Single-photon emission associated with double electron capture inF9++Ccollisions

Abstract

Radiat ive double electron capture (RDEC), the one-step process occurring in ion-atom collisions, has been investigated for bare fluorine ions collid ing with carbon. RDEC is completed when two target electrons are captured to a bound state of a projectile s imu ltaneously with the emission of a single photon. This work is a follow-up to our earlier measurement of RDEC for bare o xygen projectiles, thus providing a recipient system free of electron-related Coulo mb fields in both cases and allowing for the compar ison between the two collision systems as well as with available theoretical studies. The most significant mechanisms of xray emission that may contribute to the RDEC energy region as background processes are also addressed.

Observation of Radiative Double Electron Capture for Fluorine Ions on Nitrogen and Neon

“…The REC and RDEC energy regions for Ne overlap, therefore creating difficulty in separating x rays from these processes. [9], and are significantly larger than recent theoretical calculations [11]. The F 8+ ions give cross sections that are about four times smaller than for F 9+ .…”

“…The first successful observation of RDEC was performed for 2.38 MeV/u O 8+ + C [8]. This work was continued for 2.21 MeV/u F 9+ projectiles colliding with thin-foil carbon [9]. The first measurements for 2.11 MeV/u F 9+ + N 2 have been reported [10] and are continued here.…”

Observation of radiative double electron capture for

“…The measured differential cross sections and the calculated total cross sections for RDEC for both F 9+ and F 8+ projectiles in the present work are shown in Table II. The RDEC cross sections reported in the previous experiments [11,12] with the carbon target for O 8+…”

“…The cross sections calculated using both methods are shown in Figure 4 The two solid squares show the measured cross sections for O 8+ and F 9+ incident on the carbon foil target in experiments [11] and [12], while the open squares show the upper bound of the cross sections determined from experiments [9] and [10] for Ar 18+ and U 92+ projectiles, respectively. The total RDEC cross sections obtained in the current experiment, for both Previous experiment [11,12] Upper limit (experiment) [9,10] Present results…”

“…RDEC can be used to cleanly study electron correlation if the electrons are captured to a bare projectile ion, since the two captured ions are not influenced by the neighboring electrons. RDEC has been studied experimentally [9][10][11][12][13] and theoretically [14][15][16][17][18][19][20] for more than two decades, and the first successful measurement [11] was reported in 2010 for 2.38 MeV/u O 8+ ions colliding with a thin foil carbon target. Both the REC and RDEC processes are illustrated in Figure 1.…”