Analysis of the performance of NQR composite pulses

Abstract

This paper presents an analysis of the performance of composite pulses in the pure NQR spectroscopy of spin-3/2 nuclei. Computer simulations are given of the offset compensation efficiency of such pulses as applied to single crystals as well as powders. A set of Pauli operators that are linear combinations of single-transition operators has been used for the spin-dynamics calculations. Experimental investigations of the ³⁵Cl and ³⁷Cl NQR of mercuric chloride powder and ³⁵Cl NQR of pentachlorophenol powder are reported as a function of resonance offset. These results suggest that the 45̅° 135 ° sequence is an efficient composite π/2 pulse, while 90°_0° 270°_90° 90°_0° and 315°225̅° 90° are efficient composite π pulses; these effectively compensate for offset/EFG inhomogeneity effects and are not critical to setup, being tolerant to flip-angle errors.