Calibration of the Atom Probe FIM

摘要: Accurate identification of atomic species in the atom probe FIM requires a highly shielded tip assembly, as well revision equation formerly used to compute m/n ratios. Voltage reflections on unterminated pulse transmission line cause actual evaporation at be greater than applied by ``pulse factor'' α. In addition, recorded flight time ion under investigation differs from constant electronic delay δ. Using either two single isotope calibration techniques, both α and δ can determined. For assembly technique gives value α=2.00±0.05 δ=0.06±0.02 μsec. Typical absolute mass determination using these values is within ±0.6 amu m/n=20, ±1.6 m/n=100. When masses near known species, like hydrogen‐ or helium‐metal molecular ions, are detected, practical resolution reaches ±0.2 middle range.