title: Upconversion Nanoparticles Synthesized by Ultrashort Pulsed Laser Ablation in Liquid: Effect of the Stabilizing Environment.
abstract: The distinctive feature of upconverting compounds to absorb and emit light in the near-infrared region has made upconverting nanoparticles of great interest in various application fields. Nevertheless, these colloids show a highly hydrophobic behavior, and therefore, the use of a proper stabilizing agent is necessary in most cases. Although few chemical techniques for colloid stabilization are available, it is still difficult to achieve a fully reproducible synthesis method for stable upconverting nanoparticle colloids. In this work, upconversion 18 %Yb:1 %Er:NaYF4nanoparticles were produced by ultrafast pulsed laser ablation in a water and 2-[2-(2-methoxyethoxy)- ethoxy]acetic acid (MEEAA) environment to assess the stabilization effect of the surfactant on the nanoparticle colloid properties. The effects of the laser fluence and MEEAA concentration on the nanoparticles' properties were investigated by TEM, EDS, and emission spectra analyses. The results show that ultrashort pulsed laser ablation in liquid allows generating highly spherical nanoparticles with conserved stoichiometry and optical properties. Moreover, it is possible to obtain colloids with significantly higher stability and preserved optical properties by one-step PLAL processes directly in the MEEAA environment.
authors.affiliation: ALPhANOV, Institut d'optique d'Aquitaine, Rue François Mitterrand, 33400, Talence, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Gemini
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 7, 45141, Essen, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Schmitz
authors.affiliation: ALPhANOV, Institut d'optique d'Aquitaine, Rue François Mitterrand, 33400, Talence, France.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kling
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 7, 45141, Essen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Barcikowski
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 7, 45141, Essen, Germany.
authors.forename: Bilal
authors.initials: B
authors.lastname: Gökce
keywords: nanoparticles; pulsed laser ablation in liquid; surfactants; ultrashort laser pulse; upconversion