Confocal Micro-XRF and XRF imaging based on polycapillary ... · Conventional micro-XRF Confocal micro-XRF Polycapillary lens attached to the EDS collects the x-rays emitted from

Confocal Micro-XRF and XRF imaging

based on polycapillary optics

Kouichi Tsuji, Osaka City University, Osaka, Japan

1) Confocal m-XRF imaging

(focusing polycapillary)

2) FF-XRF imaging with x-ray camera

(straight polycapillary as angular filter)

Overview

DXC2018 Workshop: Micro XRF, K. Tsuji

1) Confocal M-XRF

2DXC2018 Workshop: Micro XRF, K. Tsuji

Point analysis Line analysis

Micro-ＸＲＦ analysis

Elemental mapping

3

X-ray tubeDetector

Ar

Micro x-ray beam is created by

using polycapillary focusing optic.

X-ray fluorescence emitted on the

path of micro x-ray beam is

detected.


Conventional micro-XRF Confocal micro-XRF

Polycapillary lens attached to the

EDS collects the x-rays emitted

from the confocal point.

Nondestructive depth-selective XRF

analysis is possible.

Micro x-ray

beam

XRF

XRF

Polycapillary

X-ray half lens

for collecting XRFEDS

X-ray scattering

XRF, not detected

⚫Small region can be analyzed

using x-ray focusing optics,

such as polycapillary optics.


W.-M. Gibson, M.A. Kumakhov,

Proceedings of SPIE, 1736, 172-

189 (1993).

Idea of confocal M-XRF

X. Ding, N. Gao, G. Havrilla,

Proceedings of SPIE, 4144,

174 (2000).

B. Kanngieber, W. Malzer, I. Reiche,

Nucl. Instr. and Meth. in Phys. Res.

B, 211, 259 (2003).

Confocal micro-XRF instrument


Cu wire

Polymer insulator

Cable coated with

polymer insulator

1 m

m

7

Confocal m-XRF analysis of Electric cable

2 mm


0

500

1000

1500

2000

1 3 5 7 9 11 13

Cu wire

XR

F in

ten

sit

y / c

ou

nt

Energy / keV

0

100

200

300

400

1 3 5 7 9 11 13

Cu

K

Pb

L

Pb

L

FeK

PVC coating

XR

F in

ten

sit

y / c

ou

nt

Energy / keV

DetectorX-ray beam

Depth-selective X-ray spectra of electric cable

Cu wire

8


Vacuum Chamber

Detector

X-ray tube

CCD

C-M-XRF with vacuum chamber at OCU


10

Baseplate

Sample stage

Stage

Polycapillary

X-ray optics

Detector snout

Vacuum chamber

Door

Stage

T. Nakazawa and K. Tsuji, Development of a high resolution confocal micro-XRF

instrument equipped with a vacuum chamber, X-Ray Spectrom., 42 (2013) 374-379.

C-M-XRF with vacuum chamber at OCU

The sample is placed

horizontally.

Side view


Confocal-XRF setup

Sample

X-Ray Spectrom., 42 (2013) 374-379.

Polycapillary X-ray lens

Polycapillary full lens for primary x-ray beam

- Focal spot size: ≤10 mm, [email protected]

Input focal distance : 30.0 mm

Output focal distance : 2.5 mm

Optic enclosure length: 99.5 mm

12

Polycapillary half lens for detection of XRF

- Focal spot size: ≤10 mm, at 17.4 keV

Input focal distance : 3.0 mm; Outer diameter : 10 mm

Optic enclosure length: 36 mm


Confocal volume

Primary x-ray Fluorescent

x-ray

A depth resolution of the confocal micro-

XRF spectrometer can be evaluated by a

thin layer scanning method.

Si substrate

thin film (layer)

≃Corresponding

Depth resolution

Newly developed thin metal layersX

RF

inte

nsity

Scanned distance

surface depth

FWHM : estimated from XRF intensity profileTfoil : thickness of the thin layer

Evaluation of confocal volume and depth resolution

X-Ray Spectrom., 42 (2013) 374-379.

Standard thin layers

Mo Ti Al

Cu Au Cr

Ni Fe Zn

⚫ These samples were prepared using a magnetron sputtering

technique at NTT-AT, Japan.

⚫ The certified thickness was determined with a stylus-type surface

profiler.

ElementEnergy (K-line)

Certified thickness

Al 1.487 480 nm

Ti 4.510 478 nm

Cr 5.414 498 nm

Fe 6.403 500 nm

Ni 7.477 517 nm

Cu 8.047 483 nm

Zr 15.774 493 nm

Mo 17.478 507 nm

Au 9.711 (L) 501 nm

Photograph of the thin layers

X-Ray Spectrom., 42 (2013) 374-379.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0

Dep

th r

eso

luti

on

/ m

m

Energy / keV

Depth resolution

Mo

Au

Confocal setup in vacuum

Confocal setup in air

X-Ray Spectrom., 42 (2013) 374-379.

Confocal micro-XRF spectra in air and in vacuum

1

10

100

1000

10000

100000

0 2 4 6 8 10 12 14

XR

F In

ten

sity

/ 1

00

0 s

ec

Energy / keV

air

vacuum

NIST SRM 621

Na

Al

Si

S Fe

K

As

Ca

Ca

Ba, Ti

Rh

16

Si

(Mo target)

(Rh target)

In air

In vac.


