What controls the composition and the structure of nanomaterials generated by laser ablation in liquid solution?

Abstract

Laser ablation synthesis in liquid solution (LASiS) is a "green" technique that gives access to the preparation of a library of nanomaterials. Bare noble metal spherical particles, multiphase core-shell oxides, metal-semiconductor heterostructures, layered organometallic compounds and other complex nanostructures can be obtained with the same experimental set up, just by varying a few synthetic parameters. How to govern such versatility is one of the current challenges of LASiS and requires a thorough understanding of the physical and chemical processes involved in the synthesis. In this perspective, the fundamental mechanisms of laser ablation in liquids are summarized, organized according to their temporal sequence and correlated with relevant examples taken from the library of nanomaterials disclosed by LASiS, in order to show how synthesis parameters influence the composition and the structure of products. The resulting framework suggests that, to date, much attention has been devoted to the physical aspects of laser-matter interaction and to the characterization of the final products of the synthesis. Conversely, the clarification of chemical processes active during LASiS deserves more research efforts and requires the synergy among multiple investigation techniques.

Coexistence of plasmonic and magnetic properties in Au89Fe11 nanoalloys

“…In LASiS, a difference between the stoichiometry of alloy nanoparticles and the original alloy target is observed when the two elements in the alloy have different reactivities or different vaporization heats. 48,53,54 Here, the vaporization heats of gold and iron are similar (324 and 340 kJ mol À1 , respectively), but iron can react with oxygen that is dissolved in non-deaerated solvents, as reported for instance during LASiS of NiFe NPs. 55 Transmission electron microscopy (TEM) images of the AuFeNP solution just aer LASiS but prior to the addition of EDTA/PEG indicated the presence of iron oxide and amorphous phases ( Fig.…”

“…Using this top-down approach, [48][49][50][51][52] we were able to overcome the thermodynamic limitations to the room-temperature formation of Au-Fe alloys. 48,53 The formation of nanoparticles was immediately visible from the reddish color of the solution, which became purple aer a few hours due to particle aggregation. Aer LASiS, an aqueous solution containing disodium ethylenediaminetetraacetic acid (EDTA) and thiolated polyethyleneglycol (PEG) was added to the AuFeNP dispersion in ethanol and the solution was kept at 60 C for 1 hour (Fig.…”

“…Planar defects in fcc metals are usually associated with internal stresses due to rapid cooling, 59 and are typical of LASiS. 48,53 We used energy-ltered TEM (EFTEM) to gather additional information on the elemental distribution of Au and Fe in individual PEG-AuFeNPs. We performed elemental mapping on ve nanoparticles with sizes between 15 and 50 nm by selecting the Au N-edge (83 eV) and the Fe L-edge (708 eV) respectively ( Fig.…”

Cavitation bubble dynamics during pulsed laser ablation of a metallic glass in water

“…This intriguing phenomenon has versa-tile applications ranging from nanoparticle synthesis [1,2], surface cleaning [3] to luminescence [4]. The dynamics of cavitation bubble is of central importance since it reflects the fundamental response of liquid-plasma-solid system to laser ablation, and thus has drawn increasing interest [5][6][7][8].…”

Colloidal Stability of Metal Nanoparticles in Engine Oil under Thermal and Mechanical Load

“…This relatively new technique allows a simple and rapid synthesis of surfactant-free ceramic or metal nanoparticles in various liquids with high nanoparticle productivities [25][26][27][28]. A bulk material, which is immersed in a liquid, absorbs the pulsed laser beam and is evaporated until it condenses as nanoparticles in the surrounding, stabilizing medium [21,29].…”