Analysis of the relative angular response of the degenerate four-wave mixing signal in alkali-metal atoms mixed with a buffer gas allows direct determination of the excited-state diffusion coefficients. The measured diffusion coefficients D at 96 °C and 760 torr for the cesium 6${\mathit{P}}_{1/2}$ and 6${\mathit{P}}_{3/2}$ state atoms in neon gas are 0.348(4) ${\mathrm{cm}}^2$ ${\mathrm{s}}^{\mathrm{-}1}$ and 0.281(8) ${\mathrm{cm}}^2$ ${\mathrm{s}}^{\mathrm{-}1}$, respectively. © 1996 The American Physical Society.

• Received 5 July 1995

DOI:https://doi.org/10.1103/PhysRevA.54.3335