Experimental cross sections for electron-impact ionization of iron ions:Fe5+,Fe6+<

Abstract

Absolute cross sections have been measured for electron-impact ionization of Fe ions of initial charges 5+, 6+, and 9+ from below' threshold to 1500-eV collision energies. Distorted-eave calculations including only direct ionization from ground-state ions underestimate the measured peak cross sections by 60 -70% due to the effects of metastable states and contributions of excitation autoionization to the total cross sections. Ionization rate coefficients and fitting parameters are presented for this data and for Fe+ and Fe~+.

X-ray emission from thin plasmas

“…The measurements found for the cobalt sequence are Montague et al (1984a) for Ni ii and Gregory et al (1986) for Cu iii, which are well fitted. Co i was fitted with data of Tawara (2002) taken from CHIANTI (D07) and Zn iv with the extrapolation of Ni ii and Cu iii.…”

“…We use the Pindzola et al (1991) theoretical calculations for Ni iii, which are in good agreement with Stenke et al (1999) at high energies; and Gregory et al (1986) for Cu iv. The rest of the elements of the sequence are interpolated.…”

“…There are no apparent reasons for discarding any of the three sets and therefore we decided to include all of them. For Fe vii we use the sets of Gregory et al (1986) and Stenke et al (1999) and forNi ix the calculations of Pindzola et al (1991) and Wang et al (1988).…”

“…For the manganese sequence (3p 6 3d 7 ) elements 3d shell DI cross-section, we use the theoretical calculation of Younger (1983) for Fe ii and the measurements of Gregory et al (1986) for Ni iv. Since the Fe ii element has a ground state configuration of 3d 6 4s, we considered the measurements of the total DI crosssection of Montague et al (1984a) for subtracting the contribution of the rest of the inner-shells and for obtaining the 4s shell DI cross-sections.…”

Working Group 3: Collision Processes

“…At low or moderate densities, ion dynamics play an important role near the center as confirmed by new experimental results (2,3,4) for Lyman and Balmer lines. Computer simulations were employed successfully for investigations of these effects (5)(6)(7)(8). In these computations, electron broadening is accounted for using an impact operator; the ionic contribution is obtained by numerical integration of the atomic Schrodinger equation for a set of ionic mocrofield formed by superposition of Debye-screened fields from uncorrelated particles.…”