Consider the three-spin system opposite which consists of a proton I coupled to a 13C, S1, with coupling constant j1S1; S1 is further coupled to a second l3C, S2, with coupling constant JS1,S2- Note that there is no coupling between I and S2.
For the constant time HSQC pulse sequence shown in Fig. 10.26 on page 357, and starting with equilibrium magnetization in the / spin, work out the 5-spin operators present at the end of the constant time period; assume that τ1 = 1 /(4J1S1,) and τ2 = 1 /(4J1S1).
Determine which of these operators become observable on the J spin at the end of the sequence, and hence predict the form of the spectrum. How do the peaks vary in intensity as a function of the constant time T? What is the optimum value for this time?