Fig. 1. A robust and versatile singlet NMR sequence.

The gc-M2S pulse sequence for converting longitudinal magnetization into singlet spin order and back to magnetization in a homonuclear 2 spin-½ system is shown. Full and empty rectangles represent π/2 and π hard pulses, respectively, and the semicircles represent gradients. The sequence consists of a magnetization-to-singlet block, a T₀₀ block to project into the singlet state, a singlet-to-magnetization block, a z-purge block, and a (π/2)_ϕ5 observe block. The phases ϕ₁ and ϕ₄ are collinear. The phases ϕ₂ and ϕ₃ are collinear but in quadrature to ϕ₁ and ϕ₄. The relevant product operators of each step are given on the right. The detailed discussion can be found in the Supplementary Materials.