The Effect of ¹H RF Irradiation on ¹³C Spin-Lattice Relaxation

The extended Solomon equations are used to describe the ¹³C spin-lattice relaxation with the ¹H RF field irradiation.It is shown that the ¹³C spin-lattice rclaxation under the ¹H RFirradiahon is generally a triple-exponential course, but can be reduced to single-exponential in the absence of the ¹H initial magnetizations and with strong enough RF field irradiation. Based on the numerical calculation, the large difference between the spin-lattice relaxation curves obeying T₁^c<T₁^H and those obeying T₁^c>T₁^H is indicated. The methyl ¹³C resonances in L-Valine in the solid state are examined, whose experimental results agree well with the theoretical ones