Abstract: A nuclear magnetic resonance (NMR) method for singlet-state exchange NMR-spectroscopy comprises steps of excitation of single-quantum in-phase coherences, generation of single-quantum anti-phase coherences, excitation of zero-quantum coherences ZQx and/or longitudinal two-spin order 2IzSz (=“ZZ order”) using a ?/4 pulse, reversal of the sign of the zero-quantum coherences ZQx under the effect of the difference of the chemical shifts of the examined spins, transformation of the zero-quantum coherences ZQx and/or longitudinal two-spin ZZ order into singlet-state populations by means of RF irradiation during a mixing period ?m, reconversion of the singlet-state populations remaining at the end of the mixing period ?m into zero-quantum coherences ZQx and/or ZZ order, reversal of the sign of the zero-quantum coherences ZQx under the effect of the difference of the chemical shifts of the examined spins, and reconversion of zero-quantum coherences ZQx and/or ZZ order into single-quantum anti-phase coherences.

Abstract: A nuclear magnetic resonance (NMR) method for singlet-state exchange NMR-spectroscopy comprises steps of excitation of single-quantum in-phase coherences, generation of single-quantum anti-phase coherences, excitation of zero-quantum coherences ZQx and/or longitudinal two-spin order 2IzSz (=“ZZ order”) using a ?/4 pulse, reversal of the sign of the zero-quantum coherences ZZQx under the effect of the difference of the chemical shifts of the examined spins, transformation of the zero-quantum coherences ZZQx and/or longitudinal two-spin ZZ order into singlet-state populations by means of RF irradiation during a mixing period ?m reconversion of the singlet-state populations remaining at the end of the mixing period ?m into zero-quantum coherences ZZQx and/or ZZ order, reversal of the sign of the zero-quantum coherences ZZQx under the effect of the difference of the chemical shifts of the examined spins, and reconversion of zero-quantum coherences ZZQx and/or ZZ order into single-quantum anti-phase coherences.

Abstract: A method for obtaining NMR (=nuclear magnetic resonance) spectra of quadrupolar nuclei having spin I>½ using magic angle spinning (=MAS) in solid powders and transfer of coherences from a neighboring nucleus with spin S= 1/2 to single- or double-quantum transitions of quadrupolar nuclei having spin I>½, is characterized in that the transfer of coherences occurs through a combination of scalar and residual dipolar splittings. With the inventive method improved NMR-spectra can be obtained from which parameters can be extracted, which can be related to the structure and internal dynamics of solids containing the quadrupolar nuclei.

Abstract: A method for obtaining NMR (=nuclear magnetic resonance) spectra of quadrupolar nuclei having spin l>½ using magic angle spinning (=MAS) in solid powders and transfer of coherences from a neighboring nucleus with spin S= 1/2 to single- or double-quantum transitions of quadrupolar nuclei having spin l>½, is characterized in that the transfer of coherences occurs through a combination of scalar and residual dipolar splittings. With the inventive method improved NMR-spectra can be obtained from which parameters can be extracted, which can be related to the structure and internal dynamics of solids containing the quadrupolar nuclei.

Abstract: A pulsed field gradient NMR (=nuclear magnetic resonance) method using stimulated echoes for determining the translational isotropic or anisotropic diffusion coefficient of a molecule or supra-molecular assembly or the flow rate and direction of fluids containing such molecules is characterized in that the molecule or supra-molecular assembly contains one or several isotopes (X) of non-zero nuclear spin other than protons having longitudinal relaxation times T1(X) that are longer than the longitudinal relaxation times T1(H) of the protons, and that the information about the localization of the molecule or supra-molecular assembly during the diffusion or flow interval is temporarily stored in the form of longitudinal magnetization of said isotope or isotopes. Thus, the determination of translational diffusion coefficients or flow rates of supra-molecular assemblies or molecules with short T1(H) values, in particular of supra-molecular assemblies or molecules with M≧50 kDa is accomplished.

Abstract: A pulsed field gradient NMR (=nuclear magnetic resonance) method using stimulated echoes for determining the translational isotropic or anisotropic diffusion coefficient of a molecule or supra-molecular assembly or the flow rate and direction of fluids containing such molecules is characterized in that the molecule or supra-molecular assembly contains one or several isotopes (X) of non-zero nuclear spin other than protons having longitudinal relaxation times T1(X) that are longer than the longitudinal relaxation times T1(H) of the protons, and that the information about the localization of the molecule or supra-molecular assembly during the diffusion or flow interval is temporarily stored in the form of longitudinal magnetization of said isotope or isotopes. Thus, the determination of translational diffusion coefficients or flow rates of supra-molecular assemblies or molecules with short T1(H) values, in particular of supra-molecular assemblies or molecules with M≧50 kDa is accomplished.

Abstract: Methods and apparatus for broadband decoupling in nuclear magnetic resonance with chirp and other RF pulses are disclosed. Such methods may include the step of positioning the sample in a static magnetic field. Additional steps may define a first cycle of pulses, such as chirp pulses, wherein at least two of the pulses have a different initial phase angle from each other and may define a second cycle of pulses wherein at least two of the pulses in the second cycle have an initial phase angle different from the initial phase angles of the pulses in the first cycle. Further steps may repeatedly generate a supercycle of the first and second cycles to produce pulses for inverting the longitudinal magnetization in the sample and may also detect the signals emitted by the sample in response to inversion of the longitudinal magnetization. Alternatively, the chirp pulses in the first and second cycles may be defined to sweep a bandwidth of 100 kHz or more.

