Radiation Damping

¹H inversion recovery experiment:
the strong center peak corresponds to protons not coupled to any NMR active nuclei, flanked by ^115,117,119Sn satellites with a coupling constant of approximately 54 Hz, and the small ¹³C satellites with a coupling constant of 128 Hz.
The only unusual thing is the broadening observed for the strong center peak (15.5 Hz fwhh), compared to the 13C satellites(< 1 Hz), as well as a strange phase shift.

The analysis of the inversion recovery experiment reveals another very unusual observation:
the apparent spin-lattice relaxation time of the protons associated with the center peak, 0.08 sec, is two orders of magnitude shorter than that of the satellites, ca. 8 sec.

pulse length calibration:
this well-known experiment for the calibration of flip angles illustrates the effect of radiation damping rather nicely:
while the peaks due to the satellites follow the typical sinusoidal pattern as a function of pulse duration, the center peak exhibits a different behavior: starting at an flip angle of about 90 deg, there is a phase twist that gets increasingly stronger and reaches a maximum at 180 deg. Only at 360 deg basically no residual signal is left.