Measurements of the charge-changing cross sections ${\sigma }_{g-}$ and ${\sigma }_{g+}$ are reported for 1-25-keV fast $\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}$ atoms incident on a Na-vapor target. The cross section ${\sigma }_{g-}$ falls from 3′${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at 1 keV to 3.5′${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$ at 25 keV. The cross section ${\sigma }_{g+}$ rises from 1.1′${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ at 2 keV to 1.5′${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^{245}$ at 25 keV. Measured values of the equilibrium fractions $F_{-}^{\infty }$ and $F_{+}^{\infty }$ for incident ${\mathrm{H}}^{-}$ ions are also presented.

• Received 13 September 1983

DOI:https://doi.org/10.1103/PhysRevA.29.1083