Study of the Ionization in a Field Ion Microscope Using Pulsed-Laser

Abstract

Field ion microscope (FIM) is an instrument used to analyze the structure of specimen surface at an atomic scale. In recent years, a position-sensitive detector (PSD) has been used as a detector in FIM. By using the PSD, much information can be obtained, such as the number of released ion from each position. In this work, we studied the ionization in FIM measurement using pulsed laser. In the FIM measurement using the pulsed laser, ions with specific time structure relative to the laser pulse were detected, and the FIM image of these ions was similar to that of a normal FIM image, although the spatial resolution decreased. Furthermore, we observed delay in ionization at the parallel axis along the irradiation direction of the pulsed laser, and we believed that this was caused by the delay in the ionization due to the heat transfer. From the experimental results, we proposed that the heat caused by the pulsed laser was involved in the ionization, in contrast to conventional field ionization. [DOI: 10.1380/ejssnt.2018.190]