Early time dynamics of laser-ablated silicon using ultrafast grazing incidence X-ray scattering

• Published in: Chemical physics letters 2019-12, Vol.736 (C), p.136811, Article 136811
• Main Authors: Hull, C., Raj, S., Lam, R., Katayama, T., Pascal, T., Drisdell, W.S., Saykally, R., Schwartz, C.P.
• Format: Article
• Language: English
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2019.136811

[Display omitted] •Grazing incidence geometry yields scattering from only the laser excited regions of the substrate.•Fragmentation in the ablation plume is seen to occur on a timescale of 20 ps after laser ablation.•Small angle scattering can be used as a tool to characterize the evolution of nanostructures in the ablation plume. Controlling the morphology of laser-derived nanomaterials is dependent on developing a better understanding of the particle nucleation dynamics in the ablation plume. Here, we utilize the femtosecond-length pulses from an x-ray free electron laser to perform time-resolved grazing incidence x-ray scattering measurements on a laser-produced silicon plasma plume. At 20 ps we observe a dramatic increase in the scattering amplitude at small scattering vectors, which we attribute to incipient formation of liquid silicon droplets. These results demonstrate the utility of XFELs as a tool for characterizing the formation dynamics of nanomaterials in laser-produced plasma plumes on ultrafast timescales.