AVS 46th International Symposium
    Applied Surface Science Division Friday Sessions
       Session AS-FrM

Paper AS-FrM2
Atmospheric Electron X-ray Spectrometer

Friday, October 29, 1999, 8:40 am, Room 6A

Session: New or Improved Surface Related Analytical Techniques
Presenter: J. Feldman, Jet Propulsion Laboratory
Authors: J. Feldman, Jet Propulsion Laboratory
J.Z. Wilcox, Jet Propulsion Laboratory
T. George, Jet Propulsion Laboratory
D.N. Barsic, Caltech
A. Scherer, Caltech
T. Doll, Caltech
Correspondent: Click to Email
Atmospheric Electron X-Ray Spectrometer (AEXS) J. Feldman, J. Z. Wilcox, and T. George, Jet Propulsion Laboratory D. N. Barsic, T. Doll, and A. Scherer, Electrical Engineering and Applied Physics, Caltech Abstract The Atmospheric Electron X-ray Spectrometer (AEXS) is a new miniature instrument being developed for in situ elemental analysis of surfaces. The key component of the instrument is a microfabricated silicon nitride membrane. This electron transmissive membrane serves to isolate the high-vacuum electron column from the ambient atmosphere. An electron beam generated and focused in the column is transmitted through the membrane to impinge on the sample in the ambient atmosphere. The electron beam excites characteristic x-rays, which are analyzed to determine the elemental composition of the irradiated portion of the sample. The power of this type of analysis is that samples can be analyzed in situ without being introduced into a vacuum chamber as in traditional scanning electron microscopy (SEM). Due to the return ionization path through the atmosphere, sample preparation is unnecessary even for non-conductive samples. This talk describes the development and current status of the AEXS. Initial spectra were obtained in ambient Earth atmosphere with a spot size of less than 1mm and a spectrum acquisition time of a few minutes. The physical properties of a number of candidate low atomic number microfabricated membranes, including electron and x-ray transmissivity, will be discussed. The prototype instrument is designed to be portable, with a mass of 1 kg. The high spatial resolution of the AEXS (as compared to alpha particle or x-ray fluorescence instruments) will enable mapping of compositional heterogeneities at a grain size level. In addition to applications in planetary exploration, the AEXS also has potential applications in industrial process monitoring and quality control.