Radio-frequency-mediated dipolar recoupling among half-integer quadrupolar spins

It is demonstrated that through-space recoupling can be achieved in dipolar coupled quadrupolar spins in the presence of an appropriate radio-frequency field. Experimental and theoretical results for Na-23-Na-23 pairs are presented that elucidate the experimental conditions leading to homonuclear dipolar transfer. The effect of adiabatic amplitude modulation on spin-3/2 systems is compared to spin-1/2 cases and applications of this approach in the context of high resolution multiquantum magic angle spinning for dipolar filtering and correlation are discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)01810-9].