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II) Electron-Impact Excitation out of the ground state of Atoms
D. Pressure Effects
Low & High Pressure Cross sections
As before, at low pressure there are only two means of populating level-i:
Both the population density, n(i), and the intensity I(i-->l) will both be directly proportional to the ground state number density, n(g), and thus the pressure.
Graphically, if we plot these quantities as a function of pressure:
As we increase the gas pressure further, the measured intensity is no longer linear. The cross section seems to depend on the number density of target atoms.
|last updated: May-15-1997|