Abstract: Apparatus is provided for coupled liquid chromatography and nuclear magnetic resonance (NMR) spectroscopy measurements. The apparatus includes a liquid chromatograph, an intermediate storage device for intermediately storing of components of a probe eluent and an NMR spectrometer. Selected intermediately stored components are fed to an NMR measurement unit. The intermediate storing device includes a number of capillary tubes, which are switchable by an automatically controlled valve arrangement for selectively receiving and delivering desired eluent components.

Abstract: In a magnet system with two coil systems of different mean diameter arranged coaxially with respect to the longitudinal axis of the system defined by the direction of the field in the homogeneity region, which are rotationally symmetrical and are arranged symmetrically about the transverse median plane of the system perpendicular to the longitudinal axis and can carry exciting currents which result in overlapping magnetic fields that compensate, at least approximately, for the dipole fields of the two coil systems, an operating mode selector switch device (22) configured as a superconducting network is provided, by means of which the magnet system (10) can also be switched, as an alternative to the operating mode which provides considerable dipole-field compensation in the outer space of the magnet system (10), to that operating mode in which the magnetic fields generated by the two coil systems (11 and 12) at the center thereof are aligned in the same direction. In a special configuration, the ratio B.sub.

Abstract: The invention concerns head for flowthrough NMR spectroscopy in which there is provided, in the interior of a vessel, a replaceable quartz cuvette which can be separated from the vessel, and eluent inflow and outflow tube, and a measurement coil, and which has end sections which seal with respect to the vessel.The parts constituting the vessel, namely a cylindrical glass casing, a cover, and a base, as well as the replaceable quartz cuvette, can be clamped together with a simple clamping device in such a way that the sample head according to the invention can also be used for high pressure, such as those which occur with SFC (supercritical fluid chromatography) NMR measurements.

Abstract: A superconductive magnet coil arrangement for generating a homogeneous magnetic field in a volume under examination, comprising a magnet coil having two first windings of a superconductive wire which are disposed adjacent the ends of the magnet coil and which are supported on a hollow supporting body, and comprising further at least one additional winding of a superconductive wire which is arranged in the area between the first windings and which is supported by the supporting body, is characterized by the fact that at least one of the additional windings is arranged on a winding core mounted on the supporting body and the fixation securing the winding against axial displacement occupies an area in length of the winding core shorter than the length of the winding arranged on the winding core. It is achieved in this manner that the pressure produced by Lorentz forces in the supporting body is kept off the rest of the winding.

Abstract: A sample head for performing nuclear magnetic resonance measurements on a first kind of nuclei (.sup.1 H) and, further, on a second (.sup.15 N) or a third (.sup.31 P) kind of nuclei within a magnetic field (B) is disclosed. A measuring coil coacts with a sample under analysis and generates a nuclear magnetic resonance within the sample or receives a nuclear magnetic resonance signal from the sample. Terminals are provided for transmitting to or receiving from the measuring coil high-frequency signals having frequencies corresponding to the particular nuclear magnetic resonance frequency of the specific kinds of nuclei (.sup.1 H, .sup.15 N, .sup.31 P), respectively. A high-frequency line is connected to the measuring coil at one end thereof. The line has an electric length which is an integer multiple of a quarter wavelength corresponding to the first, higher frequency.

Abstract: Winding arrangements for cryomagnets have a winding of superconducting wire (12) connected in parallel to a winding of normally conducting wire (11) which, in the event of a quench, conducts the operating current and mechanically stabilizes the winding arrangement. Independently of this, the size of such a winding arrangement depends primarily on the tensile forces exerted on the wires and on the modulus of elasticity of the material of the wire. The size of such a winding arrangement is a significant factor in its cost and should therefore be reduced. According to the invention, the winding arrangement has a plurality of groups (17) arranged in radially repetitive layers inside the winding section, in which each winding of superconducting wire surrounds windings of a normally conducting wire and windings of steel wire or of a wire with a high modulus of elasticity.

Abstract: An NMR spectrometer is utilized in order to determine the magnetic susceptibility of a sample, in which, by means of the sample, a change in the homogeneous magnetic field in the region of a probe substance is effected and the change in the spectrum of the probe substance which is thereby caused is observed. A method known in the art is based on the modulation of the resonance frequency which occurs when the probe substance is caused to rotate about an axis perpendicular to the direction of the magnetic field. The application of this method encounters difficulties with spectrometers whose probe volume is penetrated axially by the magnetic field. In accordance with the invention, by means of the sample (14), a change is produced in the magnetic field along the probe axis in a sample substance (12) preferentially positioned along the direction of the magnetic field.

