Scanning Atom Probe Analysis Alternately Triggered by Voltage and Laser Pulse

Abstract

Voltage pulse which has been used from the establishment of atom probe (AP) in the 1960's is going to be replaced by short pulsed laser with high repetition rate in the nanometer scale characterization of materials by 3D-AP. Scanning Atom Probe (SAP) has a miniature electrode for acceptance of non-needle shaped specimens which allows us to analyze non-solid materials which are common in chemistry. The selectivity and the adaptability of voltage pulse and laser pulse are not clear in the non-bulk materials which are common in chemistry but not familiar in AP field. Two types of trigger, voltage pulse and laser pulse, were applied alternately to the identical sample to perform direct comparison. Tungsten tip, conventional material in AP, and amino acid (L-Tryptophan) supported on carbon nanotube were chosen as candidates for this analysis. The dual trigger system successfully worked on metallic sample and the selectivity of the ion species and adaptability were demonstrated on molecular system.

Alternate field evaporation by changing laser pulsing and voltage pulsing dynamically for atom probe analysis

“…The criterion for choosing appropriate trigger method is not clear and under discussion because it is difficult to compare the result of 2 triggering methods applied on the same sample in atomic scale . The precise comparison of 2 triggering methods was proposed by the authors by applying voltage pulse and laser pulse alternately to the identical sample . The results of mass spectrometric composition and spatial information of desorbed ions reflected the mechanism of triggering field evaporation.…”

“…[3][4][5] The precise comparison of 2 triggering methods was proposed by the authors by applying voltage pulse and laser pulse alternately to the identical sample. 6 The results of mass spectrometric composition and spatial information of desorbed ions reflected the mechanism of triggering field evaporation. But the evaporation order was almost random or disordered showing no or little correlation between 2 triggering methods applied alternately during analysis.…”