Indirect Spin Saturation. III. Solutions of Spin-Density Matrix

For homonuclear spin one‐half ${\mathrm{AB}}_n\mathrm{\hspace{0.17em}+\hspace{0.17em}C}$ systems, in which $A$ and $C$ are in chemical exchange, the effect of a strong irradiation at $C$ on the intensity of the ${\mathrm{AB}}_n$ group is studied. Alexander's treatment on spin‐density matrix is applied to the double‐resonance systems. The matrix equations are solved. The results are compared with experimental data for an ${\mathrm{AB}}_2\mathrm{\hspace{0.17em}+\hspace{0.17em}C}$ system. A new quantity $T_3$ which is dependent upon ${\mathrm{J,\; \delta ,\; T}}_2$ , and ${\tau }_3$ , is introduced to characterize the spin exchange due to spin–spin interaction.