Constant-time period without J evolution

In this case, a typical example is described when I, X, and Y are heteronuclei and there is no coupling evolution during t₁.

   

Evolution of X chemical shift: (t₁/2)+d5-(d5-t₁/2)=t₁
Evolution of J_IX and J_XY coupling constant: (t₁/2)-d5+(d5-t₁/2)=0
Evolution of J_XX' coupling constant: (t₁/2)+d5+(d5-t₁/2)=2*d5

Example 1: Constant-time ¹³CA period in a out-and-back 3D HNCA pulse scheme, in which there is no coupling evolution for J_CAH, J_NCA and J_CACO.
 

 

Example 2: The mirror scheme can be also designed, as demonstrated in a 3D HNCA experiment for deuterated proteins.

 

Easy implementation on AVANCE spectrometers.