Electron capture by slowFeq+ions from hydrogen atoms and molecules

Total electron-capture cross sections have been measured for collisions of ${\mathrm{Fe}}^{q+}$ ions ($3\le q\le 14$) with H and ${\mathrm{H}}_2$ at energies in the 10-95 eV/amu range. The cross sections increase approximately linearly with increasing ionic charge $q$, and, for atomic hydrogen, can be represented by the empirical formula: $\sigma =q\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ with an rms deviation of ±26%. For ${\mathrm{Fe}}^{5+}$ and ${\mathrm{Fe}}^{6+}$, for which higher-energy data exist, the cross sections are found to be essentially energy independent over the range $17<E<\mathrm{}2000\mathrm{}$ eV/amu. The cross sections for an atomic H target average 26% larger than for ${\mathrm{H}}_2$. Agreement with generalized theoretical models is within a factor of 2 or better.