Production Of 1s2s2p ^{4}P States By Transfer-Loss Cascades In O^{5+} Collisions With He And H_{2} Targets
T.J.M. Zouros^{1,2} and B. Sulik, L. Gulyás, A. Orbán^{3}
1) Dept. of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete, Greece
2) Institute of Electronic Structure and Laser, P.O. Box 1527, 71110 Heraklion, Crete, Greece
3) Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen, Hungary
Single differential cross-sections for transfer-loss (TL) leading to the production of O^{5+}(1s2s ^{3}S)nl ^{4}L states were computed for 0.2 - 1.2 MeV/u collisions of O^{5+}(1s^{2}2s) ions with He and H_{2} targets. At these collision energies, 1s loss is significant and electron transfer to n = 3 - 4 levels is dominant. Furthermore, due to spin conservation, quartet states can only be populated by TL. Within the independent particle model, the probability of 1s electron loss from O^{5+}(1s^{2}2s) projectiles was calculated using the semi-classical approach, while the probability for electron transfer to the O^{5+}(1s2s ^{3}S)nl ^{4}L states (n>=2) was computed using the continuum distorted wave (CDW) approximation. The majority of states with n > 2, can be assumed to have su±cient time to even- tually decay with an almost 100% probability to the long-living metastable 1s2s2p ^{4}P level via a much faster sequence of electric dipole transitions, thus establishing an upper limit to such cascade contributions. The inclusion of this cascade feeding is found to lead to a strong enhancement in the production of the 1s2s2p ^{4}P states, particularly for collisions with the H_{2} target, thus reducing dramatically the existing two-order of magnitude discrepancy between older TL calculations (for n = 2 only) and existing zero-degree Auger projectile electron spectroscopy measurements.
This work was supported by the
Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences,
Office of Science,
U.S. Department of Energy.
Submitted to ISIAC, July 2005 in Rio de Janeiro, Brazil.
A preprint of this paper is available in Adobe Acrobat format.
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