Title

Preparation of Two-Dimensional Arrays of Ag Nanopaticles for Laser Interrogation.

Authors

Paul Chung

Document Type

Article

Publication Date

1999

Abstract

A nanoparticle is a collection of thousands of atoms in a typically spherical shape with a diameter of 1 to 100 nm. These particles are bits of matter that lie somewhere between the atom and the bulk. Their chemical and physical properties are of considerable importance in understanding finite-sized systems. Silver nanoparticles passivated with dodecanethiol have been synthesized. A tremendous advantage of forming passivated nanoparticles is the ease of particle size-selection with organic solvents. Size-selected silver nanoparticles have been characterized by Ultraviolet-Visible Absorption and Fourier Transform Infrared Spectroscopies. These particles have an average diameter of approximately 40 nm. A two-dimensional crystalline array of Ag nanoparticles will be formed on a Langmuir Trough. This array or monolayer will be transferred by the Langmuir-Schaefer method to a clean glass slide. The supported array will be mounted in a high vacuum chamber for laser interrogation. In bulk metal, the energy of excited electrons will be dissipated by the phonons or lattice modes. In a small particle, the lattice modes are quite different than in the bulk and may not be as effective in quenching the electrons. Therefore, in a finite-sized particle, it is hypothesized that the excited electrons will escape the metal. Low intensity light of the second harmonic of a Nd:YAG laser (532 nm) will be directed onto the array to excite electrons and the intensity of the ejected electrons will be measured.

Advisor

E. M. Spain

Department

chem

Support

Support provided by:Research Corporation, American Chemical Society-PRF, National Science Foundation, Dreyfus Foundation

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