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Introduction
Apparatus
Calculations
Results
Contacts
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Figure 4

The Dinner Plate Analogy

fig4-1.gif (3364 bytes) The Dinner Plate Analogy illustrates how we measure collision cross sections. Imagine a known number of plates arranged arbitrarily on a table of known area. We wish to find the area of each plate.
fig4-2.gif (5517 bytes) We throw marbles arbitrarily at the table; some hit the plates and some miss. By measuring the ratio of marbles that hit the plates to the total number of throws we can determine the area (cross section) of each plate.

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In our experiment we want to determine the cross section for a particular kind of excitation event. The molecules of NO are our dinner plates and the electrons replace the marbles. A "hit" is determined by detecting photons of a particular wavelength that are emitted from an collisionally-excited  molecule.
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Layout and Design: Andrew A. Kucheriavy