A broadband nuclear magnetic resonance spectrometer: Digital phase shifting and flexible pulse programmer

Abstract

A simple, low-cost pulse nuclear magnetic resonance (NMR) spectrometer is described. There are two key features of the instrument: (1) all radio frequency phase shifting is done digitally with a new-generation frequency synthesizer and (2) the pulse programmer is based on a high-speed 32-bit parallel interface card in a desktop computer. The spectrometer is well suited for single-frequency channel experiments such as nuclear quadrupole resonance and deuterium quadrupole echo NMR experiments. Because the rf phase shifting is done digitally, the spectrometer operates easily over a wide frequency range, here 10–300 MHz. The pulse programmer and other software functions are written in LabView, a graphical programming language.