Characterisation of secondary electron multiplier nonlinearity using MC-ICPMS

Additional tests show that after a high intensity beam was measured on the SEM of the MC-ICPMS system, the SEM yield is elevated for at least 15-20 s, which can be envisaged as a memory effect related to the intensity of previously measured signals. Therefore, it is impossible to see the nonlinearity effect at low count rates using a peak jumping routine on the ICPMS because of intervening high intensity beams (e.g., 235U and 238U) applied to the SEM. This “memory” effect has important implications for MC-ICPMS measurement protocols that use multi-static or peak jump routines.