Production of Doubly and Triply Excited States by Triple Electron Capture

M. Zamkov, E.P. Benis, P. Richard, T.J.M Zouros,

Triple electron capture in ion-atom collisionsTriple electron capture in ion-atom collisions

Previous experimental studies Previous experimental studies

1. Projectile charge-change 2. Total charge transfer3. Auger spectroscopy in coincidence with

recoil ions4. TOF Triple coincidence of recoil

projectile and target ions with Auger electrons

V< < 1 a.u. - only

Fundamental problem of a many-body dynamic system – test of the most advanced atomic models

Importance in high temperature plasma studies, astrophysics and laser technology

Fundamental problem of a many-body dynamic system – test of the most advanced atomic models

Importance in high temperature plasma studies, astrophysics and laser technology

Bare IONTarget ATOM

Slow

Electron dynamics in slow ion-atom collisionsElectron dynamics in slow ion-atom collisions

V< < 1 a.u.

In slow collisions target electrons molecularize – Extended Overbarrier Model.

Triple electron capture in FAST ion-atom collisionsTriple electron capture in FAST ion-atom collisions

V > u V

u

Collision time is small!

e-e correlations are reduced

V u

Independent Particle Model is expected to reproduce triple electron capture in fast collisions

The captured target electrons see H-like levels of the projectile

Triple electron capture to KLL states in fast C6+ on Ar collisionsTriple electron capture to KLL states in fast C6+ on Ar collisions

C6+ + Ar = C3+(1s2l2l’) + Arq+

Experiment

40 60 80 100 1 20 140 160 180 200 220

220 0

240 0

260 0

280 0

300 0

320 0

340 0

360 0

380 0

400 0

1s2

s2p

2 P+

1s2

s2p

2 P-

1s2

s2p

4 P

1s2

p2 2 D

1s2

s2 2 S

13MeV C6+ + Ar

Channel #

No

rma

lize

d C

ount

s

}{

3

1

8

4

}{ )()()(kj i i

ji

kji

kj bQbPCbPSingle electron transfer probabilities were calculated using the close-coupling method

Independent particle model

ComparisonComparison

5 6 7 8 9 10 11 12 13 140.1

1

10

Model Calculation Experiment

Collision energy (MeV)

DC

S (

10-1

9 cm2 /S

r)

Electron correlation effects do not play a significant role in triple

electron capture athigh collision velocities

Independent particle model gives an adequate representation of

triple electron capture athigh collision velocities v >> 1

M. Zamkov, E.P. Benis, T.J.M Zouros, P. Richard, and T.J. Lee, Phys. Rev. A, 66, 042714 (2002)

Triply excited statesTriply excited states

Fundamental case of an ideal many-body Coulomb system dominated by electron correlation effects

2p2s

1s

hv

Theory

Saddle-point complex-rotationR-matrixDirac-FockTruncated-diagonalizationConfiguration Interaction (CI)

Visualization of triply excited states using a hyperspherical approach

Experiment

Synchrotron radiationAdvanced light source, BerklyPhoton factory, Japan1s22s 2Se 2s22p 2Po

1s22p 2Po2s2p2 2Se, 2Pe, 2De

Population of resonances only in Li atoms theoretical advances in studying triply excited states

for Li-like ions

S=3/2 states cannot be reached due to the dipole selection rules

Limitations of Synchrotron radiation

Population of the triply excited states by triple electron capture !Population of the triply excited states by triple electron capture !

FAST Ion-atom collisions to populate lower intrashells (n=2)

2s22p

2s2p2

2p3

2Po

2Se 2Pe 2De 4Pe

4So 2Po 2Do

F9+Ar

L shell

Ar

Population of all states !

