Abstract: NMR tomography permits identification of flowing matter within a closed body, as there is a reduction in signal intensity as a consequence of a saturation of the magnetization in the area of a slice that has been excited for imaging, while freshly inflowing matter has not experienced this saturation and consequently provides a stronger signal. Special excitation sequences permit either virtually complete saturation of stationary tissue, and thus particularly strong emphasis of flowing matter, or excitation of stationary and flowing matter in different zones and with differing intensities, thereby enabling very precise quantitative and even directional flow measurements to be performed.

Abstract: To eliminate homonuclear couplings along the .omega..sub.1 axis in 2D spectroscopy, a time reversal pulse (5, 6) is inserted into the pulse sequence that is generally employed for experiments of this type, which time reversal pulse divides the evolution period t.sub.1 that is required for experiments of this type into two equal portions. The time reversal pulse is intended to cause the spin moments to rotate about an angle .beta..sub.n and is preferably composed of two 90.degree. pulses, the first of which has a phase of .beta..sub.n +.phi..sub.q and the second a phase of .pi.+.phi..sub.q. The phase of the RF oscillation of the pulse that precedes the time reversal must be shifted by an angle of .beta..sub.n.

Abstract: An Ion cyclotron resonance spectrometer comprises a first cell (8) which can be evacuated to a normal high vacuum and which is coupled with means (17, 18) for ionizing a sample substance. The first cell (8) is connected with a second cell (11) via a partition wall (15) provided with a small opening (14), which second cell (11) comprises an ion trap (27, 31) located in the homogenous area of the magnet arrangement (1, 2) and adapted for determining ion cyclotron resonances. The second cell (11) can be evacuated to a superhigh vacuum. The first cell (8) comprises an area located outside the magnet arrangement (1, 2) which lies still within the stray field of the magnet arrangement and which may be provided with an additional magnet (35) so that any desired substance can be ionized therein by any suitably adapted equipment.

Abstract: A method and apparatus are proposed for homogenizing the field of a primary magnetic coil which can be energized from a primary current source and operated in a superconductive manner and short-circuited by means of superconducting switches. A profile of the uncorrected field of the primary coil is measured along an axis of the coil, and parameters for compensating fields are determined from the profile, with the compensating fields then being superimposed on the uncorrected field.

Abstract: In a procedure for recording ion-cyclotron resonance spectra or an apparatus for carrying out the procedure, gaseous ions of a sample substance in an ultrahigh vacuum are simultaneously exposed to a constant magnetic field B.sub.O and to a high frequency field which is perpendicular to it, with resonances being excited when the frequency of the alternating field corresponds to the rotational frequency of the ions which move on circular paths in the constant magnetic field. To produce gaseous ions of the sample substance, the latter is bombarded with additional gaseous, high-energy ions of a primary substance. The primary ions are produced in the measuring cell by means of an electron beam and excited to a high energy level by means of ion-cyclotron resonance (FIG. 2).

Abstract: For recording three-dimensional nuclear magnetic resonance spectra the nuclear spin-system must be excited by three 90.degree. pulses, with variation of the pulse intervals t.sub.1 and t.sub.m. Instead of varying the two pulse intervals separately, which would be required for recording the two time dimensions defined by t.sub.1 and t.sub.m, the mixing time t.sub.m is simultaneously varied proportionally to the evolution period each time the measurement is repeated with a varied evolution period t.sub.1, so that t.sub.m =.kappa.t.sub.1. K is so selected that the interesting mixing time period is completely covered by the predetermined number of measurements taken with different evolution times. The variation of t.sub.m is reflected by the shape of the resonance lines and can be determined also by reverse transformation of the individual resonance lines into the time domain. A spectrometer for carrying out this method may conveniently be adapted to permit setting of the pulse interval t.sub.

Abstract: In recording two-dimensional nuclear magnetic resonance spectra, J cross peaks which hinder the interpretation of the spectragram and mask cross peaks of incoherent exchange processes or transfers are eliminated by one of two methods. In the first method, for each repetition of a measurement with an evolution period t.sub.1 between the first and second of two successive 90 degree pulses, the interval between the second and third 90 degree pulse (mixing time t.sub.m) is varied systematically in proportion to the evolution period. The two-dimensional spectra obtained is subjected to triangular multiplication or symmetrization so that all peaks which do not possess counterparts at the mirror symmetry positions of the main diagonal are eliminated. In the second method, the mixing time is kept constant and a 180 degree pulse is inserted between the second and third 90 degree pulse with a varying interval t.sub.p between the 180 degree pulse and the second 90 degree pulse for each repetition of a measurement.

Abstract: In the calibration of ion cyclotron resonance spectrometers there may be used the first upper sideband of the resonance frequency of known sample substances because it was found that the frequency of the first upper sideband is approximately equal to the true cyclotron resonance frequency .omega..sub.c =(q/m)B. If only one line is available for the calibration, the frequency .omega..sub.R of the first upper sideband is set equal to the true cyclotron resonace frequency .omega..sub.c in the relation ##EQU1## which is used for calibration. If multiple lines are available, a more exact calibration is possible by using the relation ##EQU2## where .omega..sub.cor is a correction frequency. The effective resonance frequency .omega..sub.eff is separated from the upper sideband by a value .DELTA..omega. which, in a good approximation, is independent of m/q.

Abstract: A method for the recording of spin resonance spectra, in which the spins of a nuclear species of a sample located in a magnetic field are excited by a pulsed rf signal and the relaxation oscillations of the spins are repetitively sampled and recorded at predetermined times and in which a radio-frequency decoupling signal is irradiated upon the sample to reduce coupling to the spins of another nuclear species, is characterized in that the decoupling signal consists of a periodic sequence of pulse groups comprising several pulses each, the pulses being so short that the frequency mixture detectable in the pulses according to the Fourier analysis covers the entire range of spin resonances of the other nuclear species.

Abstract: The invention relates to a spin resonance spectrometer comprising a sample vessel 3 for receiving a substance to be investigated, a driving device having a rotor 31 in which the sample vessel is located, and at least one pipe 45 for the supply and discharge of test substances and if necessary rinsing media. The pipe 45 projects into the sample vessel 3 coaxially with respect to its axis of rotation. The sample vessel 3 is open at both its ends and the pipe 45 is connected to one end by a fluid tight low friction bearing 43.

Abstract: A spin resonance spectrometer having a sample vessel 83 for containing substances to be examined. Pipes 92, 93 for the supply and discharge of test substances and possibly rinsing media are connected to the sample vessel, the pipe serving for supplying substances being connected to the sample vessel 83 such that the direction of movement of the substance supplied, on entering the sample vessel 83, has a component directed tangentially with respect to the sample vessel. As a result the supplied substance rotates in the sample vessel. The supply pipe 92, 93 may open substantially tangentially into the sample vessel 83, or a connecting member 184 comprising at least approximately helical channels may be located between the pipe 192 and the sample vessel 183.