DEUTERIUM DOUBLE-QUANTUM NMR WlH MAGIC ANGLE SPINNING

It was recently demonstrated that lugh-resolution deutenum NMR m sohds may be accomphshed by magc angle sample spuming e\ren when the rotation frequency, wJ277 = 1 kHz, IS much less than the quadrupole coupling, WQ/21r = 4 %7-qQ/h = 130 l&I2 [l-4] The sample rotation removes the broademng of spectra of amorphous and polycrystalline samples due to the anlsotropic quadrupole and chemical-shift interactions. Isotropic chemical-shft spectra can be obtained by sampling the free induction decay (FID) synchronously wth the sample rotation [5] _ This results m a narrowmg of the deutenum powder spectra by a factor of l/2 (3cos% I), where 8 IS the angle between the spinner axis and the direction of laboratory magnetic field, B. Practically, thus yields a narrowing of about three orders of magmtude. Thus an extremely stable sample spinner is required, which is described elsewhere [4]. having angular fluctuations smaller than a few mdhdegrees However, it was recently shown that by detectmg the deuterlum doublequantum transitions the anisotroplc chcmicalsluft spectra can be obtamed smce the double-quantum absorption hnes are free of large first-order quadrupolar broadening [6-101 A novel posslb&ty, wluch we demonstrate here, 1s to combine magc angle spinning with double-quantum NMR in an altematlve approach to high resolution m solids. In removmg the quadrupole coupling via the detection of double-quantum transitions the spinner requuements become much less stnngent smce It has only to remove the smaller chemlcal-