Antenna effect in laser assisted atom probe tomography: How the field emitter aspect ratio can enhance atomic scale imaging

Abstract

In this Letter, we show that, in contrast to what is generally admitted in laser assisted atom probe, it is possible to probe a tip under optimal analysis conditions using a single wavelength. We show that the field emitter geometry can be adjusted to the wavelength of the femtosecond laser pulses used to trigger the evaporation by taking into account the optical and thermal properties of the material. The resulting enhanced absorption at the tip apex generates an ultrafast ion emission leading to a surprisingly high mass resolving power and signal over noise ratio on materials having a bad thermal diffusivity. This antenna effect is discussed based on theoretical considerations and a modeling of the laser-tip interaction. It is then demonstrated though experimental results obtained on different specimen geometries.