• Home
• Application
• Projects
• Previous Programs
  • 2006
    • Program Schedule
    • Events Schedule
    • Participants/Project Abstracts
  • 2007
    • Program Schedule
    • Events Schedule
    • Participants/Project Abstracts
• Links
  • Department of Chemistry
  • NFS REU
  • Analytical Sciences Digital Library
  • ACS Division of Analytical Chemistry

Participants/Project Abstracts

Summer 2006 Bioanalytical Science REU Participants

Chemistry SURF Student - Peter Stavros

BREWSTERS ANGLE CAVITY RING DOWN SPECTROSCOPY

Peter G. Stavros , James Hargrove, David Medina, Karen Muyskens, Mark Muyskens, and Jingsong Zhang
Department of Chemistry, University of California - Riverside , UCR 92521 and The University of Chicago , Chicago , Il 60637 .

Cavity ring down spectroscopy (CRDS) utilizes high reflectivity mirrors to create a long optical path length, by measuring the rate of decay rather than the intensity of absorption gives the instrument robustness to laser power fluctuations and a highly sensitive way of measuring gas and particulate absorptions. Adapting CRDS for thin films promises high sensitivity measurements. Because of the nature of CRDS, the sensitivity is directly related to the time that the light pulse is trapped within the cavity. To maximize the sensitivity, non-absorption losses of the system must be minimized -this includes reflective losses. Reflective losses are minimized at the air interfaces by either normal incidence or at Brewster's angle (BA). Comparing the two, it was determined that the precision needed to minimize scattering at normal incidence was much greater than that of BA, where films tuned as much as 3 ° away provided good sensitivity. Upon this detuning, an interesting oscillation became evident and worthy of further investigation. In order to model this interaction, characterization of the internal reflection and resulting interference was needed. By relating the wavelength with the index of refraction of the material and the internally reflected light, a similar interference pattern was obtained. As a result of this work, the nature of this interference pattern is better understood, but it remains unclear whether or not this can be taken advantage of.

<< Back to Participants/Project Abstracts Main Page