Ph. D. Defense Committee:

Chair: J. H. Edgar Advisor: B. D. DePaola Member: C. L. Cocke Member: C. D. Lin Member: P. M. A. Sherwood

Presenter: Hai T. Nguyen

MOTRIMS: Magneto-Optical Trap Recoil Ion Momentum Spectroscopy

Hai Nguyen, Richard Brédy, Xavier Fléchard,

Alina Gearba, How Camp, Takaaki Awata,

Johnathan Sabah, Kyle Wilson, and Brett DePaola.

TrappingLASERS

Ion Beam

Recoil Ion2D-PSD

Projectile2D-PSD

Deflector plates

Anti-HelmholtzCoilsFaraday cup

x

y

z

Spectrometer

TrappingLASERS

Ion Beam

Recoil Ion2D-PSD

Projectile2D-PSD

Deflector plates

Anti-HelmholtzCoilsFaraday cup

x

y

z

Spectrometer

OUTLINE

Reviews of Cold Target Recoil Ion Momentum Spectroscopy

Motivation

Experimental Setup

Results

Conclusion and Outlook

COLTRIMS: Principles

Cold Target Recoil Ion Momentum Spectroscopy is a technique in which information about the collision is obtained through the measurement of the momentum transferred to the ionized target (atom/molecule).

ppP’

pr

p

r ||

Q: energy defect: Scattering angle (Lab frame)Prll , Pr : parallel and perpendicular recoil momentum componentsPP , PP’ : projectile momentum before and after the collisionVp: projectile velocitync: number of transferred electrons

2

2

||Pc

rP

vnPvQ

For charge transfer:

P

r

P

P

P

pr ┴

COLTRIMS: Pros & Cons

Pros: This technique allows kinematically complete experiments.

The good resolution in the measured longitudinal recoil ion momentum allows accurate determination of the inelasticity in the collision and therefore identification of the different collision channels by their different Q-values.

Cons: Ultimately, in COLTRIMS, the resolution is limited by the

temperature of the target (>100 mK) traditionally delivered by a supersonic jet.

Problematic for collisions with excited target.

MOTIVATION

Collisions with excited target (~ 20%).

Resolution is no longer limited by target temperatures (~ 130K).

Cross-section measurements provide rigorous test for theory.

EXPERIMENTAL SETUP

EXPERIMENTAL RESULTS

Results Obtained: Energy dependent Cs+ + Rb (5l), l = s and p Energy dependent Na+ + Rb (5 l), l = s and p MOTRIMS probes MOT excited state fractions Systems with energetically degenerate channels (Dual beam method)

Li+ + Rb K+ + Rb

Rb+ + Rb

Results will be shown for: 7 keV Na+ + Rb (5l), l = s and p Na+ + Rb (5l) compare with theory MOT excited state populations Rb+ + Rb(5l), l = s and p

RESULTS7 keV Na+ + Rb (5l), l = s and p

-5

-4

-3

-2

-1

0

4d 2D5/2

, 4d2D3/2

4f 2F7/2

, 4f2F5/2

5s 2S1/2

4p 2P1/2

, 4p 2P3/2

23Na

4s 2S1/2

3d 2D5/2

, 3d2D3/2

3p 2P1/2

, 3p 2P3/2

3s 2S1/2

12f

4d 2D3/2,5/2

5p 2P3/2

5s 2S1/2

87Rb

Pote

ntia

l Ene

rgy

(eV)

-3 -2 -1 0 1 2 30

2000

4000

6000

8000

10000

12000

14000

16000

Coun

ts

Q value (eV)

5p-3p5s-3p

5s-3s5p-4s

RESULTS7 keV Na+ + Rb (5l), l = s and p

-3 -2 -1 0 1 2 30

5

10

15

20

Q Value (eV)

TAC

Tim

e (

s)

5.000

6.776

9.183

12.44

16.86

22.85

30.97

41.97

56.88

77.09

104.5

141.6

191.9

260.0

Laser off

-3 -2 -1 0 1 2 30

5000

10000

15000-3 -2 -1 0 1 2 3

0

1000

2000

3000

4000

5000

5p-3p

5s-3s

5s-3p

Q Value (eV)

