Extraordinarily slow nuclear spin relaxation in frozen laser-polarizedXe129

We studied the very slow nuclear spin-lattice relaxation of solid ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ as a function of temperature and magnetic field using laser-polarized nuclei. Relaxation times in excess of 500 h were measured. We present evidence for a new relaxation mechanism which results from a Raman spin-phonon scattering process involving the spin-rotation interaction. We also establish the existence of cross relaxation between ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ and the other magnetic isotope ${}_{}{}^{131}{}_{}{}^{}\mathrm{Xe}$ and demonstrate that laser-polarized ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ can be used to cross polarize other nuclei that are present in the lattice.