Abstract: It is shown that is is possible to inhibit the transfer of magnetization in a chemically exchanging system with several sites in dynamic equilibrium, so that the forward and the backward reaction rates involving two selected species can be studied without being significantly perturbed by other exchange processes. This can be achieved either by selective inversion of the magnetization of the two chosen sites in the course of the reaction interval, or alternatively by inversion of all other sites in the network of exchanging nuclei that one wishes to "decouple" from the selected pair of interest.

Abstract: A method for exciting transverse magnetization by irradiating a nuclear spin system subjected to a constant magnetic field with a frequency-modulated rf-pulse ("chirp"-pulse) and with a further frequency-modulated rf-pulse (further chirp-pulse) for refocusing the magnetization, is characterized in that the rf-pulse-(P1) and the further rf-pulse (P2) overlap each other in time at least partially. Thus, the duration of the pulses can be reduced.

Abstract: Frequency-modulated "chirp" pulses for exciting multiple-quantum coherences over large bandwidths can be considered as an alternative to composite pulses to combat the effects of large offsets and tilted effective fields. Refocusing of the phase dispersion of double-quantum coherence can be combined with suitable detection sequences to yield pure absorption two-dimensional double-quantum spectra. The method of symmetrical excitation and detection by time-reversal may be applied to obtain t.sub.1 -modulated longitudinal magnetization, which may then be converted into observable single-quantum coherence by a chirp echo sequence. Similar approaches can be used for many other NMR experiments involving coherence transfer.

Abstract: A method for generating a spectrum of NMR signals with rectangular characteristic in the frequency space by radiating a sequence of RF pulses onto a sample in the homogeneous magnetic field is presented. The RF pulses of the sequence are amplitude modulated and the enveloping function of the sequence consists of a superposition of bell-curve-shaped RF pulses with optimized positions of the maxima, pulse widths and peak amplitudes. The response signals, in dependence on the standardized frequency, shift, approximate virtually ideally, a rectangular function. The method is applicable with success especially in image generation for NMR tomography, in multidimensional NMR spectroscopy, as well as in volume selective NMR spectroscopy.

Abstract: A method for measuring cross-relation rates in high-resolution nuclear magnetic resonance (NMR) spectroscopy in which in a homogeneous static magnetic field B.sub.0 in a direction of a z-axis which causes alignment of longitudinal components I.sub.Z.sup.A, I.sub.Z.sup.X of magnetization vectors I.sup.A, I.sup.X of nuclei A, X during a time interval .tau..sub.m a sample substance, preferably dissolved in liquid, with nuclei A and X having different chemical shifts .OMEGA..sub.A and .OMEGA..sub.X is irradiated with a radio-frequency (rf) field and afterwards by action of a suitable rf-pulse sequence the longitudinal magnetization is transferred into a transverse magnetization creating a rf-signal received by a detector, is characterized in that the rf field is composed by at least two weak, selective component fields, the frequencies of these fields being chosen such that the magnetization vectors I.sup.A and I.sup.

Abstract: The use of 270.degree. Gaussian pulses instead of the selective 90.degree. pulses usual heretofore makes it possible, for many NMR experiments, to achieve a frequency-selective excitation of samples which is largely free from phase errors and which, consequently, does away in many cases with the need for rephasing measures which heretofore were necessary as a rule.

Abstract: In NMR pulse experiments transverse magnetization is excited by irradiating the nuclear spin system with a two pulse sequence of a first RF chirp pulse and a second RF chirp pulse, generated after a defocusing time interval .tau.. The pulse duration of the second chirp pulse is half the duration of the first pulse, and the amplitude of the second chirp pulse is approximately three times the amplitude of the first chirp pulse. The first pulse being a 90.degree.-pulse, the second pulse being a 180.degree.-pulse, a refocusing of the magnetization vectors occurs at a time .tau.'=.tau.+.tau.180.degree. after elapse of the second chirp pulse, and acquisition of the resulting echo signal is started at peak of the echo.

Abstract: Ion cyclotron resonance is an important method used in mass spectroscopy. Examinations for determining the reactions between substances by means of the two-dimensional ICR method are carried out using the following measuring sequence:P.sub.1 -t.sub.1 -P.sub.2 -T.sub.m -P.sub.3 -t.sub.2,wherein P.sub.1, P.sub.2 and P.sub.3 are rf pulses, with the rf pulses P.sub.1 and P.sub.2 having the same frequency, t.sub.1 and T.sub.m are time intervals between the pulses and t.sub.2 is the observation time following the last pulse. This measuring sequence is repeated several times while varying t.sub.1. In this manner, a plurality of induction signals recorded during the time t.sub.2 is obtained, from which then a two-dimensional spectrum is derived by transformation from the time domain into the frequency domain. The transformation from the time domain to the frequency domain can be effected by two-dimensional Fourier transformation, or with the aid of the method of maximum entropy.