Some quadrupolar effects onT1(H)for nuclear spins

We calculate effects on $T_1\mathrm{}\left(H\right)\mathrm{}$ for nuclear spins due to several distinct interactions that depend on the quadrupole moment of the nuclear spins. We find, for example, that in metals the ratio $\frac{T_1(H\to \infty )}{T_1\mathrm{}\left(0\right)\mathrm{}}$ can be greater than 2 because of quadrupolar spin-spin interactions even in the absence of electric field gradients. We also show that $T_1\mathrm{}\left(H\right)\mathrm{}$ can depend on the spin $I$ of a nucleus if $T_1$ is dominated by certain dynamic quadrupolar mechanisms.