1s2s 1P

1s2s 1S

1s2s 3P

1s2s 3S

IPM - free of e-e correlations

Concentrating on e-e correlations in decay dynamics

570 575 580 585 590 595 600 6050

1

2

8

10

2s2 1S

2s2p 3P

2p2 1D

8

DD

CS

(10

-20 cm

2 / sr

eV)

605 610 615 620 625 6300.0

0.1

0.2

0.3

0.4

0.5

7

6

5 (a,b,c)

4 (a,b)

321 (a,b)

Auger electron energy (eV)

1s2s 1P

1s2s 1S1s2s 3P

1s2s 3S

2s2p2

2p3

2Se 2Pe 2De 4Pe

2Po 2Do

2

1 (a,b)

3

6

4 (a,b)5 a,b,c

7 8

Peak

Present Theory Theory Experiment IPM calc. Present Theory Theory

measurement from Ref [1] from Ref [2] measurement from Ref [1] from Ref [3]

1a 609.38 609.56

1b 609.77 609.77

2 611.9 (0.6) 611.51 611.16 2.9 (0.7) 3.19 0.45 0.39 0.44

3 613.6 (0.6) 613.90 612.34 2.9 (0.8) 1.02 0.32 0.25 0.24

4a 616.97 616.89

4b 617.36 617.10

5a 617.89 618.10 0.55 0.60 0.60

5b 619.1 (0.8) 618.42 618.62 12.7 (2.9) 15.19 0.59 0.56 0.48

5c 619.34 619.28 0.68 0.74 0.75

6 625.4 (0.5) 625.62 625.95 0.5 (0.2) 1.35 0.50 0.37 0.47

7 627.1 (0.5) 627.26 627.39 1.8 (0.4) 1.86 0.78 0.60

8 599.0 (0.7) 599.51 599.09 9.5 (1.9) 13.10 1.00 1.00 1.00

1 U.I. Safronova and R. Bruch, Physica Scripta 57, 519 (1998)

2 M.J. Conneely and L. Lipsky, Atomic Dat. And Nucl. Tables to be published (2002)

3 K.T. Chung, Phys. Rev. A 59, 2065 (1999)

Auger electron energy (eV)

609.4 (0.5)

616.7 (0.5)

SDCS (cm^2)/sr

3.3 (0.6)

0.5 (0.2)

6.05

0.99

Branching ratios

0.41

0.50

0.44

0.50

0.52

0.52

1s2 1S

1s2s 3S

2s2p2 2D

K vacancy production

Resonant TransferExcitation

Determination of Autoionization Rates

Determination of Branching ratios from channels unresolvedIn the other technique

270 275 280 285 290 295 300 305

0

2

4

6

8

10

12

Data R-matrix

1s2s

3 S

2

s2p2

2D

6.58 MeV C4+

[0.9 (1s2 1

S), 0.1 (1s2s 3S)] + H

2

DD

CS

(1

0 -21

cm

2 /eV

sr)

Electron Energy (eV)

188 190 192 194 196 198 200 202 204 206 208 210

0

2

4

6

8

10

12

14

16

18

Data R-matrix

DD

CS

(1

0-21 c

m2 /e

V s

r)

Electron Energy (eV)

1s2s

3 S

2

s2p2

2D

4.0 MeV B3+

[0.75(1s2 1

S), 0.25(1s2s 3S)] + H

2

360 365 370 375 380 385 390 395 400 405

0

1

2

3

4

5

6

7

8

Data R-matrix

1s2s

3 S

2

s2p2

2D

10.14 MeV N5+

[0.75 (1s2 1

S), 0.25 (1s2s 3S)] + H

2

DC

CS

(1

0 -21

cm

2 /eV

sr)

Electron Energy (eV)590 595 600 605 610 615 620 625 630 635 640

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Data R-matrix

Electron Energy (eV)

DD

CS

(1

0 -21

cm

2 /eV

sr)

1s2s

3 S

2

s2p2

2D

20.19 MeV F7+

(1s2s 3S) + H2

R-matrix calculation

ConclusionsConclusions

a) First Experimental measurements of absolute cross sections for triple electron capture resulting from fast collisions of bare C on Ar

b) Extension of the Independent Particle Model (IPM) for the calculation of triple electron capture cross sections.

c) Understanding the role of e-e correlations and projectile screening in triple electron capture resulting from fast ion-atom collisions.

a) Measurements of absolute differential cross sections, resonance energies and Auger decay branching ratios for all autoionizing triply excited states of fluorine with 2s2p2, 2p3 electron configurations.

b) Independent particle model calculations of the differential cross sections for the formation of triply excited states by triple electron capture