Surface Plasmon Resonance Responses of Au-SnO x Nanocomposite Films
- PDF / 752,030 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 39 Downloads / 250 Views
1208-O18-20
Surface Plasmon Resonance Responses of Au-SnOx Nanocomposite Films Dongfang Yang Industrial Materials Institute, National Research Council Canada, 800 Collip Circle, London, ON, Canada N6G 4X8 ABSTRACT Au-SnOx nanocomposite thin films composed of gold nanoparticles embedded in SnOx matrix were prepared by pulsed laser deposition technique and their crystal structure, morphology and chemical composition were evaluated by low angle X-ray diffraction, fieldemission scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. For the nanocomposite films with high Au percentage, the surfaces of nanocomposite films are very smooth, while for the films with low Au percentage, the films consist of many embedded Au nanoparticles with particle size of 5-20 nm. The XRD results revealed that in the nanocomposite films Au existed in a polycrystalline phase while SnOx in an amorphous phase. Surface plasmon resonance (SPR) responses of the Au-SnOx nanocomposite thin films were investigated as functions of Au percentage and film thickness in the Kretschmann geometry of attenuated total reflection using a polarized light beam at the wavelength of 640 nm. The reflectance minima (SPR dip) of SPR responses of the Au-SnOx nanocomposite films appeared at higher values of incident angle than that of a pure Au film and as the Au percentage decreases the SPR angles shift to higher values and the widths also become broader. The potential use of Au-SnOx nanocomposite films for SPR gas sensing was discussed. INTRODUCTION Surface plasmons are surface electromagnetic waves that propagate to and parallel along with a metal/dielectric interface. Noble metal thin films (~50 nm) such as gold (Au) are commonly used as the platform for supporting the surface plasmon waves, which can be excited in a resonant manner by a visible or infrared light beam from a glass prism in either Otto [1] or Kretschmann [2] configurations. Surface plasmon resonance (SPR) phenomena at the noble metal/dielectric interface have enabled a vast array of applications such as surface enhanced spectroscopes [3], and biological and chemical sensing [4, 5]. Nanocomposite [6] thin films formed by noble metal nanoparticles embedded in a dielectric matrix also show SPR phenomenon due to collective excitations of conduction electrons in metal nanoparticles when photons are coupled to the metal particle–dielectric interface. The metal-dielectric nanocomposites offer a high degree of flexibility, and the SPR response can be optimized for specified applications by proper choice of constituents, film thickness, metal particle concentration, size, shape, and orientation. In this work, Au-SnOx composite films of various Au content and thickness were prepared by pulsed laser deposition technique, and characterized by low angle X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS). SPR responses of the nanocomposite films were investigated as functions of
Au percentage and film thickness in
Data Loading...