Abstract: In an NMR magnet system for generating a highly homogeneous magnetic field of high field strength, with at least one superconducting magnet coil which is arranged in a first chamber of a cryostat in supercooled liquid helium at a temperature of less than 4.2K, with the cryostat having at least one further chamber containing liquid helium that is essentially at atmospheric pressure with a temperature of approximately 4.2K, the first chamber is connected to the further chamber in such a way that the supercooled liquid helium located in the first chamber is also essentially at atmospheric pressure. A refrigerator with which the liquid helium can be cooled to a temperature T<<4.2K, especially to T.apprxeq.1.8-2.3K, is provided in the first chamber.

Abstract: A resonator is provided for electron spin resonance spectroscopy. The resonator comprises walls defining a cavity. In the cavity, a predetermined oscillation mode of a preselectable frequency, in particular in the Q band, is capable of propagating. The walls are provided with an opening for irradiating a radiation, in particular light rays. The cavity has a cylindrical shape. An oscillation mode of the type TE.sub.01n is excited, with n being greater than one. The opening is configured as an annular slot extending substantially all around the cylindrical jacket, which defines the cavity, in a radial plane at a distance of m L/4 from a radial end wall delimiting the cavity, and m is an odd number and greater than one (FIG. 2).

Abstract: A magnet winding in a air coil configuration with windings made from conducting elements which surrounds a magnetic field axis and is wound in at least two layers with at least one layer transition, is characterized in that, in an angular region about the magnetic field axis which includes a layer transition, the radial separation from the magnetic field axis of at least the radially innermost winding of a respective layer is less than that in the other angular region. In this manner, it is, to a large extent, possible to compensate for the magnetic field breach resulting from the "thinning" of the effective active conducting elements of the innermost winding in the region of the layer transition.

Abstract: In a method and an apparatus for the precooling of a helium tank of a cryostat, in particular an optical cryostat with optical components in the helium tank, or an NMR cryostat, or a medical NMR cryostat for magnet resonance imaging, which accepts a superconducting magnet coil, a simple and cost effective precooling is achieved in that liquid nitrogen is directed out of a storage container under small overpressure via a conduit through an opening in the helium tank of a cryostat into a heat exchanger arranged in the helium tank and therefrom, by way of an opening, out of the cryostat and, finally, into a collecting container, in particular, into a nitrogen tank surrounding the helium tank.

Abstract: An infrared Fourier transformation spectrometer comprising a non-linear analog-to-digital converter device having at least one amplifier and one sample and hold circuit connected downstream thereof, as well as an an analog-to-digital converter following the latter, wherein an input signal to be converted is to be supplied to one input of the amplifier and the gain of the input signal is a function of the magnitude fo the input signal, and wherein the output signal of the analog-to-digital converter is evaluated giving regard to the respective gain, is characterized by the fact that at least two analog-to-digital converters are provided whose outputs are connected to a first controllable switching arrangement for supplying selectively the output signals of one of the said analog-to-digital converters to another evaulation means and that the input signal is supplied to each of the said analog-to-digital converters amplified by a different amplification factor.

Abstract: The invention relates to an apparatus for measuring chemical and/or physical reaction sequences by nuclear magnetic resonance spectrometry and comprises a reaction path (1), a nuclear magnetic resonance spectrometer (2) and at least one reaction chamber (10) which is located in the reaction path, wherein means are provided for feeding at least the reaction product from the reaction chamber (10) to the nuclear magnetic resonance spectrometer (2). According to the invention, at least reaction chamber (10) and its reagent supply and discharge lines (5 to 7) are mounted, by means of a mounting angle (29), on the same head housing (9) on the latter's end which projects from the spectrometer magnet bore, in the stray field of the spectrometer magnet.

Abstract: A probehead for a nuclear magnetic resonance spectrometer is disclosed comprising a coil structure defining an axis and having a first, a second, and a third solenoid sub-coil. The sub-coils are switched in parallel and are fed from a common high-frequency source. Adjacent sub-coils are wound in an opposite winding direction. A sample holder is arranged within the center of the middle sub-coil.

