Systematic sources of signal irreproducibility and t1 noise in high-field NMR spectrometers

Many of the most powerful modern NMR techniques rely heavily on spectrometer stability and reproducibility. Any deficiencies in these two parameters result in such artifacts as t₁ noise in 2D NMR and spurious signals in difference spectra. One of the most important sources of error in NMR signals is the irreproducibility of the effective phases of radio-frequency pulses. In this paper a successful search for systematic sources of such errors in a modern spectrometer is described, and suggestions are given for their treatment. In the spectrometer under study, a threefold improvement in pulse reproducibility was achieved.