Femtosecond-laser-induced Ablation of an Aluminum Target Probed by Space- and Time-resolved Soft X-ray Absorption Spectroscopy

Abstract

Laser ablation involves phase transitions that produce an ablation plume consisting of various states of matter, namely solid, liquid, vapor, and plasma. This plume plays an important role in the deposition of thin films [1], the formation of nanoparticles [2], and other processes. It is important to investigate this ablation plume at the atomic level not only for a basic study of laser ablation dynamics but also to provide a better understanding of such processes. Because the plume evolves spatially over time, space- and time-resolved measurements are also required. One atomic-level diagnostic method is X-ray absorption spectroscopy (XAS). This involves an element-specific probe of the local structure in a material and provides information about its electronic and atomic structure. An important advantage of this technique is that a wide variety of solid, liquid, and gaseous samples can be examined directly and nondestructively. Furthermore, we can combine this technique with an ultrafast X-ray probe generated by femtosecond-laser-induced plasma [3]–[6], and this makes time-resolved XAS suitable for the study of laser ablation processes.