We report the first measurement of the spin-exchange rate coefficient for binary collisions between Cs and ${}^{129}\mathrm{Xe}$ atoms in the temperature range $110<T<150°\mathrm{C}$ at a $9.4\text{−}\mathrm{T}$ magnetic field. Under these conditions, binary spin-exchange collisions dominate the longitudinal nuclear spin-relaxation rate $1∕T_1$ of ${}^{129}\mathrm{Xe}$ gas. We measured $1∕T_1$ of a thermally polarized Xe gas using the saturation-recovery of conventional nuclear magnetic resonance. We also directly measured the Cs atomic number density [Cs] by using Faraday rotation of the linear polarization of a probing laser beam passing through the sample. The measured rate coefficient is $\kappa \left(9.4\mathrm{T}\right)=d(1∕T_1)∕d\left[\mathrm{Cs}\right]=(2.81\pm 0.2)\times {10}^{-16}{\mathrm{cm}}^3∕\mathrm{s}$, which is about a factor of 1.6 higher than the previously measured spin-exchange rate coefficient of ${}^{129}\mathrm{Xe}\text{−}\mathrm{Rb}$ binary collisions. Using a calculated magnetic decoupling factor, we extrapolate our result to zero magnetic field: $\kappa \left(0\mathrm{T}\right)=(4.1\pm 0.3)\times {10}^{-16}{\mathrm{cm}}^3∕\mathrm{s}$.

• Received 25 February 2004

DOI:https://doi.org/10.1103/PhysRevA.69.061401