Laser-Assisted Field Evaporation of Chromia with Deep Ultraviolet Laser Light.

In this work, samples of chromia (Cr2O3) scale have been prepared for atom probe tomography and field evaporated with deep ultraviolet laser light (258 nm wavelength). The investigated range of laser energies spans more than three orders of magnitude between 0.03 and 90 pJ. Furthermore, the effects of detection rate and temperature were investigated. Simultaneous voltage and laser pulses were employed on additional needle specimens to reduce the standing voltage and minimize background noise during the measurement. Smooth evaporation with minimal mass spectrum peak tails was maintained over the whole range of measurement parameters. High laser energies result in significant underestimation of the oxygen content. Only laser energies below 1 pJ resulted in measured values near the expected oxygen content of 60 at%, the closest being about 58 at%.