Signal enhancement in 5QMAS spectra of spin-5/2 quadrupolar nuclei.
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 gamma-(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 epsilon support these results.
Goldbourt
Amir
A
Weizmann Institute of Science, Rehovot, 76100, Israel. amir.goldbourt@weizmann.ac.il
Vega
Shimon
S