A dual nanosecond-pulsed laser setup for nanocomposite synthesis-Ag nanoparticles in Al_2O_3/VO_2 matrix

摘要

A reactor based on the association of a pulsed laser nanoparticle source and a pulsed laser deposition process is presented. This process uses two independent nano-second pulsed lasers. The nanoparticle source, based on a quenching of a plasma plume, is accurately described. Nanoparticles produced by this dedicated laser-based source present intrinsically quasi-monodisperse size in the range of 1-10 nm. This monodispersity is essential to correlate nanoparticle size and related properties. For silver nanoparticles, a change in a characteristic parameter, the opening t-time of the quenching valve, (conditioning the species residence time) from 280,us to 580 mu s, leads to a nanoparticle size increase by a factor of about two (from 2.5 nm to 4.3 nm). Consequently, the size modulation allows the synthesis of nanoparticles and resulting nanocomposites which present drastically different properties. A kinetic model in good agreement with the experiment shows two nanoparticle growth modes, i.e., a monomer accretion and a cluster coagulation. Revealing the potential of the pulsed laser reactor, different nanocomposite materials constituted by Ag nanoparticles associated with oxide thin films (Al2O3, VO2) matrix are optically characterized. A surface plasmon resonance (lambda(SPR)) in the visible-near IR regime is evidenced, and huge modulation and tunability are obtained linked to the host matrix nature and nanocomposite architecture. Moreover, the metal insulator transition capacity of a vanadium dioxide matrix makes lambda(SPR) tunable as a function of temperature. This type of nanocomposite appears pertinent for their great potential in both nano-photonics and nano-sensors.