β Scribed by Amir Goldbourt; Shimon Vega
No coin nor oath required. For personal study only.
5QMAS experiments on spin-5/2 systems display a low sensitivity compared with their 3QMAS counterparts. Nevertheless, the superior resolution of 5QMAS over 3QMAS makes these experiments a favorable choice for many materials. We report an enhancement scheme for the 5QMAS experiment, using an improved five-quantum excitation pulse scheme combined with a FAM-II conversion pulse. The results are verified experimentally on a polycrystalline sample of Ξ³-27 Al 2 O 3 , showing an enhancement factor of 2.4 over the simple two-pulse (CW) 5QMAS scheme. Numerical computations of the efficiency parameter support these results.
π SIMILAR VOLUMES
Three population transfer techniques for improving the sensitivity of the central transition of NMR spectra from half-integer quadrupolar nuclei in the solid state are described. Two of the methods attempt to invert the populations of energy levels associated with the satellite transitions either by