X-ray emission cross sections for carbon bombarded with 4- to 40-MeV C, N, and O ions

Cross sections for production of target-atom carbon $K$ x rays in thin evaporated carbon films are determined from spectra obtained using a double-focusing soft-x-ray spectrometer with calibrated transmission. A maximum value of 2.3 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}19}$ ${\mathrm{cm}}^{2}$ is found for 18-MeV oxygen ions. A maximum ionization cross section of 4.8 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$ is estimated from the data. Cross sections for x rays on both sides of the carbon $K$ edge are determined. Nitrogen ions produce more $L$-shell ionization at low energies than carbon or oxygen ions, both of which create very few $K{L}^{2}$ satellite x rays below about 9 MeV.