Time-dependent intensity corrections for accurate quantitative point or X-ray mapping analysis by electron microprobe

Many materials undergo modifications to both structure and chemistry during electron bombardment in an electron probe microanalyzer (EPMA). This results in changes to the emitted X-ray intensities by various physical processes including heating, breaking of molecular bonds, ionization, volatilization and sputtering, subsurface static charging and subsequent mobility of the measured elements. Most of these processes are proportional to the degree and duration of electron beam exposure (analytical time, acceleration voltage, beam current, and beam focus) and to the thermal and electrical conductivity of the analyzed material. Therefore, quantitative accuracy is dependent upon correction schemes that monitor changes in X-ray emission over time, a process called Time Dependent Intensity (TDI) corrections. This paper investigates various applications of TDI corrections and demonstrates that accurate point analyses can be obtained with such corrections. Moreover, the combination of replicate X-ray mapping with a TDI correction can produce precise and accurate quantitative element maps for beam-sensitive materials, expanding the range of materials and analytical conditions suitable for EPMA applications.