ISS, SIMS (recoil target ions), and ion‐produced photon emission (IPP) from surfaces subject to low‐energy ion bombardment have been compared by simultaneous measurement of the effect of reactive gas adsorption on each signal. A direct correlation between the three signal strengths has been established. Cross sections for desorption of CO from Ni due to low‐energy ion bombardment have been measured independently and simultaneously by two of the three methods.