1

S.N. Jha, D. Bhattacharyya, A.K. Poswal, and S.C. SabharwalRaja Ramanna Centre For Advanced Technology, Indore, India

snjha@rrcat.gov.in

First Results from a Dispersive EXAFS beamline at Indus-2 SR facility

2-5 February, 2009, ESRF

2

3

Outline

• Introduction to Indus SR• Beamline description

– Basic working principle

– Optical layout– Design procedure

– Mechanical Layout– Experimental station

• Commissioning results

4

Schematic view of Indus complex

5

Indus-2 synchrotron spectrum

100

101

102

103

104

105

1011

1012

1013

(b)

(a)

Beam Energy : 2.5 GeVa: Bending Magnetb: Wave Length ShifterP

hoto

n F

lux

Photon Energy (eV)

Indus-2 Parameter

Energy : 2.5 GeVCurrent : 300mAField : 1.5 T (BM)Circumference:172.5mLifetime: 15 Hrsλ c =1.98 Å (6.23 KeV)

Beam size

σx : 0.234mmσy : 0.237 mm

RF frequency :505.812 MHz

6

Status of Indus-2

Indus-2 operation at 2.5GeV

0

10

20

30

40

50

60

11:1

9:2

7

11:5

2:4

8

12:2

6:1

1

12:5

9:3

3

13:3

2:5

7

14:0

6:2

3

14:3

9:4

5

15:1

3:0

5

15:4

6:2

5

16:1

9:4

5

16:5

3:0

5

Time [Hrs]

Be

am

Cu

rre

nt

[mA

]

0

500

1000

1500

2000

2500

3000

Be

am

En

erg

y [

Me

V]

Beam Current Beam Energy

7

Beamline Layout view of Indus-2

SAXS/WAXS B

EAM LIN

E

IMAGING BEAM LINE

BL-1

BL-2

BL-4

BL-3SE PTUM

XR

F M

ICR

OP

RO

BE

BE

AM

LIN

E

GIS

BE

AM

LIN

E

BL-18

PE

S B

EA

MLI

NE

BL-12

ED-EXAFS BEAM LINE

SCAN

NING

-EXAFS BEAMLIN

E

X-RAY LITHOGRAPHY BEAM LINE

BL-5

BL-6

BL-7

BL-9

BE

AM

LIN

E C

ON

TRO

L P

AN

EL A

REA

BL-8

ED

XR

D B

EA

MLIN

EX

RD

-BE

AM

LINE

BL-10

BL-11

BL-14

BL-13

BL-15BL-17

BL-16 MC

D B

EA

MLI

NE

TRANSPORT LINE-3

PROTEIN CRYSTALLOGRAPHY BEAMLINE

BL-25

BL-26

BL-27

BL-20

BL-19

BL-21

BL-22

BL-24

BL-23

♣

♣

♣BL Under construction

♣♣ ♣

♣02:MI

04:PRC

07:XRL

13:GIS

09:EXAFS-scanning 14:PES

16:XRFµµµµ

18:SAXS

♣

♣

37 BLs

8

Characteristics of ED XAFS BL at Indus-2

• Source: Bending magnet

• Energy range: 5-20keV

• Resolution: 10-4

• Band pass: 300ev to 2000eV

• Flux: 1012 photons/sec/1000eV

• Polychromator: Si(111)

• Detector: CCD(2k x 2k ; pixel: 13.5µ)

9

a

c

b

θo

Principle of Action:

•Synchrotron Radiation is diffracted and focused on sample by a perfect crystal, bent elliptically such that the sample and the source are at focii of the ellipse. Transmitted intensity is detected by a position sensitive CCD detector.

