Enhancing MQMAS of low-γ nuclei by using a high B1 field balanced probe circuit

A balanced probe circuit is used to generate high B1 magnetic field for sensitivity enhancement of multiple-quantum magic-angle spinning (MQMAS) experiment applied to low-γ quadrupolar nuclei. Electrical balancing of the sample coil can cut the peak voltage by a half, therefore improving the power handling when generating a two-fold higher B1 field. Experimental results, illustrated here with 25Mg data for two layered double hydroxides, show that the MQMAS efficiency increases more than linearly with the B1 field strength. The multiplicative enhancements from high B0 and B1 fields and an optimized MQMAS pulse sequence provide the critically needed sensitivity for acquiring MQMAS spectra of low-γ quadrupolar nuclei such as 25Mg at natural abundance.