Particle-induced x-ray emission in stainless steel using 30keV Ga+ focused ion beams

Characteristic x-ray emission from a well grounded stainless steel specimen using standard 30keV Ga+ focused ion beam instrumentation is demonstrated. X-ray yields are found to be on the order of 10−10 per incident ion, consistent with previous studies of low energy, high mass ion-solid interactions. X-ray yields were found to be highest for low energy transitions or low atomic number target atoms. Bremsstrahlung x-ray emission was found to be minimal, possibly increasing detectability compared with electron beam induced x-rays. Yields were also estimated to be on the order of 10−11 per sputtered atom, or approximately one x-ray per sputtered monolayer. While velocity coupling between the primary ion beam and target atom electrons is not possible under these experimental conditions, it is argued that x-ray emission is, in fact, due to recoil effects of the ion-solid interaction.