X-ray production in heavy-ion—atom collisions:3dσand4fσelectron promotion

Abstract

In this paper, a systematic study of x-ray production in ion-atom collisions is presented for electron promotion by both 3do. and 4fo molecular orbitals. L x-ray production cross sections and highresolution L x-ray spectral measurements are presented for P+, 8+, Cl+, Ar+, and K+ projectiles incident on Ar and CH, gas targets for projectile energies between 15 and 200 keV. Average values of the fluorescence yield and total L-shell ionization cross sections are determined. A dramatic Z dependence observed in the x-ray production cross section is attributed to changes in fluorescence yield.Theoretical calculations of fluorescence yield are found not to agree with experimentally determined values. Finally, inner-shell vacancy production by 3do. electron promotion is found to be much less efficient than 4fa. electron promotion for the co)lision systems studied in this paper.

Specific production of very long-lived core-excited sulfur atoms by 2p−1σ* excitation of the OCS molecule followed by ultrafast dissociation

“…Thus, similar arguments apply to all second-long-period atoms (Al-Ar). Actually, several atomic states with such configurations have been observed: Ar (6−n)+ (2p 5 3p n ) (Fortner 1974), Ar 2+ (2p 5 3p 5 ) (Nordgren et al 1979), S + (2p 5 3p 4 ) ( Ågren et al 1978), Cl (2p 5 3p 5 ns, md) (Caldwell et al 1999). In all these works it was assumed or found that total Auger transition rates of some core-hole states are substantially reduced.…”

Z1oscillations in yields of multicharged ions emitted from a germanium surface when bombarded by light ions

“…A fluorescent yield value of w = 0.0056 was chosen by Kavanagh et al [7,8] so as to match the r p values near the symmetric Z = 29 peak to the geometric size of the L shell of copper. This is a typical tu value [23]. However, when applied to the lower Zi targets of interest here, this value of u predicts rp values which are unphysically small, of the order of the K shell radius.…”

X-ray determination of charge states of ions moving in solids

“…While there are no direct total cross section measurements or theoretical estimates known to us at this time, the argon L-shell x-ray production cross sections in gas target Ar-C collisions have been measured, and an empirical approach used to estimate the total cross .section a. 20 We have used those values in the following calculations. The velocity as a function of distance was found by using the stopping power, both nuclear and electronic; th • tl tabulated ,•n Ref.…”

“…In Ref. 20, the "maximum total cross section, nr 2 for the Ar-C system is estimated. This was used to approximate a two- those shown in Fig.…”