Electron excitation of optically-allowed transitions in CO{sub 2}, SF{sub 6}, CO, F{sub 2}, and SO{sub 2}
- Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, Georgia 30314 (United States)
Dipole-allowed transitions for the inner-shell {ital C}{sub 1{ital s}}(2{sigma}{sub {ital g}}){r_arrow}2{Pi}{sub {ital u}} in CO{sub 2} and 2{ital t}{sub 1{ital u}}{r_arrow}6{ital a}{sub 1{ital g}}, 2{ital t}{sub 1{ital u}}{r_arrow}2{ital t}{sub 2{ital g}}, and 2{ital t}{sub 1{ital u}}{r_arrow}4{ital e}{sub {ital g}} in SF{sub 6}; for {ital X}{sup 1}{Sigma}{sup +}{r_arrow}{ital A}{sup 1}{Pi} and {ital X}{sup 1}{Sigma}{sup +}{r_arrow}{ital C}{sup 1}{Sigma}{sup +} in CO; for excitation of {ital F}{sub 2}{ital I}{sup 1}{Sigma}{sup +}{sub {ital u}} and the electronic states of SO{sub 2} are investigated at small scattering angles through the generalized oscillator strength using a recent universal function by A. Z. Msezane and I. A. Sakmar. The results cover the electron energy between 20 eV and 2.5 keV. Good agreement with existing experimental data and calculations is obtained for the inner-shell excitation of CO{sub 2} and the 2{ital t}{sub 1{ital u}}-6{ital a}{sub 1{ital g}} transition in SF{sub 6}, implying that dynamic effects are unimportant at small scattering angles. The unmeasured differential cross sections (DCS{close_quote}s) in the angular range of about 0{degree}{le}{theta}{le}2{degree} are found to contribute significantly to the integral cross sections, ranging from 40{percent} to 69{percent} at 300 and 500 eV in CO. The universal function approach provides an independent check of small-angle theoretical and experimental DCS{close_quote}s. Given reliable small-angle DCS{close_quote}s, the universal formula can be used to obtain reasonable values of optical oscillator strengths. Dynamic effects can also be investigated and are shown to be significant in the fourth positive band of CO at 500 eV, even near zero scattering angles. In contrast, dynamic effects are unimportant in the inner-shell excitation of CO{sub 2} at 1290 eV, up to large momentum-transfer-squared values, even though for the transition the first Born approximation should not be applicable.
- OSTI ID:
- 282785
- Journal Information:
- Physical Review A, Vol. 53, Issue 2; Other Information: PBD: Feb 1996
- Country of Publication:
- United States
- Language:
- English
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