Fig. 3: Schematic explaining disappearance of isoleucine and leucine peaks when the constant-time duration is set to T = 3/(2 ¹J_CC).

The simulation shows the transverse projection of the ¹³CH₃ Leu (red), Val (blue) magnetization vector, with arrows showing the sense of rotation with respect to the intrinsic chemical shift frequency. The resulting ¹³CH₃-x magnetization for Leu (red), Val (blue, dashed) are shown below. The constant-time evolution period T is set to 42 ms (3/(2 ¹J_CC)). The shaped pulse at the T/2 selectively decouples C^γ_Val from C^β_Val, resulting in the appearance of the valine peaks. The disappearance of isoleucine and leucine peaks in the spectrum is due to the cancelling out of the anti-phase term arising because of the ¹³C–¹³C spin coupling.