Method of 2D-NMR correlation spectroscopy with double quantum filtration followed by evolution of single quantum transitions
A method of 2-dimensional nuclear magnetic resonance (2D-NMR) correlation spectroscopy, comprises a pulse sequence with the following steps: excitation of double quantum coherence; immediate reconversion to single transition single quantum coherence; evolution of the set of single transitions; mixing with zero quantum mixing Hamiltonian; and signal detection. The method can achieve an improved sensitivity, has a transition selectivity and suppresses diagonal peaks.
1. A method of 2-dimensional nuclear magnetic resonance (2D-NMR) correlation spectroscopy having a pulse sequence comprising the following steps:
a) exciting a double quantum coherence;
b) immediately reconverting to single transition, single quantum coherence;
c) evolving a set of single transitions;
d) mixing with a zero quantum mixing Hamiltonian; and
e) detecting signals.
2. The method of claim 1 , wherein during step b), a conversion to a single transition at each of chemical shifts of two coupled spins is effected.
3. The method of claim 1 , wherein, in step b), a double quantum re-conversion is detuned with a first pulse having a flip angle other than 45°, a reduced flip angle or a flip angle of 20°-30°.
4. A method of 2D-NMR correlation spectroscopy having a pulse sequence comprising the following steps:
a) exciting a double quantum coherence;
b) immediately reconverting using a 90° pulse;
c) evolving a set of anti-phase single quantum transitions;
d) mixing with a zero quantum mixing Hamiltonian; and
e) detecting signals.
5. The method of claim 1 , wherein in step d), isotropic mixing is effected.
6. The method of claim 5 , wherein in step d), isotropic mixing is effected with sequences optimized for chemical shift bandwidth and/or coupling bandwidth.
7. The method of claim 1 , wherein, in step d), a cascade of two bilinear rotations is applied.
8. The method of claim 7 , wherein a cascade of two bilinear rotations includes pulse contraction.
9. The method of claim 1 , wherein a π pulse is applied just before or right after step d).
10. The method of claim 1 , wherein suitable offset compensated pulses or offset compensated groups of pulses are employed.
11. The method of claim 1 , wherein the pulse sequence is adapted for indirect detection.
12. The method of claim 1 , wherein C-13 nuclei are used.
13. The method of claim 1 , wherein solution samples are used.
14. Te method of claim 1 , wherein solid state samples are used or are used while applying magic angle spinning (MAS) or Si-29 and/or C-13 nuclei are used.
15. The method of claim 1 , wherein rare spin-1/2 systems are used.
16. The method of claim 1 , wherein spin-1-systems in ordered phases, H-2, Li-6, or N-14 are used.
17. The method of claim 1 , wherein the method is adapted to generate magnitude mode spectra or pure phase spectra.