The excitation of Fe XVII by electron impacts

Abstract

The cross-sections for the excitation of Fexvu are computed using the Coulomb-Born approximation. For the excitation of the configurations 2p ~ 3s, 2p 5 3p and 2p 5 3d, the intermediate coupling scheme is used, while an extrapolation is made for the excitation of the 2s 2p 6 3s, 2s 2p 6 3p and 2s 2p 6 3d configurations from the results obtained earlier in the lithium-like ions. It is found that the excitation cross-section Q (2p 61S0--+2p5 3p 1S0) is fairly large and partly removes the disagreement between the theoretical and experimental intensity-line ratios.

New Benchmark of X-ray Line Emission Models of Fe XVII

“…Theoretical study of Fe XVII X-ray lines and their applications in astronomy have a long history. Bely & Bely (1967) obtained the excitation cross sections of 2p 5 3l configurations using the Coulomb-Born approximation. Loulergue & Nussbaumer (1973, 1975 developed collisional radiative models of Fe XVII and Ni XIX with DW collision strengths, and compared the resulting line intensities with solar observations.…”

Calculated solar X-radiation from 1 to 60 �

“…The absorption oscillator strengths have often been taken from the tables of Wiese et al (1966Wiese et al ( , 1969 and sometimes from other sources (Evans and Pounds, 1968;Bely and Bely, 1967;Walker and Rugge, 1969;Froese, 1967;Austin et al, 1966;Widing and Sandlin, 1968;Fawcett et al, 1968). The f-values of the innershell K~ transitions have been calculated by House (1969).…”

“…e Calculated with tables from Bates and Damgaard (1949) (radial transition integral) and from Goldberg (1935Goldberg ( , 1936 and Allen (1963) (relative multiplet strength). Bely and Bely (1967). g Estimated from measured line intensities (Walker and Rugge, 1969) and theoretical data for 2214.25 and 14.40 (Evans and Pounds, 1968).…”

“…The parameters A, B, and C, have been derived from various theoretical and experimental results for hydrogen-like ions (Burgess et al, 1970;Jacobs, 1971Jacobs, , 1972Moiseiwitsch and Smith, 1968), helium-like ions (Bely, 1968;Elton and K6ppen-doffer, 1967;Gabriel and Jordan, 1969;Kunze et al, 1967;Moiseiwitsch and Smith, 1968;Rugge and Walker, 1971;Walker and Rugge, 1970), lithium-like ions (Bely, 1966), and neon-like ions (Bely and Bely, 1967). In another paper (Mewe, 1972b) this will be discussed in more detail.…”