  A new instrument for spot profile analysis of electron diffraction - SPA-LEED
- has been set up. The instrument works either with a transparent phosphor
screen for visual inspection of the pattern or in its main mode with a
channeltron for the measurement of the intensity. The diffraction pattern is
recorded with a fixed channeltron position by scanning the beam over the
channeltron aperture using two sets of electrostatic deflection plates. The
scanning range covers about 30{\deg}. The intensity may vary over five orders
of magnitude. The SPA-LEED system was checked with the Si 111 7 x 7 surface. A
full width at half maximum of 0.3% of the normal reflex distance corresponding
to a transfer width of 110 nm is reproducibly obtained. Under optimum
conditions the transfer width rose up to about 200 nm. Initial high resolution
measurements have been performed on the system Pb on Cu 111. The results
demonstrate the possibilities of the new instrument for qualitative and
quantitative analysis.
