Heisenberg picture approach to polarization transfer by the DEPT sequence

The simple Heisenberg vector model, though useful for numerous nmr pulse sequences, was found inadequate to describe the DEPT sequence, which was subsequently analyzed by an unwieldy Schroedinger picture approach. Because this latter approach is not amenable to treating either deviations from, or applications of, the ideal DEPT sequence which arise in practical cases, a Heisenberg picture analysis is presented which is more mathematically formal than the simple vector model. In terms of efficiency, flexibility, and generality this represents a vast improvement on the previous Schroedinger picture approach which was restricted to treating CH, CH2, and CH3 groups individually for specific initial conditions. The new approach is applicable to a general ISn group, where the spin of I is one-half but that of S is arbitrary, for a variety of initial conditions. More importantly it is efficient enough to form the basis of analyses of the more complicated DEPT-type sequences which will be used for practical applications.