Laser On

5s-3s

5s-3p

Co

un

ts

Laser Off

MOTRIMS as a probe 7 keV Na+ + Rb (5l), l = s and p

-3 -2 -1 0 1 2 30

2000

4000

6000

8000

10000

12000

14000

16000

4p*

3d*

4d*

5s*

3d

4s*

3p

3p*

3s

Coun

ts

Q value (eV)

TT

AA

on

off

off

ss

on

ssf 1

s

p

s

p

A

A

f1

1

RESULTS7 keV Na+ + Rb (5l), l = s and p

Rb(5s) to final state

Relative cross sections (5s)

3s 0.19 ± 0.01

3p 0.78 ± 0.01

3d 0.03 ± 0.01

Rb (5p) to final state

Relative cross sections (5p)

3p 0.78 ± 0.02

4s 0.07 ± 0.01

3d 0.11 ± 0.02

4p 0.03 ± 0.01

5s 0.00 ± 0.01

4d 0.01 ± 0.01

7 keV Relative cross sections

p/s2.75 ± 0.01

RESULTS7 keV Na+ + Rb (5l), l = s and p

-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.00.0000

0.0005

0.0010

0.0015

0.0020 Matrix1

5s-3d

7 keV Na++Rb(5s),Rb(5p) Na*+Rb+

5s-3p

5p-4d

5p-4s

5p-3p

5s-3s

2.000

3.431

5.886

10.10

17.32

29.72

50.99

87.48

150.1

257.5

441.7

757.8

1300

Q value (eV)

Sca

tterin

g A

ngle

(ra

d)

RESULTS7 keV Na+ + Rb (5l), l = s and p

Compared to calculation

0.0 0.5 1.00

2

4

6

8

0

2

4

6

8

10

Sin X

DC

S (1

0-1

3 c

m2 )

Laboratory Angle (mrad)

5s-3s

5s-3p

0.0 0.5 1.00

2

4

6

0

2

4

6

8

Laboratory Angle (mrad)

Sin X

DC

S (1

0-1

3 c

m2 )

5p-4s

5p-3p

ENERGY-DEPENDENT RESULTSCompared to calculation

1 2 3 4 5 6 7 81

10

100

Collision Energy (keV)

1 2 3 4 5 6 7 81

10

100

Collision Energy (keV)

ss

ps

35

35

sp

pp

45

35

ENERGY-DEPENDENT RESULTS

Compared to calculation

0.0 0.5 1.0 1.5 2.00

2

4

6

8

10

12

14

sin x

DC

S (1

0-1

1cm

2 )

0.0 0.5 1.0 1.5 2.00

2

4

6

85P - 3P

E = 2 keVE = 5 keVE = 7 keV

E (mrad)

Expt

. DC

S (1

0-1

1cm

2 )

0 1 2 3 4 50

2

4

6

8

10

12

sin x

DC

S (1

0-1

3cm

2 )

E (mrad)

0 1 2 3 4 50

2

4

6

8

10

E = 5 keV

E = 2 keV

E = 7 keV

5S - 3P

Expt

. DC

S (1

0-1

3cm

2 )

(keV mrad) (keV mrad)

5p-3p 5s-3p

MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

-3 -2 -1 0 1 2 30

5

10

15

20

Q Value (eV)

TAC

Tim

e (

s)

5.000

6.776

9.183

12.44

16.86

22.85

30.97

41.97

56.88

77.09

104.5

141.6

191.9

260.0

-3 -2 -1 0 1 2 30

5000

10000

15000-3 -2 -1 0 1 2 3

0

1000

2000

3000

4000

5000

5p-3p

5s-3s

5s-3p

Q Value (eV)

Laser On

5s-3s

5s-3p

Co

un

ts

Laser Off

MOTRIMS as a probe 7 keV Na+ + Rb (5l), l = s and p

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.400

1

2

3

4

5

P /

S

Excited State Fraction

P /

S

Average P /

S

-3 -2 -1 0 1 2 30

2000

4000

6000

8000

10000

12000

14000

16000

4p*

3d*

4d*

5s*

3d

4s*

3p

3p*

3s

Coun

ts

Q value (eV)

MOTRIMS as a probe 7 keV Na+ + Rb (5l), l = s and p

-3 -2 -1 0 1 2 30

2000

4000

6000

8000

10000

12000

14000

16000

4p

*3

d*

4d

*5

s*

3d

4s*

3p

3p

*

3s

Cou

nts

Q value (eV)

