title: Automatic NMR field-frequency lock-pulsed phase locked loop approach.
abstract: A self-contained deuterium frequency-field lock scheme for a high-resolution NMR spectrometer is described. It is based on phase locked loop techniques in which the free induction decay signal behaves as a voltage-controlled oscillator. By pulsing the spins at an offset frequency of a few hundred hertz and using a digital phase-frequency discriminator this method not only eliminates the usual phase, rf power, offset adjustments needed in conventional lock systems but also possesses the automatic pull-in characteristics that dispense with the use of field sweeps to locate the NMR line prior to closure of the lock loop.
authors.affiliation: Institut d'Electronique Fondamentale, Laboratoire associe au CNRS, Universite Paris-Sud, 91405 Orsay, FranceLaboratoire de Chimie Organique Structurale, Universite Paris Sud, 91405 Orsay, France.
authors.forename: S
authors.initials: S
authors.lastname: Kan
authors.forename: P
authors.initials: P
authors.lastname: Gonord
authors.forename: M
authors.initials: M
authors.lastname: Fan
authors.forename: M
authors.initials: M
authors.lastname: Sauzade
authors.forename: J
authors.initials: J
authors.lastname: Courtieu