Abstract: A magnet system to generate a static, uniform magnetic field in the examination chamber of a nuclear spin tomograph has a pair of outer field coils (1a, 1b) arranged on a common axis (a) at a mutual axial distance (g.sub.1) and a pair of inner field coils (2a, 2b) coaxial with the outer ones which are also equal to each other, in which both pairs of coils are arranged symmetrically to a central plane (E) perpendicular to the common axis (a). The axial distance (g.sub.1) between the outer field coils (1a and 1b) is 40 to 60% of their inside diameter (da.sub.2). The axial distance (g.sub.2) between the inner field coils (2a and 2b) is, with a maximum deviation of 15%, equal to that (g.sub.1) between the outer coils (1a and 1b). The magnet system forms an almost eight-order coil system and there is at least one transverse access aperture running across the direction of the uniform magnetic field and between the inner field coils (2a, 2b).

Abstract: A method serving for recording spin resonance spectra of test samples having at least two groups (CH.sub.3, CH) of nuclei of the same kind and of substantially identical chemical shift, comprises the step of suppressing the signal of the second group (CH) for the purpose of obtaining an isolated image of the signal of the first group (CH.sub.3). To this end, a pulse sequence of four r.f. pulses, preferably 90.degree. r.f. pulses (10, 12, 13, 14), are irradiated upon the sample. The first r.f. pulse (10) is a soft pulse, selective for the nuclei of the first group (CH.sub.3). The second r.f. pulse (12) is a soft pulse, selective for the nuclei of the second group (CH), and causes the magnetizations of the nuclei of the first group (CH.sub.3) and of the second group (CH) to be transferred, at least in part, to a state of multiple-quantum coherence. Immediately following the second r.f. pulse (12) the third r.f.

Abstract: In order to take NMR-spectrograms, it is necessary that the spins of the sample be arranged in a homogeneous magnetic field. For that purpose, NMR-spectrometers have a magnet arrangement (2) in the magnetic field of which is arranged a sampling head (5). When the spin-lattice-relaxation time T.sub.1 of substances to be examined lies in the range of hours, the spectrometer is unusable for hours due to the necessary prepolarization of the sample. The invention is aimed at solving this problem. A sample magazine (11) is arranged in the magnetic field generated by the magnet arrangement (2). It offers the possibility of exposing a larger number of samples to the magnetic field of the magnet (2) while simultaneously carrying out measurements. Since measurements of samples having long spin-lattice-relaxation times T.sub.

Abstract: A multi-experiment magnetic-resonance instrument such as a programmable pulse/Fourier-transform nuclear-magnetic-resonance ("NMR") spectrometer, an electron-paramagnetic-resonance spectrometer, or a magnetic resonance tomographic imaging device, capable of performing any one of a plurality of magnetic-resonance measurement sequences selected by a user and comprising: a magnet for generating a magnetic field; a probe having radio-frequency coupling circuitry positionable in the magnet; a radio-frequency generator/transmitter connected to the coupling circuitry of the probe; a radio-frequency receiver/digitizer connected to the coupling circuitry of the probe; a digitized-signal averager/processor connected to the receiver/digitizer; a programmable instrument controller having measurement-sequence control-program storage; a barcode reader connected to the instrument controller; and at least one measurement-sequence-selection barcode table having a plurality of barcode-encoded measurement-sequence data words arr

Abstract: Optical high-pressure transmission cells of the type used, for example, for SFC-FTIR, comprise a pressure-resistant housing part with two intersecting bores, one of them forming a fluid passage and the other one forming a light transmission path. The bore forming the light transmission path is provided with inserted windows. There is a demand in infrared spectroscopy, for supercritical fluid chromatography, for particularly pressure-resistant cells of simple design, which demand has not been satisfied heretofore. In the case of the proposed measuring cell, the windows are designed as stepped windows having central cylindrical neck portions engaging the bore serving as a light transmission path so that the chamber is delimited by end faces of the neck portions. Sealing is effected by O-rings.

Abstract: A test head for NMR spectrometers comprises an rf coil mounted on a carrier pipe and a shielding which extends over at least one section of two parallel conductors extending in the axial direction of the carrier pipe. In order to improve the effect of shielding, the shielding is connected, in an electrically conductive manner, to a turn section of the rf coil which contains a cold point. The shielding is thereby maintained at a fixed neutral potential, relative to the rf voltage supplied, with the result that no fields impairing the measuring accuracy and resolution of the spectrometer can any longer exist in the shielded area. The shielding may be connected directly to one turn section of the coil, for example by soldering.