For binary and ternary alloys of Fe, Ni, and Cr covered with oxygen and for solid oxides of these elements, the emission yield of monoatomic ions, Fe+, Ni+, and Cr+, are linear functions of the atomic concentrationsCFe,CNi, andCCr. This empirical law suggest that the emission ofM+ions obeys a binary process, involving dynamic electronic exchanges between theMsputtered atoms and their neighbors during inelastic collisions. The determined formula for the interrelationship between theM+intensities and the atomic concentrations is applied to the quantitative analysis of oxide films developed at high temperature on a refractory alloy.