Variable-angle double rotation technique: a new two-dimensional high-resolution technique for quadrupolar nuclei

Abstract

We describe a new two-dimensional high-resolution technique for nuclei with semi-integer spins subjected to strong quadrupole interactions. This variable-angle double rotation (VADOR) technique separates anisotropic spectral patterns according to the isotropic shift of each species. No sudden sample reorientation is needed for VADOR which can consequently be used regardless of the “relaxation times”. This technique can also be utilized to characterize slow molecular reorientations in two- or three-dimensional experiments. We also propose a new geometry for DOR probes ( θ e = 70.124 °, θ i = 54.736 °) which suppresses first-order interactions (chemical shift anisotropy and dipolar) more efficiently than the geometry ( θ e = 54.736 °, θ i = 30.556 °) presently employed.