The influence of experimental parameters and specimen geometry on the mass spectra of copper during pulsed-laser atom-probe tomography.

We have studied the influence of experimental factors and specimen geometry on the quality of the mass spectra in copper (Cu) during pulsed-laser atom-probe tomography. We have evaluated the effects of laser pulse energy, laser pulse frequency, specimen base temperature, specimen tip radius, and specimen tip shank half-angle on the effects of mass resolving power, (m/Δm), at full-width at half-maximum and at full-width at tenth-maximum, the tail size after the major mass-to-charge state (m/n) ratio peaks, and the mass spectra. Our results indicate that mass resolving power improves with decreasing pulse energy between 40 and 80 pJ and decreasing base temperature between 20 and 80 K. The mass resolving power also improves with increasing tip radius and shank half-angle. A pulse frequency of 250 kHz slightly improves the mass resolving power relative to 100 or 500 kHz. The tail size decreases with increasing pulse energy. The mass resolving power improves when the cooling time is reduced, which is influenced by the thermal diffusivity of Cu and the specimen base temperature.