Energy (eV)

θθθθo(deg)

a (mm)

b (mm)

c (mm)

5,000 23.28 10285 1335.5 10198

10,000 11.40 10320 708.1 10296

20,000 5.67 10702 524 10689

Working Principle of EXAFS Beamline

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Top view

Sheilding Wall

Beam ApertureBerillyum Window

Slit System Pre-Mirror

Side view

Bent Crystal Polychromator

Slit System

Sample

Detector

Source

Optical Lay-out of EXAFS BeamlineUsed for vertical focusing –cum-higher harmonic rejection

Used for horizontal focusing –cum-dispersion

BW-1

BW-1

Optical Layout of EXAFS Beamline at INDUS-2

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Design Procedure• Fixed parameters

• Variable geometrical parameters

• Ray tracing : check the performance

• Fixing the specs of optical components

• Simulation of heat load on each optical components

• Mechanical specs of different subsystem» Mirror mount, crystal bender et

• Simulation of radiation dose

• Fixing specs of Hutch

Ref.: N.C. Das, S.N. Jha,& D. Bhattacharyya, Proc. 8th International Conference on SRI, AIP conference proceedings, 705, 301(2003)

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Fixed ParametersCrystal type Si (111)

2d Value 6.2709 Å

Source to Crystal Distance (p)

20,000 mm

Detector length (L)

25 mm

Horizontal Beam Divergence (Um)

1.5 mrad

Vertical Beam Divergence

0.2 mrad

12.3982 2 ( )o

o

Sind dE keV

λθ = =

( )m o

lU Sin

pθ=

1( )o

o o

SinE E lCot

R p

θθ∆ = −

1 1 1( )

2o

R

Sin p qθ= +

'm

Lr

U=

' ( )m o

lU Sin

qθ=

Eo

θο

p, Um, θο

ll, θο , ∆E , p

R

R, p, θο

ql, q, θο

L, Um'

Um'

P.M. Lee etal, Review Scientific Instrum, 65,1(1994)

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Derived Parameters

Photon Energy Eo (eV) 5000 10,000 20,000

Band Pass ∆∆∆∆E (eV) 297 1123 2000

Bragg Angle (θθθθo) 23.28º 11.40º 5.67ºCrystal length

l (mm)75.9 151.8 303.5

Crystal Radius R (mm) 2803 6287 26,550

Crystal to Sample distance

q (mm)570 641 1404

Sample to Detector

Distance r (mm)475 534 1170

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Ray tracing result

5 keV 10 keV 20 keV

Focal spot 20 40 50

Spatial resolution at detector

0.3eV/pixel 1.1eV/pixel 2.1eV/pixel

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Optical components

• Polychromator

• Pre-mirror:

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Polychromator

Crystal BenderGenerates elliptical curvature on a

profiled crystal of ½ m length Mean Radius of Curvature: 2 m to 20 m (within +/-0.5%)

Actual bender inside a vacuum chamber with Ga/In based cooling arrangement

460 mm long profiled Si (111) Crystal ;Darwin width: 0.6 arc sec

Indigenously built

Stepper motor driven shaftsStroke: 0-12 mm (required 3-4 mm)Resolution: 0.5 µµµµm

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Harmonic Rejection Mirror :

Substrate: Si Coating: Rh Radius: 1319 mSize : 1 m × 30 mm Surface Roughness: 3 Å r.m.s.

Grazing incidence Cylindrical Mirror

Side cooled, gravity compensated

0 5000 10000 15000 20000 25000-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Rh

C

B

A

Refl

ecti

vit

y

photon energy (eV)

A: 0.2o

B: 0.4o

C: 0.6o

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Mirror

Indigenously built Mirror chamber with

mirror mount

Movement resolution of mount Shafts inside UHV : 1µm

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Floor Level

SIP1HV

P.S.

RGA(RS232)

SIP

135

175

1400

360

SIP

175

SIP24

0

175

SIP

G.L.

