title: Ligand-core NLO-phores: a combined experimental and theoretical approach to the two-photon absorption and two-photon excited emission properties of small-ligated silver nanoclusters.
abstract: We report a combined experimental and theoretical study of the two-photon absorption and excited emission properties of monodisperse ligand stabilized Ag11, Ag15and Ag31nanoclusters in aqueous solutions. The nanoclusters were synthesized using a cyclic reduction under oxidative conditions and separated by vertical gel electrophoresis. The two-photon absorption cross-sections of these protected noble metal nanoclusters measured within the biologically attractive 750-900 nm window are several orders of magnitude larger than that reported for commercially available standard organic dyes. The two-photon excited fluorescence spectra are also presented for excitation wavelengths within the same excitation spectral window. They exhibit size-tunability. Because the fundamental photophysical mechanisms underlying these multiphoton processes in ligand protected clusters with only a few metal atoms are not fully understood yet, a theoretical model is proposed to identify the key driving elements. Elements that regulate the dipole moments and the nonlinear optical properties are the nanocluster size, its structure and the charge distribution on both the metal core and the bound ligands. We coined this new class of NLO materials as "Ligand-Core" NLO-phores.
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France. rodolphe.antoine@univ-lyon1.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Russier-Antoine
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France. rodolphe.antoine@univ-lyon1.fr.
authors.forename: Franck
authors.initials: F
authors.lastname: Bertorelle
authors.affiliation: Univ Lyon, Ecole Normale Supérieure de Lyon, CNRS Université Lyon 1, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, Lyon, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Calin
authors.affiliation: Center of excellence for Science and Technology-Integration of Mediterranean region (STIM) at Interdisciplinary Center for Advanced Sciences and Technology (ICAST), University of Split, Meštrovićevo šetalište 45, HR-21000 Split, Republic of Croatia and Faculty of Science, University of Split, Teslina 12, HR-21000 Split, Republic of Croatia.
authors.forename: Željka
authors.initials: Ž
authors.lastname: Sanader
authors.affiliation: Center of excellence for Science and Technology-Integration of Mediterranean region (STIM) at Interdisciplinary Center for Advanced Sciences and Technology (ICAST), University of Split, Meštrovićevo šetalište 45, HR-21000 Split, Republic of Croatia.
authors.forename: Marjan
authors.initials: M
authors.lastname: Krstić
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France. rodolphe.antoine@univ-lyon1.fr.
authors.forename: Clothilde
authors.initials: C
authors.lastname: Comby-Zerbino
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France. rodolphe.antoine@univ-lyon1.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France. rodolphe.antoine@univ-lyon1.fr.
authors.forename: Pierre-François
authors.initials: PF
authors.lastname: Brevet
authors.affiliation: Center of excellence for Science and Technology-Integration of Mediterranean region (STIM) at Interdisciplinary Center for Advanced Sciences and Technology (ICAST), University of Split, Meštrovićevo šetalište 45, HR-21000 Split, Republic of Croatia and Department of Chemistry, Humboldt Universitat zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany. vbk@cms.hu-berlin.de.
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bonačić-Koutecký
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Lyon, France. rodolphe.antoine@univ-lyon1.fr.
authors.forename: Rodolphe
authors.identifier: http://orcid.org/0000-0001-5682-8550
authors.initials: R
authors.lastname: Antoine