Collisional X-Ray Excitation in Solid and Gaseous Targets by Heavy-Ion Bombardment

Abstract

Large differences have been found in the x-ray yields produced by 22.5-and 48-MeV iodine ions incident on solid ( 34 Se) and gaseous ^Br and 3 6 Kr) targets. These differences are attributable to the steady-state excitation of the penetrating ion prior to the vacancy producing collision, and yield information on the state of energetic ions in solids.

Effects of multiple ionization and intrashell coupling inL-subshell ionization by heavy ions

“…For solid targets of our experiment, this finding may not hold since combined effects of multiple scattering and dynamical screening in ion-solid collisions enhance the population of 2p states [30]. Discussing differences in x-ray production in solid and gaseous targets by heavy ions, Lutz et al [31] noted that in a solid all vacancies above the M shell are probably filled. This would make the production of an x-ray more likely than of an Auger electron.…”

“…(6) and (7) smaller ionization cross sections for the L 1 subshell. Yet, Lutz et al [31] also argued that the milieu of high electron density in a solid may tend to enhance decay via less selective nonradiative transitions and, thus, cause an effective suppression of the fluorescence yield. The contradictory and uncertain outcome of such arguments for deexcitation of ionized atoms in solids is not much less certain in analysis of electron cascades in free atoms where the results are obscured by uncertain contributions of different subshells and the lack of the self consistency in the selected database for x-ray, nonradiative, and electron shake-off rates [29].…”

Electronic States of Ions Recoiling into Vacuum and Gases

“…Here I will just two. The first involves x-ray production in solid and gas targets with iodine ions in Se, Br, and Kr targets [15]. These are adjacent elements the periodic table and the principal difference is that Se is a solid wh it and Lichten {14] have shown that it is really quite simple to predict th electrons will be ionized in a collision involving two dissimilar atoms.…”

“…The first involves x-ray production in solid and gas targets with 22-48 MeV > ions in Se, Br_ and Kr targets [15]. These are adjacent elements in periodic table and the principal difference is that Se is a solid while Br Kr are gases.…”

Charge-state distributions and the population of x-ray emitting states

“…The authors claim that a shift of the projectile binding energies due to a different number of outer-shell vacancies in both cases is responsible for changes in the diabetic molecular correlation scheme and different coupling mechanisms in consequence. Lutz et al [7] compared the L-x-ray yield of solid selenium targets with that of gaseous targets of bromine and krypton when bombarded with 22.5 MeV and 48 MeV iodine ions. The authors conclude that in the solid target the iodine M-shell is depleted, whereas in the gaseous targets deexcitation of the iodine M-shell between two successive collisions may occur.…”