F19nuclear relaxation at the interface between liquidHe3and a solid substrate at high field and low temperature

Using NMR techniques, we have measured the rate at which ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ magnetization is relaxed at the surface of a fluorocarbon solid through contact to liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. These measurements at millikelvin temperatures show that the relaxation rate continues to follow a power-law dependence over a broad range of ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ Larmor frequencies $f (10\mathrm{}-136 \mathrm{MHz}): \frac{1}{T_{1S}}\propto \frac{1}{f^{1.2}}$. These results complement recent measurements by Maegawa et al. of the high-frequency ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ relaxation rate which is approximately proportional to $f^{-1\mathrm{}}$.