion pulse sequence. In accordance with one embodiment of the invention, the RF gradient pulses are anti-symmetric (have opposite phase) and the selective inversion pulse sequence comprises a homogeneous frequency-selective inversion pulse, such as a .pi. pulse, applied in time between the two RF gradient pulses.

Abstract: A composite RF pulse is created from a sequence of conventional homogeneous RF pulses and conventional gradient RF pulses and the composite pulse generates a gradient magnetic field with a spatially varying amplitude, but a spatially independent phase. In one embodiment of the invention, the pulse sequence consists of four conventional gradient RF pulses interspersed with two conventional homogeneous RF pulses. In another embodiment of the invention, a conventional gradient RF pulse is combined with a conventional homogeneous RF pulse and the pulse pair is repeated in order to generate an effective magnetic field with a spatially varying amplitude, but a spatially independent phase.

Abstract: Coherence transformation selectivity is improved by using combinations of homogeneous RF pulses and "radial" RF pulses that have a uniform RF field strength throughout the sample, but whose phase (relative to the detection coil phase) has a spatial dependence such that all possible phase differences are equally represented throughout the sample. The use of radial pulses allows the spin coherences in the sample to evolve in spatial waves and the observation, or suppression, of a given coherence can be selected by using a receiver coil which has a predetermined symmetry relative to the symmetry of the spatial wave.

Abstract: An NMR probe is designed to generate both a homogeneous RF field over the sample volume and, alternatively, a "radial" field comprising two orthogonal gradient fields generated simultaneously in the transverse plane or a linear gradient field. The homogeneous field is generated by means of a known homogeneous coil construction, such as a Helmholtz coil or modified Helmholtz coil. The radial field can be generated by means of an inverted Helmholtz coil, either modified or unmodified, and the linear field can be generated by a Golay type coil, which coils are positioned coaxially with the homogeneous coil. The two coils are connected in parallel to the RF signal generator and switching can be accomplished either by means of an active switch or by detuning one of the coil resonant circuits when the other coil is in use.

Abstract: A composite RF pulse for NMR experiments is created by applying to a sample a radial pulse followed by a .pi. homogeneous pulse. The radial pulse has a uniform RF field strength throughout the sample and a phase relative to the detection coil phase with a spatial dependence such that all possible phase differences are equally represented throughout the sample. The composite pulse converts the radial RF pulse into a spatially-varying z rotation. The creation of a spatially-varying composite z pulse based on a radial pulse allows for a simple and direct application of a radial pulse in a manner analogous to many known B.sub.0 gradient NMR experiments (such as multiple-quantum filters, quadrature detection, and solvent suppression).