Synthesis and characterization of selenium nanoparticles obtained by femtosecond pulsed laser ablation in liquid media

In this work, we report on the synthesis of selenium nanoparticles in various solvents via femtosecond pulsed laser ablation in liquids (FPLAL). A Coherent-Vitara laser oscillator producing pulses of 24 fs, 800 nm, and 1–7 nJ, at 80 MHz repetition rate was employed. The nanoparticles (NPs) were generated by FPLAL ablating a high-purity selenium target submerged in different solvents. The ablation time was varied from 1 to 45 min. The NPs were uniformly dispersed in the solution showing a red color due to surface plasmon excitation characteristic of colloidal selenium nanoparticles. The samples were characterized by TEM, UV–Vis, and Raman spectroscopy. TEM images reveal the presence of nanoparticles with sizes ranging from 5 to 200 nm and an effect of the solvent which in one case promotes the formation of amorphous selenium. The UV–Vis absorption spectra of the prepared Se-NPs show a maximum absorption peak at 242 nm attributed to the surface plasmon of Se. Raman spectroscopy shows two bands peaking at 235 and 250 cm −1 , indicating, respectively, the crystalline and amorphous nature of the synthesized nanostructures. The ratio between these two peaks varies depending on the solvents.