Template-Synthesis of Infrared-Transparent Metal Microcylinders: Comparison of Optical Properties with the Predictions of Effective Medium Theory
Abstract
Metal-insulator composites of varying metal volume fraction have prepared by electrochemical deposition of gold into porous, aluminum oxide membranes. The cylindrical pore array structure of the host oxide serves as a template for the formation of Au particles ca. 0.26 gm in diameter with lengths ranging from 0.3 gm to 3 gm depending on deposition time. The composites display a significant transparency in the infrared spectrum between 2000 and 4000 cm- 1. The Au volume fraction and effective medium theory screening parameter K were estimated from scanning electron microscopic analyses of cylinder dimensions and orientations in the composite membranes. Comparison -of experimental spectra with those calculated using Maxwell-Garnett or Bruggeman theories indicates that neither approach is entirely satisfactory. The spectra are consistent, however, with retarded polarization effects due to non-negligible Au particle separation distances in the composites.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 20, 1992
- Accession Number
- ADA253267
Entities
People
- C. A. Foss Jr.
- C. R. Martin
- M. J. Tierney
Organizations
- Colorado State University