1. Auger Electron Spectroscopy of Double and Triple Capture
in Flourine on Argon Collisions
Arifa Habib
J. R. Macdonald Laboratory

2. The Star of this talk, the Tandem Van de
Graaf accelerator

3. The Corona point housing
The Charging belt
The Corona point housing

4. The Scenario....
The 2l2l’2l’’ triply excited states of F9+ had recently been observed in fast energy collisions using the method of triple ion capture to a bare ion using the paracentric HDA [Zamkov. et all, Phys. Rev. A, 67, (050703), 2003]
Since these states are not completely described within the IPM, C.D. Lin et all were working on new ways to describe these states from the correlated motion of the electrons within the state. [Phys.Rev. A, 67, ]

5. The plan
Take advantage of the better resolution of the tandem parallel plate spectrometer designed by H. Aliabadi to find the absolute SDCS and compare the ratios of the following processes:
triple electron capture & double capture in F9+ at different beam energies
double capture of F8+ to triple capture in F9+
Excitation + capture in F8+ to double capture in F9+.

6. The tools....
The electronics set-up
The spectrometer

7. The spectrometer, gas cell and channeltron

8. The reason for using this spectrometer.....
ΔE = Epass * R
E E
Spectrometer resolution found using an electron gun [H. Aliabadi, doctoral thesis, (2004)]

9. And.....results.........(reality kicks in!)

10. What the previous graph means.....
Peak designations:
1: eV, (1s2s2)2S
2: eV, (1s2s2p)4P
3: eV, (1s2s2p)2P_
4: eV, (1s2p2)4P
5: eV, (1s2p2)2D
6: eV, (1s2p2)2S

11. Yes, but what’s it all about ?
Zero degree projectile Auger electron “full spectrum”

12. On to cross section calculation....
DDCSi ≡

13. What was discovered...
at 16 MeV

14. and...the triply excited states!
Triple Capture, 2l2l'2l''
Peak #
LINE
ENERGY
HSCC calc.
Initial
Final
(eV) 8
(2s2p2) 4P
(1s2p)3P
599.5±0.6
599.29
1(a)
(2s2p2) 2D
(1s2s) 1S
609±0.6
609.35
1(b)
(1s2p) 3P
609.74 2
(2s2p2) 2P
(1s2p) 1P
610.5±0.3
611.73 3
(2p3) 2D
612.7±0.4
613.60
4 (a)
(2s2p2) 2S
616.3±0.5
617.08
4 (b)
617.47
5 (a)
618.3±0.3
618.11
5 (b)
(1s2s) 3S
618.39
5 (c)
619.04 6
(1s2p) 3S
625.5±0.3
625.73 7
(2p3) 2P
627.2±0.3
627.12

15. and at 19 MeV..

16. Ratio of double to triple capture...
16MeV
19 MeV
2l2l' to 1s2l2l'
1.41±0.1
1.39±0.1
2l2l' to 2l2l'2l''
6.58±1.0
4.69±0.6

17. and ...

18. The only energy dependence of cross sections calculation so far......
Absolute SDCS measurements of triple electron capture to the C3+ KLL states,
populated in collisions of bare carbon ions with Ar targets.
[Phys. Rev A, 66, (2002)]

19. and more ...

20. Double capture F8+ to Triple capture F9+ = 2.72
and more ratios .....
Double capture F8+ to Triple capture F9+ = 2.72

21. and more ratios .....
F9+ Double capture to F8+ excitation + capture = 5.99
Results of individual lines not plotted yet

22. So for the future....
During last summer and this semester the paracentric spectrometer has been improved
It is hoped that the improvements will allow us to operate with higher decel factors and thus obtain higher energy resolustion.
Its therefore to repeat all of this on the paracentric HDA!
so that
we can further investigate the beam energy dependence of triple to double capture.
Thanks for listening !

23. Just in case someone asks....