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Wayne State University, Department of Physics and Astronomy

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Martin Luther King Lecture

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Thursday 10 December 1998

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Novel Approaches To Small-Angle Electron Scattering

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Alfred Z. Msezane, Clark Atlanta

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The difficulties of obtaining reliable measurements of the electron DCSs for
atomic, ionic and molecular transitions at and near zero scattering angles are
well documented. Hence, the need for reliable theoretical calculations. Recently,
three theoretical approaches have been derived to investigate and guide
measurements of small-angle, including zero, electron DCSs in atoms
ions and molecules. The first method, the momentum dispersion method (MDM),
based on Regge Pole theory, uses the analytical continuation of the generalized
oscillator strength (GOS) function to obtain the smaller angle, including zero,
date from the more reliably measured larger angular data. The second method,
the forward scattering function (FSF), represents a unique path of the GOS
function to the OSS. It is therefore useful for normalizing the measured
relative electron DCSs through the GOSs. Very recently, a singular
behavior has been found in the electron-atom scattering DCS at small momentum
transfer, K coming from second-order terms and a new generalized Lassettre
expansion has been derived. In forward scattering, it yields a unique
long-sought after curve that normalizes the measured relative DCSs. The
utility of the methodologies is demonstrated using atomic, ionic
and molecular transitions.

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Colloquium starts at 16:00 in Room 245 and lasts about 1 hour
including questions. Refreshments are served at 15:30 in room 245.