In an experiment to estimate T1 using the inversion-recovery sequence, three peaks in the spectrum were observed to go through a null at 0.5, 0.6 and 0.8 s, respectively. Explain how an estimate for T1 can be obtained from such measurements, and give the value of T1 for each line. A solvent resonance was still inverted after a delay of 1.5 s; what does this tell you about the relaxation time of the solvent?