Department of Physics Colloquium on February 20, 2002

Suresh C. Sharma

Department of Physics, The University of Texas at Arlington, Arlington, Texas

A “Progress Report” on our recent efforts in the following two areas of research

EFFECTS OF HIGH PRESSURE ON THE ELECTRONIC, STRUCTURAL, AND VIBRATIONAL PROPERTIES OF C₆₀-BASED FULLERENES

I will discuss recent developments leading to the establishment of our new research facility to probe the electronic, structural, and vibrational properties of materials, in particular C₆₀-based fullerenes under extremely high pressures. We have designed, set-up, and tested the performance of several instruments and techniques, including ultra-high vacuum photoemission spectroscopy, high resolution Raman scattering, high pressure (>20 GPa) diamond anvil cell, x-ray diffraction measurements with diamond anvil cell, low-temperature (10 to 295K) electrical conductivity measurements, and thin film growth. I will also present and discuss our preliminary results on: 1) Photoemission spectroscopy measurements of the valence band structures of polymerized thin films of C₆₀ and La_0.1C₆₀^, 2) Raman spectroscopy measurements of the vibrational properties of C₆₀ compressed under high pressures in a diamond anvil cell.

Supported by the Department of Energy and The Welch Foundation

OPTICAL PROPERTIES (SWITCHING BEHAVIOR) OF NANOMETER-SIZE LIQUID-CRYSTAL DROPLETS DISPERSED IN A POLYMER MATRIX

Polymer-dispersed liquid crystals (PDLC) constitute an important class of materials with applications in electrically switchable optical devices. For example, light transmission through such a device can be controlled precisely by the application of relatively small voltages. I will discuss fabrication of a simple device, present results on its switching behavior, and speculate on its potential new applications.

Supported by the Texas Advanced Technology Program