title: Sub-micron scale patterning of fluorescent silver nanoclusters using low-power laser.
abstract: Noble metal nanoclusters are ultrasmall nanomaterials with tunable properties and huge application potential; however, retaining their enhanced functionality is difficult as they readily lose their properties without stabilization. Here, we demonstrate a facile synthesis of highly photostable silver nanoclusters in a polymer thin film using visible light photoreduction. Furthermore, the different stages of the nanocluster formation are investigated in detail using absorption and fluorescence spectroscopy, fluorescence microscopy, and atomic force microscopy. A cost-effective fabrication of photostable micron-sized fluorescent silver nanocluster barcode is demonstrated in silver-impregnated polymer films using a low-power continuous-wave laser diode. It is shown that a laser power of as low as 0.75 mW is enough to write fluorescent structures, corresponding to the specifications of a commercially available laser pointer. The as-formed nanocluster-containing microstructures can be useful in direct labeling applications such as authenticity marking and fluorescent labeling.
authors.affiliation: Tampere University of Technology, Department of Physics, Tampere, FI-33101, Finland.
authors.forename: Puskal
authors.initials: P
authors.lastname: Kunwar
authors.affiliation: Aalto University, Department of Applied Physics, Espoo, FI-02150, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Hassinen
authors.affiliation: Tampere University of Technology, Department of Physics, Tampere, FI-33101, Finland.
authors.forename: Godofredo
authors.initials: G
authors.lastname: Bautista
authors.affiliation: Aalto University, Department of Applied Physics, Espoo, FI-02150, Finland.
authors.forename: Robin H A
authors.initials: RH
authors.lastname: Ras
authors.affiliation: Tampere University of Technology, Department of Physics, Tampere, FI-33101, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Toivonen