Broadband NMR with random-window noise excitation.

Abstract

Motivated by recent generations of compact portable and benchtop NMR instrumentation, we present a new method for the acquisition of broad bandwidth NMR spectra using stochastic excitation. The new method decouples the spectral width from the durations of the excitation pulses and ring-down delays, allowing the receiver bandwidth to be arbitrarily large. This allows low-power, low-flip-angle pulses to be used to acquire broad-band NMR spectra such as wideline powder patterns from solids. The new method divides experimental time into distinct "pulse" and "acquire" blocks that are interleaved according to a pseudo-random noise sequence and combined with a second sequence for phase modulation. The method is described mathematically, and is demonstrated with both liquids and wide-line solids experiments.