TT

AA

on

off

off

ss

on

ssf 1

ppss

pp

ARA

Af

08.026.10 ss

ppR

MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

0 1 2 3 4 50.0

0.2

0.4

0.6

0.8

1.0

Re

lativ

e P

op

ula

tion

Time (ms)

Spopulation Ppopulation

5s

5p

1

2

10

23

Other Collision System: Difficulty

-5

-4

-3

-2

-1

012f

4d 2D3/2,5/2

5p 2P3/2

5s 2S1/2

12f

87Rb

4d 2D3/2,5/2

5p 2P3/2

5s 2S1/2

Po

ten

tial E

ne

rgy

(eV

)

-3 -2 -1 0 1 2 30

5

10

15

20

Q value (eV)

TAC

time (

s)

4.0005.7808.35212.0717.4425.2036.4152.6176.03109.9158.7229.4331.4478.9692.01000

RESULTS7 keV Rb+ + Rb (5l), l = s and p

-3 -2 -1 0 1 2 3

200

400

600

800

1000

5p-4d5s-5p 5p-5s5s-5s5p-5p

Q value (eV)

Scat

terin

g An

gles

(r

ad)

2.000

4.536

10.29

23.33

52.92

120.0

272.2

617.3

1400

5s-5p/5p-5s = 2.95 ± 0.05

RESULTS7 keV Rb+ + Rb (5l), l = s and p

0 200 400 6000

500

1000

1500

2000

25000 200 400 600

0

400

800

1200

1600

Scattering Angles (rad)

7 keV Rb+ + Rb 5p-5p

Coun

ts

7 keV Rb+ + Rb 5s-5s

0 200 400 600 800 10000

20

40

60

80

100

0 200 400 600 800 10000

20

40

60

80

7 keV Rb+ + Rb 5s-5p

Scattering Angles (rad)

Coun

ts

7 keV Rb+ + Rb 5p-4d

RESULTS7 keV Rb+ + Rb (5l), l = s and p

0 5 10 15 20 25 30 35 40 45 50-0.20

-0.15

-0.10

-0.05

0.00

0.05

Rb(4d)

Rb(5p)

Rb(5s)

Rb

2

+

U(R

) (a

.u)

Internuclear Separation R (a.u)

5s-5p/5p-5s = 2.95 ± 0.05

DCS for resonant channels are more forwardly peaked

5s-5s Oscillatory Structure5p-5p No Oscillatory Structure

SUMMARY

‘Simultaneous’ measurements of excited state fraction and relative cross sections.

Kinematically complete collisions study for alkali ion – trapped atoms including energetically degenerate systems.

MOTRIMS is a powerful tool for ion-atom collisions.

Using MOTRIMS as a probe at MOT dynamics under some perturbation.

THANKS

Committee Members MOTRIMS Group JRML Support Staff:

Kevin Carnes, Scott Chainey, Charles Fehrenbach, Bob Geering, Bob Krause, Vince Needham, Al Rankin, Carol Regehr, and Mike Wells.

Questions & Answers

Cooling and Trapping Optics Layouts Experimental Setup Analysis Excited State Formula? Others Systems

SIMPLE OPTICS LAYOUT

TRAP

REPUMP

Sat abs

Sat abs

F=40cmAOM 80MHz Com

TRAPPING OPTICS

Blocker

F=40cm

O I/2

O I

/2

DAVLL

DAVLL

Q&A

SIMPLE OPTICS LAYOUT

PBS

PBS

/2

/2

/4

/4

/4

/4

/4

/4

MirrorM

irror

Mirror

Mirror

Mir

ror

Mirror

From AOM

Q&A

TRAPPING OPTICS

Projected TOF

0 20 40 60 80 100 120 1404.5x10-5

5.0x10-5

5.5x10-5

6.0x10-5

6.5x10-5

7.0x10-5

7.5x10-5

8.0x10-5

8.5x10-5

9.0x10-5

Cs133

Rb85

K39

Na23

Li6

TO

F s

Mass a.u.

