HSQC

From NMR Wiki

HSQC - Heteronuclear Single Quantum Coherence.

Term HSQC is also frequently used to describe 2D NMR experiment correlating chemical shifts of nuclei of two different atoms (one type of atom in dimension ω1 and another type of atom in ω2). Cross peaks will be observed for pairs heteroatoms that have scalar coupling in range selected by the HSQC experiment - usually corresponding to coupling between directly connected atoms.