QMGreensite_merged

The second line shows that the S^3 CT sequence selectively inverts the
component ofSzmagnetization that is coupled to anIspin in the state.
A pictorial representation of the effect of the S^3 CT sequence on
coherences is illustrated using zero-quantum and double-quantum
coherences as an example in Fig. 2.7. The selective inversion is seen to
transferI–Sþcoherence intoI–S^ coherence andI
S
coherence into
I
S^ coherence. An explicit calculation yields

I
Sþ )

I^ Sy


I
S^ ,

I
S
 )

I^ Sy

I
S^ ,

½ 2 : 296 Š

which is necessary to obtain the correct signs of the operators.
For completeness, the corresponding selective inversion across the

I – S a

I–S+

a

aa

ab

ba

bb

I–S–

b

aa

ab

ba

bb

pIaSy

pIaSy

I–Sb

FIGURE 2.7 Energy level diagram for S^3 CT pulse sequence. The S^3 CT
pulse sequence element is equivalent to a selective inversion across the
ji $
transition, as indicated by the curved arrows. (a) The S^3 CT
sequence converts zero-quantum coherence to single-quantum coherenceI
S^.
(b) The S^3 CT sequence converts double-quantum coherence to single-quantum
coherenceI–S^.

2.7 PRODUCTOPERATORFORMALISM 101