title: γ-Al2O3 nanoparticles synthesised by pulsed laser ablation in liquids: a plasma analysis.
abstract: Pulsed laser ablation has proved its reliability for the synthesis of nano-particles and nano-structured materials, including metastable phases and complex stoichiometries. The possible nucleation of the nanoparticles in the gas phase and their growth has been little investigated, due to the difficulty of following the gas composition as well as the thermodynamic parameters. We show that such information can be obtained from the optically active plasma during its short lifetime, only a few microseconds for each laser pulse, as a result of a quick quenching due to the liquid environment. For this purpose, we follow the laser ablation of an α-Al2O3 target (corindon) in water, which leads to the synthesis of nanoparticles of γ-Al2O3. The AlO blue-green emission and the Al(I) (2)P(0)-(2)S doublet emission provide the electron density, the density ratio between the Al atoms and AlO molecules, and the rotational and vibrational temperatures of the AlO molecules. These diagnostic considerations are discussed in the framework of theoretical studies from the literature (density functional theory). We have found that starting from a hot atomized gas, the nucleation cannot occur in the first microseconds. We also raise the question of the influence of water on the control of the stoichiometry.
authors.affiliation: PRES-Université de Lyon, F-69361 Lyon, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Lam
authors.forename: David
authors.initials: D
authors.lastname: Amans
authors.forename: Frederic
authors.initials: F
authors.lastname: Chaput
authors.forename: Mouhamed
authors.initials: M
authors.lastname: Diouf
authors.forename: Gilles
authors.initials: G
authors.lastname: Ledoux
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mary
authors.forename: Karine
authors.initials: K
authors.lastname: Masenelli-Varlot
authors.forename: Vincent
authors.initials: V
authors.lastname: Motto-Ros
authors.forename: Christophe
authors.initials: C
authors.lastname: Dujardin