AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeM

Paper SS-WeM2
Development of a Time-of-Flight HREELS Using Pseudorandom Modulation

Wednesday, November 6, 2002, 8:40 am, Room C-112C

Session: New Opportunities and Technique Innovations
Presenter: R.H. Jackson, University of Maine
Authors: R.H. Jackson, University of Maine
Z. Yang, University of Maine
L.J. LeGore, University of Maine
P. Kleban, University of Maine
B.G. Frederick, University of Maine
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We have constructed a prototype high resolution Time-of-Flight HREELS utilizing pseudorandom modulation. The instrument is comprised of an LK-3000 HREELS, a custom designed TOF analyzer with a double mu-metal shielded 1.5m flight tube, a Bradbury-Neilsen Gate modulator, a microchannel plate detector, and a Fast Com Tek time to digital converter with 250 ps time bins. The electron optics have been shown to pass a beam of electrons to the detector with energies as low as 0.5eV over a 1m flight length. The TOF spectra are recovered using the Lucy maximum likelihood deconvolution algorithm. Initial measurements show that the method can recover well resolved <4meV peaks at 6eV flight energies to within the capability of the current data acquisition electronics. We will present the methodology for using and calibrating the instrument and show loss spectra of PTFE films comparing the TOF and conventional spectra.