(a) 2D 3QMAS spectra of meridional Alq
( α -phase). The optimized excitation pulse and conversion pulse lengths were 3.8 μs and 1.8 μs. A total of 64 t1 increments was taken with 10 μs of dwell time with 288 transients per increment. The recycling delay was 1 s. Total experiment time was 5 hours. (b) The anisotropic slice along the direction parallel to the F2 dimension. (c) The isotropic projection along the F1 dimension.