title: Preparation of small size palladium nanoparticles by picosecond laser ablation and control of metal concentration in the colloid.
abstract: We assessed a method for the preparation of small, highly stable and unprotected Pd nanoparticles by picosecond laser ablation in 2-propanol. The nanoparticles can be extracted from 2-propanol by centrifugation and redispersed in water, where a strongly negative ζ-potential assures long term stability. The proposed procedure permits reduction of particle size down to 1.6nm and optimization of the Pd(0):Pd(II) ratio which, in the best cases, was of the order of 6:1. The increase of this ratio with ablation times has been correlated to the high temperature conversion of PdO to metallic Pd by a simple theoretical model. A study of the relationship between colloid absorption at 400nm and Pd concentration permitted the role of PdO in the determination of the UV-vis spectra to be clarified and the limits of the Mie theory for the evaluation of colloid concentration to be established. The absorption at 400nm can be used as a fast method to estimate the Pd content in the colloids, provided that a calibration of the ablation process is preliminarily performed.
authors.affiliation: Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy. Electronic address: emilia.giorgetti@fi.isc.cnr.it.
authors.forename: E
authors.initials: E
authors.lastname: Giorgetti
authors.affiliation: Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy; Department of Physics "E. Fermi", University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Marsili
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cicchi
authors.affiliation: Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy; Department of Chemistry "Ugo Schiff", University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: L
authors.initials: L
authors.lastname: Lascialfari
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: M
authors.initials: M
authors.lastname: Albiani
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: M
authors.initials: M
authors.lastname: Severi
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy; Consorzio INSTM, Via Giusti 9, 50123 Firenze, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Caporali
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: M
authors.initials: M
authors.lastname: Muniz-Miranda
authors.affiliation: Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, 98166 Messina, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pistone
authors.affiliation: Department of Physics "E. Fermi", University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Giammanco
keywords: Laser ablation; Metal clusters; Pd nanoparticles; Pd oxides