Observation of Nuclear Spin Waves in Spin-Polarized Atomic Hydrogen Gas

Abstract

We have observed narrow, distinct resonances in the NMR spectrum of dilute spinpolarized atomic hydrogen gas ($n\ensuremath{\sim}{10}^{16}$ atoms/${\mathrm{cm}}^{3}$). The dependence of the observed spectra on temperature, density, polarization, and magnetic field gradient is consistent with theoretical predictions for spin-wave excitations damped by diffusion. We have measured the parameter $\ensuremath{\mu}$, which is a measure of the importance of exchange effects in spin-transport processes, and the diffusion coefficient ${D}_{0}$, both of which are in reasonable agreement with theory.