Effects of finite rf pulses and sample spinning speed in multiple-quantum magic-angle spinning (MQ-MAS) and multiple-quantum quadrupolar Carr-Purcell-Meiboom-Gill magic-angle spinning (MQ-QCPMG-MAS) nuclear magnetic resonance of half-integer quadrupolar nuclei

The multiple-quantum magic-angle spinning (MQ-MAS) solid-state nuclear magn etic resonance (NMR) experiment and a sensitivity-enhanced variant detectin g the second-order quadrupolar powder pattern through a train of quadrupola r Carr-Purcell-Meiboom-Gill refocusing pulses (MQ-QCPMG-MAS) are analyzed w ith respect to the effects of finite radio frequency (rf) pulse irradiation and the MAS frequency. Taking these effects explicitly into account, it is possible to accurately determine optimum conditions for excitation of MQ c oherences and reconversion of these into detectable single-quantum coherenc es as well as simulate the second-order quadrupolar lineshape necessary to extract accurate parameters for quadrupolar coupling interactions and isotr opic chemical shifts. This accurate determination is of great importance fo r the exploitation of MQ-MAS and MQ-QCPMG-MAS NMR experiments for quantitat ive determination of site populations. The various effects are described an alytically and demonstrated by numerical simulations and by Rb-87 MQ-MAS an d MQ-QCPMG-MAS experiments on RbNO3.