Plasmonics Poster Session
Tuesday 16 Oct 2007 06:00 PM - 08:00 PM
Room 4C
PL-TuP6

Single-Nanoparticle Light-Scattering Spectra of Flat Gold Nanoparticles (FGNPs):
A Study of the Effect of Nanoparticle Treatment

W.D. Tennyson, C.E. Allen, D.S. Hartnett, M.D. McCutchen, D.H. Dahanayaka, L.A. Bumm

We have investigated the effects of a range of treatments on the surface plasmon modes of individual FGNPs using single-nanoparticle far-field light-scattering spectroscopy. We have explored thermal annealing, surface cleaning, and nanomechanical manipulation of the FGNPs. We can directly measure the effect of the treatments to an individual nanoparticle by correlating the before-and-after spectra with before-and-after microscopy (AFM and SEM). Finding the same nanoparticle again and again can be a significant barrier in correlation, however we have developed a photolithograpically- prepared addressed-grid system to assist finding the particles in multiple measurement platforms. This method also allows facile correlation of the light-scattering spectra to size, shape, thickness, and local environment.

2006

APS March Meeting
13-17 Mar 2006, Baltimore, MD

Session D10: Focus Session: Physical Chemistry of Nanoscale System III

2:30 PM–5:18 PM, Monday, March 13, 2006
Baltimore Convention Center - 302
Abstract: D10.00002 : 3:06 PM–3:18 PM

Spectroscopic Near-Field Imaging of Flat Gold Nanoparticles

L.A. Bumm, D.H. Dahanayaka, D.W. Kelle, D.J. Wasielewski, E.S. Day, D.R. White
(OU Physics & Astronomy)
B.S. Prall, M. Achermann, V.I. Klimov
(Los Alamos Nation Laboratory)

Using a white-light near-field scanning optical microscope (NSOM) we demonstrate near-field imaging and local plasmon spectroscopy of flat gold nanoparticles (FGNPs). These nanoparticles are atomically-flat single crystal plates with well defined shapes ranging from equilateral triangles to regular hexagons, which include intermediate truncated triangle shapes. NSOM images reveal the FGNP plasmon mode structure and its dependence on FGNP size and shape. Moreover, spatially resolved spectroscopy shows position dependent coupling to different plasmon modes.

 

231st ACS National Meeting
26-30 Mar 2006, Atlanta, GA

Poster COLL 212

Preparation and characterization of optically-resonant atomically-flat nanosurface substrates for scanning tunneling microscopy (STM)

Daminda H. Dahanayaka, David W. Kelle, Daniel J. Wasielewski, Emily S. Day, Daniel R. White, and Lloyd A. Bumm

Flat gold nanoparticles (FGNPs) supported on indium tin oxide (ITO) coated glass can be used as optically-resonant atomically-flat substrates for STM studies. We discuss preparation of the FGNPs and a simple method for depositing them on ITO supporting substrates. Characterization with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) shows that FGNPs can be prepared 100–5000 nm across with shapes that range from triangular to hexagonal with thicknesses of 15-25 nm. Converging-beam electron diffraction confirms that the crystallographic orientation of large facet is in {111} direction and the sides are in <211> directions. Single-particle dark-field scattering spectroscopy and UV-vis-NIR spectrophotmetry show the quadrapole plasmon resonance ~800 nm and the dipole plasmon resonance further in the NIR which are size and the shape dependent. The addition of Polyvinylpyrrolidone (PVP) as a stabilizer during growth has a profound effect on the particle morphology, apparently slowing growth in the <211> edge directions.

Division of Colloid & Surface Science
Symposium Honoring ACS Adamson Award Winner Steven Bernasek
Nanostructures, Facets and Molecular Imaging
Tuesday 28 Mar 2006 8:30-11:00

COLL 352

High-resolution scanning probe microscopy of optically-resonant atomically-flat nanoparticle substrates

Daminda H. Dahanayaka, Daniel J. Wasielewski, Emily S. Day, David W. Kelle, Daniel R. White, Lloyd A. Bumm
(OU Physics and Astronomy)
Marc Achermann, and Victor I. Klimov
(Los Alamos National Laboratory)

We demonstrate molecularly-resolved scanning tunneling microscopy (STM) of self assembled monolayers (SAMs) on flat gold nanoparticles (FGNPs) supported on indium tin oxide (ITO) coated glass. The FGNPs are atomically-flat single crystals with large {111} surfaces which expose only 3-4 atomic layers. These novel substrates are simple and inexpensive to prepare. They have the added advantage over conventional Au{111} substrates (bulk single crystals and Au thin films on mica) that they are also optically-resonant plasmonic antenna. We have also imaged the plasmon mode structure of FGNPs using spectrally resolving white-light scanning near-field optical microscopy (NSOM).

