Contents

06 October 1989
Vol 246, Issue 4926

About The Cover

Motions involved in double rotation, a means to obtain sharp nuclear magnetic resonance (NMR) spectra for quadrupolar nuclei in solid materials. The sample is contained in the inner (orange) cylinder, which rotates ·7000 times per second around an axis inclined at 30.6° to the axis of the outer (blue) cylinder. The outer cylinder, which has a diameter of ·1 centimeter, rotates ·1000 times per second around an axis inclined at 54.7° to the magnetic field. See page 71. [Computer-generated image courtesy of Lawrence Berkeley Laboratory]