Electron-impact excitation of the potassium atom. [eV range]
Absolute optical electron-impact excitation functions for 24 transitions of the sharp, principal, diffuse, and fundamental spectral series of potassium have been measured. The determination of the density of the potassium vapor in the collision chamber was made by measuring the degree of transmission, by the vapor, of potassium resonance radiation generated externally in a fluorescence cell. Direct excitation functions were determined for 14 states (5S, 6S, 7S, 8S, 4P, 5P, 6P, 7P, 3D, 5D, 6D, 5F, 6F, and 7F) with the aid of known radiative-transition probabilities. Theoretical calculations of these same 14 excitation functions, as well as 4D and 4F, were carried out by means of the Born approximation. The 4P, 5P, 5S, 3D, and 4D direct excitation functions at intermediate energies (10--25 eV) were also calculated by the method of multistate close coupling, neglecting projectile--target-electron exchange. The high-energy (above 100 eV) Born-approximation cross sections agree with the experimental results for 4P and for all S states, but are lower than experimental results, by 30--40%, for the D and F states. At intermediate energies the close-coupling excitation calculations agree well with the experimental excitation functions for 4P and 5P, but are significantly higher than experimental values for 5S and 3D. The discrepancies between the experimental and theoretical results are probably due to a combination of systematic experimental errors, errors in the available transition-probability values, and errors in the theoretical excitation functions introduced by the use of approximate excited-state wave functions (Hartree-Fock-Slater), by the neglect of projectile--target-electron exchange. The polarization of the 4P-4S and 3D-4P radiation produced by electron impact was measured, and the results were used to determine the direct excitation functions of the separate magnetic sublevels of the 4P state.
- Research Organization:
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706
- OSTI ID:
- 5865443
- Journal Information:
- Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 20:4; ISSN PLRAA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METALS
ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
EMISSION SPECTRA
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EV RANGE 10-100
EV RANGE 100-1000
EXCITATION
EXCITATION FUNCTIONS
METALS
POLARIZATION
POTASSIUM
SPECTRA