Method for reducing homonuclear broadening in magnetic resonance spectra of solids
AssigneeInternational Business Machines Corporation
InventorsDonald C. Hofer, Raymond D. Kendrick, Costantino S. Yannoni
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Abstract
A method for line narrowing in nuclear magnetic resonance (NMR) studies in solids is described. The method employs quasi-continuous amplitude modulation of an rf field wherein the field is eliminated at intervals for short periods of time at or about the time when the amplitude for both the maximum and minimum approach zero, these intervals creating windows where the NMR signal can be observed.
Claims6
In a method of operation of a magnetic resonance spectrometer employing a Zeeman field and at least one orthogonal radio frequency (rf) field for energization of the material, the improvement comprising:
- varying the Zeeman field to produce a sinusoidal off-resonance component of the Zeeman field of amplitude ##EQU10## and of frequency .omega..sub.a ;
- where .omega..sub.a is a constant which is large with respect to the width of an NMR line of the material and .beta. is a constant;
- applying a first rf field normal to said off-resonance component of the Zeeman field and modulating the amplitude of said rf field to produce a sinusoidal envelope of amplitude ##EQU11## and of frequency .omega..sub.a ;
- selecting .beta. such that J.sub.0 (2.beta.)=-2J.sub.0 (.beta.).perspectiveto.0;
- by eliminating said first rf field for about 2 to 5 microseconds at or about the zero crossing of said sinusoidal envelope once per audio cycle to introduce discontinuities therein;
- and
- employing said discontinuities for observation windows for the NMR signals.
A method of operation of a magnetic resonance spectrometer comprising:
- amplitude modulating an envelope of a first rf field and adjusting the amplitude of said envelope of said modulation to produce a sinusoidal envelope of amplitude ##EQU14## and of frequency .omega..sub.a ;
- amplitude modulating an envelope of a second rf field which is normal to said first rf field direction and adjusting said modulation to produce a sinusoidal envelope of amplitude ##EQU15## and of frequency .omega..sub.a ;
- selecting .beta. such that J.sub.1 (2.beta.)=-1/6;
- applying said first rf field and said second rf field for alternating periods of times each of said periods of time being 1/.omega..sub.a long;
- eliminating said first rf field and said second rf field every second audio cycle for about 2 to 5 microseconds at or about the zero crossing of these sinusoidal envelopes to introduce discontinuities into said rf fields;
- and
- employing said discontinuities for observation windows for the NMR signals.
Dependencies are inferred from the claim text.