2 KeV 5 KeV 7 KeV

6 8.268E-5 8.548E-5 8.623E-523 7.538E-5 8.086E-5 8.232E-539 7.087E-5 7.801E-5 7.991E-585 6.162E-5 7.216E-5 7.497E-5133 5.442E-5 6.761E-5 7.112E-5

--

Mass a.u. 2 keV s 5 keV s 7 keV s

Q&A

RESULTS7 keV Na+ + Rb (5s, 5p)

offonp

onss

offs TnnA )(

ons

onp

onp

ons

s

p

A

A

n

n

ononss

ons TnA off islaser when Time T

on islaser when Time T

off islaser when s from capture of Amplitude A

on islaser when s from capture of Amplitude A

on islaser when state iin atoms ofnumber n

off

on

offs

ons

th

i

on

off

offs

ons

ons

onp

onp

T

T

A

A

nn

nf 1

ononpp

onp TnA

ss

pp

ss

pp

off

totalofftotal A

A

T

TQQ

Independent of excited state measurements:

Q&A

0 5 10 15 20 25 30 35 40-0.25

-0.20

-0.15

-0.10

-0.05

0.00

Na 4s

Rb 5pNa 3p

Rb 5s

Na 3s

NaRb+

Ene

rgy

(a.u

.)

Internuclear Separation R (a.u.)

LASER

m = +1

m = 0

m = -1

j= 0

j=1

m = +1 m = -1

+ -

Optical frequency

z

Ftot

F-

F+

Fz fo

rce

com

pone

nt

Vzvelocity component

z

+ -BRb

VZ

Cooling and Trapping

Q&A

5s

5p

12

1023

RESULTS7 keV Li+ + Rb (5l), l = s and p

-6

-5

-4

-3

-2

-1

012f

4d 2D3/2,5/2

5p 2P3/2

5s 2S1/2

3p 2P1/2

, 3p 2P3/2

3d 2D5/2

, 3d2D3/2

3s 2S1/2

2p 2P1/2

, 2p 2P3/2

2s 2S1/2

7Li87Rb

Pote

nti

al

Energ

y (

eV

)

Q&A

RESULTS7 keV Li+ + Rb (5l), l = s and p

-3 -2 -1 0 1 2 30

5

10

15

20

Q Value (eV)

Tim

e (s

)

1.000

1.886

3.557

6.707

12.65

23.85

44.99

84.84

160.0

-3 -2 -1 0 1 2 30

3000

6000

9000

5s-3s

5p-3p

5s-2p 5p-3s

5p-2p

5s-2s

Coun

ts

Q Value (eV)

total

7 keV Li+ + Rb

Q&A

Multi-Projectile Source

0 1000 2000 3000 4000 5000 6000 7000

100

1000

10000

7Li+ + Rb

6Li+ + Rb

23Na+ + Rb

Cou

nts

TOF (channels)

Total TOF Spectrum

Q&A

Probe: 7 keV Na+ + Rb (5l)

-3 -2 -1 0 1 2 30

50

100

150

200

250

300

5s-3p

5p-4s

5p-3p

5s-3s

Coun

ts

Q Value (eV)

Total

Na+ Contaminant in Li+ source

p

son

off

offs

onp

offs

onp

ons

onp

onp

T

T

A

A

n

n

nn

nf

04.019.0 f

Known

Q&A

7 keV Li+ + Rb (5l)

-3 -2 -1 0 1 2 30

3000

6000

9000

5s-3s

5p-3p

5s-2p 5p-3s

5p-2p

5s-2s

Coun

ts

Q Value (eV)

total

7 keV Li+ + Rb

p

son

off

offs

onp

offs

onp

ons

onp

onp

T

T

A

A

n

n

nn

nf

Known Results

Q&A

Cross Sections 7 keV Li+ + Rb

35.048.3 s

p

023.0828.025

s

ps

091.0125.035

p

pp

Waiting for TC-AOCC results

076.0172.025

s

ss

022.0658.035

p

sp

045.0217.025

p

pp

Q&A

7 keV Li+ + Rb Scattering Angle Information

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000

8000

Coun

ts

Scattering Angle (rad)

5p-3p, 5s-2p, 5p-3s

-3 -2 -1 0 1 2 30

500

1000

1500

2000

5s-2s

5p-2p

5p-3s5s-2p5p-3p

Q Value (eV)

Scatt

erin

g An

gle (

rad)

1.000

2.400

5.759

13.82

33.17

79.59

191.0

458.4

1100

Q&A

7 keV Li+ + Rb Scattering Angle Information

0 200 400 600 800 10000

500

1000

1500

2000

2500

Coun

ts

Scattering Angle (rad)

5p-2p, 5s-2s

Grouped scattering angle information are hard to extrapolate (Rb + Rb).

