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56

RIKEN Accel. Próg. Rep. 24 (1990)

111-2-22. Electron Spectra from Doubly Excited Boroń lons

Produced by Double Electron Capture

H.A. Sakaue, Y. Kanai, T. Nabeshima, N. Nakamura, I. Yamada,* S. Ohtani, K. Wakiya, H. Suzuki, T. Takayanagi, T. Kambara,

A. Danjo, M. Yoshino, and Y. Awaya

224    226    228    230    232    234

Fig. 2. High resolution ejected electron spectra from the 2/3/' configuration of B³⁺. Each peak is tentatively identified as shown. Collision energy is (a) 65 keV; (b) 50 keV; and (c) 37.5 keV.

We measured spectra of electrons ejected by the following double-electron transfer collisions at varying collision energies (37.5, 50, and 65 keV);

B⁵+ + He(ls²) —>B³⁺(2/n/') ^lL + He²*

UB⁴⁺(ls)+e“.

ⁿB⁵⁺ ions were produced with the ECRIS (Electron Cyclotron Resonance łon Source) construct-ed as an ion source for the RIKEN AVF cyclotron. Spectra of ejected electrons were measured by zero-degree electron spectroscopyT

ELECTRON ENERGY (eV)

Fig. 1. High resolution ejected electron spectra from the 2121' configuration of B³⁺. Each peak is tentatively identified as shown. Collision energy is (a) 65 keV; (b) 50 keV; and (c) 37.5 keV.

High resolution spectra of ejected electrons from 2/2/' and 2/3/' States are shown in Figs. 1 and 2, respectively. We tentatively identify each peak as denoted in the figures. The relative-intensity ratio of the peaks in 2/2/' does not change with collision energy, but that of the

ELECTRON ENERGY (eV)

peaks in 2/3/' changes. Possible explanations for this phenomena are (1) the position of the reac-tion window changes with collision energy and (2) the magnetic sublevel distribution mi of each angular momentum State (L) produced by double electron capture changes with collision energy.^l)

Since the observed electron peaks are shifted by a post collision interaction (PCI) effect, so we cannot directly compare the observed peak energies with theoretical values. Precise analysis is in progress.

References

1) H.A. Sakaue, Y. Kanai, Y. Ohta, K. Kushima, M. Inaba, S. Ohtani, K. Wakiya, H. Suzuki, T. Takayanagi, T. Kambara, A. Danjo, M. Yoshino, and Y. Awaya: J. Phys., B23, L401 (1990).

*

National Institute for Fusion Science.