Method for recording two-dimensional nuclear magnetic resonance spectra and a device for carrying out the same

Claim 1

A method for recording two-dimensional nuclear magnetic resonance spectra of a nuclear spin system having spins between which a coupling exists, said coupling causing a shift of the resonance frequency of said spins, in which method said nuclear spin system is excited by three successive 90° pulses and an interferogram obtained after application of the third 90° pulse is subjected to Fourier analysis, in which further a plurality of such measurements is taken with different intervals between the first and the second 90° pulses known as the evolution period t 1 and the resulting different amplitudes of the resonance lines obtained by the said Fourier analysis are stored as instantaneous values of an additional interferogram and subjected to a second Fourier analysis, and in which simultaneously with each repetition of the measurement with a varied evolution period t 1 the time interval between the second and the third 90° pulses, which is known as the mixing time t m , is systematically varied by increments covering the domain defined by the period of the frequency shifts caused by said couplings, characterized in that starting from an initial value t m0 , the mixing time t m is varied proportionally to the evolution period t 1 whereby t m =t m0 +χt 1 so that with an envisaged number of n measurements the time variation of the mixing time t mn -t m0 , which is relatively small compared to t m0 , is substantially equal to the period of frequency displacements caused by said coupling, and in that the two-dimensional spectrum thus obtained is subjected to the techniques of triangular multiplication or symmetrization whereby all peaks which do not possess counterparts at the mirror symmetry position with respect to a main diagonal are eliminated.

Claim 2

A method for recording two-dimensional nuclear magnetic resonance spectra of a nuclear spin system having spins between which a coupling exists, said coupling causing a shift of the resonance frequency of said spins, in which method said nuclear spin system is excited by three successive 90° pulses and an interferogram obtained after application of the third 90° pulse is subjected to Fourier analysis, in which further a plurality of such measurements is taken with different intervals between the first and the second 90° pulses known as the evolution period t 1 and the resulting different amplitudes of the resonance lines obtained by the said Fourier analysis are stored as instantaneous values of an additional interferogram and subjected to a second Fourier analysis, and in which simultaneously with each repetition of the measurement with a varied evolution period t 1 the time interval between the second and the third 90° pulses, which is known as the mixing time t m , is systematically varied by increments covering the domain defined by the period of the frequency shifts caused by said couplings, characterized in that starting from an initial value t m0 , the mixing time t m is varied proportionally to the evolution period t 1 whereby t m =t m0 +χt 1 so that with an envisaged number of n measurements the time variation of the mixing time t mn -t m0 , which is relatively small compared to t m0 , is substantially equal to the period of frequency displacements caused by said coupling, and in that the two-dimensional spectrum thus obtained is subjected to the techniques of triangular multiplication or symmetrization whereby all peaks which do not possess counterparts at the mirror symmetry position with respect to a main diagonal are eliminated.

Claim 3

A method for recording two-dimensional nuclear magnetic resonance spectra of a nuclear spin system having spins between which a coupling exists, said coupling causing a shift of the resonance frequency of said spins, in which method said nuclear spin system is excited by three successive 90° pulses and an interferogram obtained after application of the third 90° pulse is subjected to Fourier analysis, in which further a plurality of such measurements is taken with different intervals between the first and the second 90° pulses known as the evolution period t 1 and the resulting different amplitudes of the resonance lines obtained by the said Fourier analysis are stored as instantaneous values of an additional interferogram and subjected to a second Fourier analysis, and in which finally a 180° pulse is inserted between the second and the third 90° pulses and the interval t p between the 180° pulse and the second 90° pulse is systematicaly varied, with each repetition of the measurement with another evolution period t 1 , by increments covering the domain defined by the period of the frequency shift caused by said couplings, characterized in that the time interval t p is systematically varied, starting from an initial value t p0 and in proportion to the evolution period t 1 whereby t p =t p0 +χt 1 , so that with an envisaged number of n measurements the time variation of the positioning time t pn -t p0 , which is relatively small compared to t m , is in the range of the period of frequency displacements caused by said coupling, and in that the two-dimensional spectrum thus obtained is subjected to the techniques of triangular multiplication or symmetrization whereby all peaks which do not possess counterparts at the mirror symmetry position with respect to a main diagonal are eliminated.

Claim 4

A method for recording two-dimensional nuclear magnetic resonance spectra of a nuclear spin system having spins between which a coupling exists, said coupling causing a shift of the resonance frequency of said spins, in which method said nuclear spin system is excited by three successive 90° pulses and an interferogram obtained after application of the third 90° pulse is subjected to Fourier analysis, in which further a plurality of such measurements is taken with different intervals between the first and the second 90° pulses known as the evolution period t 1 and the resulting different amplitudes of the resonance lines obtained by the said Fourier analysis are stored as instantaneous values of an additional interferogram and subjected to a second Fourier analysis, and in which finally a 180° pulse is inserted between the second and the third 90° pulses and the interval t p between the 180° pulse and the second 90° pulse is systematicaly varied, with each repetition of the measurement with another evolution period t 1 , by increments covering the domain defined by the period of the frequency shift caused by said couplings, characterized in that the time interval t p is systematically varied, starting from an initial value t p0 and in proportion to the evolution period t 1 whereby t p =t p0 +χt 1 , so that with an envisaged number of n measurements the time variation of the positioning time t pn -t p0 , which is relatively small compared to t m , is in the range of the period of frequency displacements caused by said coupling, and in that the two-dimensional spectrum thus obtained is subjected to the techniques of triangular multiplication or symmetrization whereby all peaks which do not possess counterparts at the mirror symmetry position with respect to a main diagonal are eliminated.