Theoretical Comparison not trustworthy.

Using a weighted method to deduce individual channel scattering angle information.

Q&A

7 keV Li+ + Rb Scattering Angle Information

-3 -2 -1 0 1 2 30

500

1000

1500

2000

5p-3p 5s-2s5p-2p

5p-3s5s-2p

Q Value (eV)

Scatt

erin

g An

gle(

rad)

1.000

2.306

5.318

12.26

28.28

65.23

150.4

346.9

800.0

-3 -2 -1 0 1 2 30

500

1000

1500

2000

5s-2s

5s-2p

Q Value (eV)

Scatt

erin

g An

gle(

rad)

1.000

2.080

4.325

8.996

18.71

38.91

80.92

168.3

350.0

Laser on Laser off

Q&A

7 keV Li+ + Rb Scattering Angle Information

0 200 400 600 800 10000

200

400

600

800

1000

Co

unts

Scattering Angle (rad)

NssON

0 200 400 600 800 10000

500

1000

1500

2000

2500

3000

Coun

ts

Scattering Angle (rad)

NppON

Q&A

RESULTS6 keV Cs+ + Rb (5l), l = s and p

-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5

0.0005

0.0010

6 keV Cs++Rb(5s),Rb(5p) Cs*+Rb+

5p-5d

5s-6p

5s-6s

5p-6p

5p-6s

2.000

2.908

4.229

6.151

8.944

13.01

18.91

27.51

40.00

58.17

84.59

123.0

178.9

260.1

378.3

550.1

800.0

Q value (eV)

Sca

tterin

g A

ngle

(ra

d)

Q&A

RESULTS6 keV Cs+ + Rb (5l), l = s and p

0 200 400 600 800 10000

50

100

150

200

0

5

10

15

Rb(5p) to Cs(6p)

Scattering Angle rad

d/d

10-1

2 cm2 /r

ad

Rb(5s) to Cs(6s)

Q&A

SINGLE CAPTURE IN 6 keV Cs+ + Rb (5l), l = s and p

Recoil ion PSD image

50 100 1 50 200 250

50

100

150

200

250

Recoil PSD spectrum for charge transfert from Rb(5s) to Cs(6s)

Recoil X position (channels)

Rec

oil Y

pos

ition

(ch

ann

els)

1.000

1.994

3.976

7.929

15.81

31.53

62.87

125.4

250.0

50 100 1 50 200 250

50

100

150

200

250

Recoil PSD spectrum for charge transfert from Rb(5s) to Cs(6s)

Recoil X position (channels)

Rec

oil Y

pos

ition

(ch

ann

els)

1.000

1.994

3.976

7.929

15.81

31.53

62.87

125.4

250.0

Q&A

RESULTSEnergy dependent Cs+ + Rb (5l), l = s and p

Q&A

Excited State Fraction Formula?

20

0

421

s

sf

DetuningLaserStateExcitedofLinewidth

saturation

total

I

Is 0

33

2 chI saturation

SystemofRateEmissionneousSponta

Q&A

So, What’s the Problem!?So, What’s the Problem!?

52P3/2

52S1/2

Specific Example: 87Rb

F=1

F=2

F=1

F=2

F=0

Trapping Laser

F=3 -3 -2 -1 0 +1 +2 +3

-2 -1 0 +1 +2

MF Levels!MF Levels!

15 6 3

95

10

8 8

1

5

Q&A

So, What’s the Problem!?So, What’s the Problem!?

Beam Symmetry?

I1 = 0.50 mW / cm2

I2 = 0.45 mW / cm2

Here’s the problem!Here’s the problem!

33

2 chI saturation

B-Field Gradient?

Q&A

Preliminary ResultsPreliminary Results

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80.00

0.05

0.10

0.15

0.20

0.25

0.300.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

0

2

4

6

8

10

12

14

Data Fit: s

0 = 0.68

Exc

ited

-Sta

te F

ract

ion

Detuning (-)

Co

un

t Ra

te (

cps)

Count Rate

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80.00

0.05

0.10

0.15

0.20

0.25

0.300.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

0

2

4

6

8

10

12

14

Data Fit: s

0 = 0.68

Exc

ited

-Sta

te F

ract

ion

Detuning (-)

Co

un

t Ra

te (

cps)

Q&A