132

GONIOMETER

250

140

Beam Aperture Chamber

1st Bean View ChamberPrecision Slit System

Mirror Chamber

2nd Beam View Chamber

Bender Chamber

Crystal BenderFront EndSample Mount

Detector Mount

Mechanical layout of EXAFS BL at Indus-2

Be-1

Be-2 Be-3

Experimental station

Sample stageExperimental station

Shielding wall

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Commissioning stages

• Alignment of Front-end with SR • Integrating the front end with beamline and achieving

vacuum in subsystems• Optical Alignment of with SR using BV systems and

CCD detector • Checking the SR foot prints at different locations of

the beamline• Checking the performance of the bender• Recording absorption of standard samples to check

the spatial resolution and band pass energy

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275 mm

Beam reflected from mirror which is used

Direct Beam which is blocked

Illumination on crystal for 20 keV setting

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Beam spot at sample position

200µm

500µm

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19800 19900 20000 20100 20200 20300 20400 205000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7µ

Energy (eV)

Absorption Spectra of Mo Foil **20 keV Setting12.03.08@ 6 ma/2 GeV

**Complete Spectrum Taken In 1 Second

First EXAFS Signal

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Mo-Nb

1600 1500 1400 1300 1200 1100 1000 900 800 700 6000.0

0.5

1.0

1.5

2.0

2.5

3.0µ

Channel No

Mo Absorption Edge20000 eVChannel No: 1067

Nb Absorption edge 18987 eVChannel No: 1577

Mo & Nb absorption edge obtained at 20 keV setting

Calibration: 1.98 eV/channel

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Mo MoO3

19800 20000 20200 204000.0

0.4

0.8

Reported Difference in E0: ~9 eV

E0(Athena: Half Edge step)

= 20000.97 eV

MoO3 µµ µµ

Energy (eV)

Mo

E0(Athena: Half Edge step)

= 20010.31 eV

D. Lutzenkrichen-Hecht and R. Frahm, J. Synch. Rad., 6 (1999) 591.

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Chemical shift

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EXAFS Spectra of Bi2O3 taken at LIII edge13keV setting

0.6eV/pixel( Pb-LIII and Bi-LIII)

EXAFS MEASUREMNENTS

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�U(VI) sorbed on alumina and kolinite��Crystalline PbCrystalline Pb55GeGe33OO1111

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X-ray Absorption Spectroscopy of U(VI) sorbed onto Alumina

Sorption of U(VI) by alumina and kaolinite at

varying pH has been studied by X-ray

absorption Spectroscopy. The absorption

intensity was found to increase with increasing

pH of the suspension.

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17000 17100 17200 17300 17400 17500 17600 17700 17800

0.0

0.2

0.4

0.6

0.8

1.0

µµ µµ

Photon energy(eV)

0 2 4 6 8 10

0.0

0.2

0.4

0.6

0.8

F

ou

rier

tran

form

R(A0)

Fourier transformed spectra of alumina-3 (pH=7)

X-ray absorption spectrum of U(VI) sorbed onto Alumina

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Conclusion:

Results from newly developed EXAFS beamline at Indus-2 are found to be in good agreement with those reported in literature which implies the satisfactory performance of the beamline.

Further efforts are being made to improve the signal to noise ratio.

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– Dr. S. Banerjee, Director BARC, Mumbai– Dr. V.C. Sahni, Director, RRCAT– Dr. S.M. Sharma, Coordinator, “Development of Indus-2

beamlines” Project– Dr. N.C. das– A.K. Sinha, V.K. Mishra– Dr. A.K. Ghosh & Mr. Vishnu Verma– Mr. Sanjay Chouksey– V.K. Raghuvanshi, S.R. Kane and Dr. S.K. Deb– Mr. Vijendra Prasad, Beam alignment section, – Dr. A.K Tyagi, A. Singh, Dr. B.S. Tomar– Indus-operation staff– Mr. K.K. Thakkar, health physicist – M/s. SMP Enterprises, Pune, India– M/S. Integrated Automation Systems Pvt. Ltd. Mumbai

Acknowledgements