1 Scope
This document specifies a method for determining the maximum count rate for an acceptable
limit of divergence from linearity of the intensity scale in single ion counting time-of-flight
(TOF) secondary ion mass spectrometers using a test based on isotopic ratios in spectra
from poly(tetrafluoroethylene) ( PTFE ). It also includes a method to correct for intensity nonlinearity arising from intensity
lost from a microchannel plate ( MCP ) or scintillator and photomultiplier followed by a time-to-digital converter ( TDC ) detection system caused by secondary ions arriving during its dead-time. The correction
can increase the intensity range for 95 % linearity by a factor of up to more than
50 so that a higher maximum count rate can be employed for those spectrometers for
which the relevant correction formulae have been shown to be valid.