Some applications of RF-gradients and excitation sculpting in NMR spectroscopy
Heikkinen, Sami (1999-05-11)
RF-gradients produced utilizing RF-field inhomogenity of conventional receiver/transmitter coil of NMR-probe can be used to mimic the effects of B0-gradients. This is done by placing long inhomogenous pulse in between two 90° pulses of appropriate phases (z-rotation cluster). B0-gradient based excitation sculpting can be converted into RF-gradient version. Selective one-dimensional TOCSY and NOESY using RF-gradient based excitation sculpting are described. In addition, non-selective two-dimensional experiments, TOCSY and NOESY, with RF-gradient based coherence selection are presented. Excitation sculpting using BIRD or BIRDR as inversion element results in isotope filter. Pre-suppression of non-13C-bound protons using RF-gradient BIRD prior to HSQC enables recording of spectrum of comparable quality to B0-gradient selected HSQC. This is beneficial for spectrometers lacking B0-gradient capabilities. Excitation sculpting using BIRDR can be used efficiently as low-pass filter in HMBC experiment. Furthermore, simultaneous elimination of protons bound to 15N and 13C can be accomplished with BIRDR based method.
- Avoin saatavuus