4th annual LEIF meeting - Belfast June 29, 2003

1

IsoelectronicIsoelectronic study ofstudy of triply- excited triply- excited Li-like Li-like electron scattering resonanceselectron scattering resonances

Theo J.M. ZourosTheo J.M. ZourosUniversity of Crete/FORTH – HeraklionUniversity of Crete/FORTH – Heraklion

GREECEGREECE

Recent collaboratorsRecent collaborators

Dr. Manolis Benis PhD 2001

Univ. of Crete & JRM

Prof. Tom GorczycaWestern Michigan Univ.

R-matrix calculations

J.R. Macdonald LabKansas State Univ.

Prof. Pat Richard

Mikhail Zamkov Grad Student

Production of triply-excited Li-like statesProduction of triply-excited Li-like states

Lithium

1s2 1Se

RResonantEElectronSScattering

Foil excitation

1s22s 2Se

2s22p 2Po

2s2p2 2De, 2Se, 2Pe

2p3 2So

1s22p 2Po

671 nm cw dye laser

ALS synchrotron – Γ=39meV1s2p 3,1Po

1s2s 3Se1s2s 1Se

PhotoionizationPhotoionization: γ + 1s22p 2P0 1s2l 3,1L + e-(εℓ)

RESRES: e- + 1s2s 3Se 2s2p2 2De

1s2l 3,1L + e-(εℓ)

Cubaynes et al PRL 1996

2Pe

-like

He-like ionsZ=5-9

Electron - ion collisions: Electron - ion collisions: Production and decay of Production and decay of

doubly excited statesdoubly excited states

capture of a (quasi-) free electron + excitation inverse autoionization

radiative stabilizationrecombinationDR or RTEX

autoionizationResonant electron

scatteringRES or RTEA

EEee

(quasi-)free (quasi-)free electronelectron

EE11-E-E00

EE11

EE00

EEnn

BBnn

EEe e + B+ Bn n = E= E11-E-E00

fi Eqqq

E enAASAe )l1s()2s2p()1s2s ( 2)1(3

EE11

EE00

EEnn

AAq+q+

EE11

EE00

EEnn

h

AAq-1+q-1+

AAq+q+

EE11

EE00

EEnn

doubly-excitedintermediate state

RTE

AAq-1+q-1+

UoC HEMISPHERICAL ANALYZER UoC HEMISPHERICAL ANALYZER WITH 2-D PSD 0WITH 2-D PSD 0oo ELECTRON SPECTROMETER ELECTRON SPECTROMETER

UoC HEMISPHERICAL ANALYZER UoC HEMISPHERICAL ANALYZER WITH 2-D PSD 0WITH 2-D PSD 0oo ELECTRON SPECTROMETER ELECTRON SPECTROMETER

Ion Beam

Gas in Pressure Gauge

Gas Cell

PSDX-PositionY- Position

Timing

4-element lens

Faraday Cup

Inner hemisphere

electrons

Outerhemisphere

θ e-

IonResolution ~ 0.1%ΔΩ = 1.8 x 10-4 sr

00 dgrs

Elastic scattering of quasi-free electrons on BElastic scattering of quasi-free electrons on B3+3+ ions ions

0

2

4

6

8

10

12

(2s2

p2 ) 2 D

(2s2

p2 ) 2 D

3.80 MeV B3+(1s2) + H2

4.11 MeV B3+(1s2, 1s2s) + H2

DD

CS

(x

10 -

21 c

m2 /e

V s

r)

180 185 190 195 200 205 210

0

2

4

6

8

10

Auger Electron Energy (eV)

E.P. Benis et al, in XXI ICPEAC, Sendai, Japan, p. 505 (1999)

1 2 3 4 5 6 7 80

1

2

3

4

Data IA - RTEA

(x 0.61)

SD

CS

(1

0-20 c

m2 /s

r)

Projectile Kinetic Energy (MeV)

M. Zamkov et al. Phys. Rev A 65, 032705 (2002)

Triply Excited States !2s2p2 2D

1s2p 3P

1s2s 3SRTEA

0

50

100

150

200

250

300

0

25

50

75

100

125

150

175

-650

-600

-550

-500

-450

-400

-350

-300

-250

-200

-150

-100

1s3l1snl

RES

2l2l'nl"2l3l'nl"

1s2lnl'

RES

B2+ B3+ B4+

(1s2)1S

(2s22p)2P

(1s2s)1S(1s2p)3P(1s2p)1P

2l2l'

(2s2p2)2D

2l3l'

(1s22p)2P

1s

(1s22s)2S

(1s2s)3S

Energy Level diagram of boron

Bin

din

g E

ne

rgy

(eV

)

11

2 e

V

H2

Ee-=

18

4 e

VE

e-=

18

4 e

V

Au

ge

r e

lect

ron

en

erg

y (e

V)

Resonant electron scattering R-matrix calculationResonant electron scattering R-matrix calculation

270 275 280 285 290 295 300

0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

f3S=12%

g

fe

dc

b

a

Electron Energy (eV)

d2 /dd

E (

10-2

1 cm2 /e

V s

r)

6.58 MeV C4+

0.1

1

10j

ihgfe

dc

b

a

e- + C4+(1s2 1S)

d/d

(10-1

8 cm2 /s

r)

0

1

2

3

4

5

3P

1S

3S e- + C4+(1s2s 3S)

jih

First Z-dependence study of a triply-excited stateFirst Z-dependence study of a triply-excited state

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

0

2

4

6

8

10

12

14

f3S=25%

g

f

e

d

2s2p

1 P

4.00 MeV B3+

370 375 380 385 390 395 400 405

0

1

2

3

4

5

f3S=25%

e

dc

b

a

10.14 MeV N5+

475 480 485 490 495 500 505 510 515

0.0

0.5

1.0

1.5 f3S=25%

c

b

a

14.35 MeV O6+

590 595 600 605 610 615 620 625 630 635 640

0.0

0.2

0.4

0.6

f3S=25%

20.18 MeV F7+

Benis et al. submitted PRL June 2003

Summary and ConclusionSummary and Conclusion

• Isoelectronic investigationIsoelectronic investigation of the scattering properties of of the scattering properties of the triply-excited the triply-excited 2s2p2s2p22 22DD state for He-like state for He-like B, C, N, O, FB, C, N, O, F in collisions with Hin collisions with H22

• Resonant electron scattering Resonant electron scattering R-matrixR-matrix calculations within calculations within the electron scattering model (impulse approximation) the electron scattering model (impulse approximation) found to be in good agreement with experiment found to be in good agreement with experiment • Scattering techniquesScattering techniques still the only way to obtain still the only way to obtain information about information about resonances for HCI with Z>3resonances for HCI with Z>3 - - Free electron laserFree electron laser is expected to change this is expected to change this but still need about 10 years?!but still need about 10 years?!