 

2006 MRS Spring Meeting
17-21 Apr 2006, San Francisco, CA

N3.5

Atomically-Flat Nanophotonic Antennae: optically resonant gold nanoparticle substrates for single-molecule optoelectronics

D. H. Dahanayaka, J. X. Wang, D. J. Wasielewski, D. W. Kelle, E. S. Day, D. R. White, G. D. Lian, L. A. Bumm

Supported flat gold nanoparticles (FGNPs) are optically resonant substrates for high-resolution scanning tunneling microscopy (STM). These are atomically-flat single-crystal plates with large {111} faces that are composed of only a few atomic terraces. The nanoparticles are prepared using standard solution techniques and then deposited on indium tin oxide (ITO) coated glass substrates. The nanoparticles range in size from tens to thousands of nanometers and have been characterized by STM, NSOM, SEM, TEM, and dark-field spectroscopy. These are excellent substrates for molecularly-resolved STM imaging of alkanethiol self-assembled monolayers (SAMs). We demonstrate that these FGNP/ITO substrates can be used as photonic antenna for STM single-molecule optoelectronic measurements of guest molecules supported by the host SAM.

Microscopy and Microanalysis 2006
30 Jul-03 Aug 2006, Chicago, IL

P01.3 (09:00-09:15)

Preparation and Characterization of Optically-Resonant Atomically Flat Nanosurface Substrates for High-Resolution Scanning Probe Microscopy of Single Molecules

D. H. Dahayanaka, D. W. Kelle, D. J. Wasielewski, E. S. Day, D. R. White, T. D. Mishima, C. M. Waite, J. L. Moore, R. L. Halterman, L. A. Bumm

The scanning tunneling microscopy (STM) has been broadly applied to measure electronic characteristics of individual molecules supported in an inert monolayer matrix, which is typically grown on gold thin films on mica (Figure 1) or bulk single crystal substrates [1]. Although these substrates are excellent for electronic measurements, they are not optically transparent which can complicate optical measurements. Flat gold nanoparticles (FGNPs) supported on indium tin oxide (ITO) coated glass (Figure 2a) can be used as optically-resonant atomically-flat substrates for STM studies. We discuss preparation and characterization of the FGNPs. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) shows that FGNPs can be prepared 100–5000 nm across with shapes that range from triangular to hexagonal with thicknesses of 15–25 nm. In-focus multiple dark-field TEM imaging [2] confirms that the crystallographic orientation of the large facet is {111} and the edges are in <211> directions as seen in Figure 2b. Single-particle dark-field scattering spectroscopy and UV-vis-NIR spectrophotometry show the quadrupole plasmon resonance ~800 nm [3] and the dipole plasmon resonance further in the NIR, which are size and the shape dependent [4]. The addition of polyvinylpyrrolidone (PVP) as a stabilizer during growth effects the particle morphology, apparently slowing growth in the <110> directions (Figure 3a & b). Also we demonstrate that single molecule electronic measurements can be performed using atomically-flat gold nanoparticles (FGNPs) supported on indium tin oxide coated glass as an alternative to traditional Au{111} substrates.

NFO-9
9th International conference on near-field optics, nanophotonics and related techniques
10-15 Sep 2006, Lausanne, Switzerland

Near-field spectroscopy and imaging of flat gold nanoparticles

M. Achermann, B. S. Prall, V. I. Klimov
Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

D. H. Dahanayaka, D. Wasielewski, L. A. Bumm
Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA

K. L. Shuford, G. C. Schatz
Department of Chemistry, Northwestern University, Evanston, IL 60803, USA

Nanoscale metallic structures are promising substrates for single molecule spectroscopy because of their ability to enhance optical fields at morphology-controlled surface plasmon (SP) frequencies. To exploit this effect SP frequencies and spatial distributions of SP modes have to be known. Here, we present spectrally and spatially resolved near-field (NF) measurements of flat gold nanoparticles (FGNPs) using a white-light NF optical microscope [1]. The nanoparticles are atomically-flat single crystal plates with well defined shapes ranging from equilateral triangles to regular hexagons. FGNPs have a typical thickness of a few tens of nm’s and a lateral extension of hundreds of nm’s, much larger than the spatial resolution of our NF tip. In the imaging mode, we measure the spectrally integrated transmission while scanning over the FGNPs (Fig.1 a and b). We find that small particles have minimum transmission in the center of the particle (Fig.1 a), whereas larger particles exhibit more complex patterns (Fig.1 b), suggesting that higher order plasmon modes are excited. In the spectroscopy mode, we position the NF tip over a specific location of the FGNP and measure the transmitted white-light spectrum I. In comparison with a reference spectrum, I0, we determine the extinction spectrum, Q=-ln(I/I0), of FGNPs. We find that the measured extinction spectrum of the triangle in Fig.1 a deviates significantly from the one based on calculations of an extended gold film with the same thickness. We attribute the deviation to the excitation of plasmon modes. The difference spectrum between the measured and calculated extinction spectra reveals a typical spectrum of a nanoparticle plasmon [1] with a plasmon resonance at the zero-crossing (~2.05eV). We will show that NSOM images and spectra depend significantly on FGNP sizes and shapes indicating the excitation of different, morphology-controlled plasmon modes. Moreover, we will compare the experimental results with discrete dipole approximation calculations.