th - 1987 - 51st ENC Conference
th - 1987 - 51st ENC Conference
th - 1987 - 51st ENC Conference
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WF20<br />
DESIGN OF AN EFFICIENT PROBE FOR HIGH FIELD<br />
MULTINUCLEAR CP/MAS NMR OF SOLIDS<br />
Preben Daugaard, Vagn Langer, and Hans O. Oakobsen*<br />
Department of Chemistry, University of Aarhus,<br />
DK-8000 Arhus C, Denmark<br />
Very high-speed, stable spinning is a desirable technique in multi-<br />
nuclear CP/MAS, MA5, or VAS (variable angle spinning) experiments of solid<br />
materials for several reasons. For example <strong>th</strong>is applies to bo<strong>th</strong> high-field<br />
CP/MAS studies of spin-l/2 (e.g. 13C, ]SN, 31p, and ]]3Cd) and quadrupolar<br />
nuclei (e.g. liB, 2~Na, and 27AI).<br />
We describe <strong>th</strong>e design of a high speed multinuclear CP/MAS probe for<br />
<strong>th</strong>e 51 mm bore superconducting magnet of our Varian XL-300 spectrometer.<br />
The spinning speed of <strong>th</strong>e 7 mm o.d. rotors can routinely and accurately be<br />
set at any value up to at least 10 kHz wi<strong>th</strong> a stability of a few hertz.<br />
Air drive pressures of I and 4 bar are required for 4.5 and 9.0 kHz spin-<br />
ning, respectively, lhe spinner assembly employs a separate double air<br />
bearing which acquires an air pressure of only i-2 bar for a11 spinning<br />
speeds up to 10 kHz. We also expect to be able to discuss preliminary re-<br />
sults for <strong>th</strong>e design of a 15 kHz spinner assembly during <strong>th</strong>e meeting.<br />
The simplicity of <strong>th</strong>e splnner assembly, and <strong>th</strong>e high sensitivity and<br />
high electronic efficiency of <strong>th</strong>e probe wili be demonstrated along wi<strong>th</strong><br />
"real life" applications.<br />
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