th  - 1987 - 51st ENC Conference

MFI9
AN EFFICIENT STATOR/ROTOR ASSEMBLY
FOR MAGIC ANGLE SPINNING I~R
by
Yt Jtn Jtang .1, Warner R. Woolfenden 1, Donald W. Alderman 1,
Charles L. Rayne 1, Rona]d J. Pugmire 2, and David M. Grant 1
(1) Department of Chemistry
(2) Department of Fuels Engineering
University of Utah
Salt Lake City, Utah ~I12
ABSTRACT
A newlydesigned stator assembly for cylindrical spinners used in
magic angle spinning nuclear magnetic resonance experiments is
described. Separate driving and bearing gas chambers allow variable
and stable spinning speeds and thts design permits easy starting and
stopping of the rotor. Isolation of the chambers is achieved with the
application of pressure screws rather than o-rings or glue lines to
avoid leakage at htgh gas pressures. The overall dimensions are opti-
mal to facilitate easy assembly. Some significant modifications have
been made to an earlter spinner design. These improvements gtve
better efficiency and concentricity of the spinner. Applications are
illustrated with carbon-13 CP/MAS spectra carried out at different
rotor spinning rates.