LLDs of

confocal setups

for SRM621

(glass standards)

in air and in

vacuum

Element In air [ppm]

In vaccum[ppm]

Na - 5504

Al - 80

Si 17842 46

S 254 46

K 91 36

Ca 47 28

Fe 7 19

W : concentration (%)t : measuring time (s)INet : net intensity(cps)IBG : background intensity (cps)

QXAS, developed by The IAEA

Seibersdorf Laboratories, was

used for analysis.

Shaping time: 3 ms (SRM621),

18

Confocal micro-XRF analysis in air and in vacuum


Secondary effects

in confocal M-XRF


Secondary excitation in XRF analysis

X-ray

Fluorescence


Secondary excitation in confocal m-XRF setup

Layered sample

Depth scan (Polyimide film)

Cu (5 mm)

Co (25 mm)

Cu (5 mm)

Kapton

Kapton

Cu K can excite Co K.Si wafer substrate

Fe K absorption edge Co K absorption edge

Ni K absorption edge

Secondary excitation of Co by Cu

Thickness of Kapton film was 0, 7.5, 75, 150 mm

Without Kapton film With Kapton film of 7.5 mm

With Kapton film of 75 mm With Kapton film of 150 mm

Cu

(5 m

m)

Co (

25 m

m)

Cu

(5 m

m)

Kap

ton

Kap

ton

Shoulder peak Additional peak 38

③①Cu

②

Co

③

Cu

Co

Kapton

Kapton

Analytical point

Primary X-rayDetector

Secondary excitation process in confocal m-XRF

Fluorescent X-ray of CuPrimary X-ray

Fluorescent X-ray of Co

②

Analytical volume②③①

Cu Foil

Co FoilKapton


Step 1

Step 2 Step 3

Ti

Ti Ti

K. Tsuji, A. Tabe, P. Wobrauscheck

and C. Streli, Powder Diffraction, 30

(2015) 109-112.

Simulation of confocal M-XRF intensity


0

5

10

15

20

25

30

-100 -80 -60 -40 -20 0 20 40 60 80 100

Z=-40μm

TiKa CuKa

0

5

10

15

20

25

30

-100 -80 -60 -40 -20 0 20 40 60 80 100

Z=-40μm

TiKa CuKa

0

50

100

150

200

-100 -80 -60 -40 -20 0 20 40 60 80 100

Z=41.0μm

CuKa TiKaP TiKaS

0

50

100

150

200

-100 -80 -60 -40 -20 0 20 40 60 80 100

Z=41.0μm

CuKa TiKaP TiKaS

Cu - Ti Ti - Cu

Exp

erim

en

tal

Sim

ula

tio

nComparison of Experimental and simulation profiles

Analyzing depth: 40 mm in depth

Cu

Ti Cu

Ti


Wire sample

8 mm Stainless steel frame

Double-sided tapePP base adhesive tape5 μm Polypropylene film

φ30 μm Cu wireφ30 μm Fe wire

Cross sectional view

Fe Cu

Top view

Confocal point


In air

Comparison of Experimental and simulation maps

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100

-60

-40

-20

0

20

40

60

80

100

Cu K

X /μm

Z /

μm

0.2512

0.3981

0.6310

1.000

1.585

2.512

3.981

6.310

10.00

15.85

25.12

39.81

63.10

100.0

158.5

251.2

398.1

631.0

1000Fe K

Wire distance ~156 μmExperimental Simulation


Applications of C-M-XRF


30

◆ Micro analysis of small volume

◆ Analysis of inside of the sample in solid or

solution

◆ Elemental depth profiling

◆ Depth XRF imaging (cross sectional)

◆ Depth-selective XRF imaging

Advantages of confocal m-XRF in the laboratory


1 st

2nd

3rd

4th

Base

1st

4th

3rd2nd

5th

6th

7th

8th

1st2nd

5th

3rd

4th

Sample No.1: Red paint Sample No.3: Blue paint

1 mm 1 mm3 mm

Sample No.2: Black paint

Thickness: 110 mm Thickness: 170 mm Thickness: 280 mm

Elemental depth profiling of paint chip of car

Surface coating paint chips of cars after car traffic accidents

(Forensic Science Laboratory, Hyogo Prefecture Police Headquarters, Japan)

31Optical microscope images of cross-sections after angle-polishing.

0.0

0.2

0.4

0.6

0.8

1.0

0 50 100 150 200 250 300 350

: Fe

: Zn

: Ti

: Cu

: Cl

: K

No

rmalized

in

ten

sit

y / a

.u.

Scanned distance (Depth) / mm

1st Base2nd 3rd 4th 6th – 8th

Elemental depth profiling of car paint chip

Cl :automotive topcoat, K :mica, Fe

Cu, Cl: CuPc, K: micaTi: TiO2, Fe: Fe2O3, FeTiO3

Cu, Cl: CuPc,: K: micaTi: TiO2, Fe: Fe2O3, FeTiO3

K: mica, Zn: ZnO, Ti: TiO2, Fe: Fe2O3, FeTiO3

Zn corrosion inhibitor

Zn, Fe: zinc-coated steel plate

1st

2nd

3rd

4th

6-8th

Base

1 mm

Layer structure of paint chip

Surface

5th

CuPc: Cu-phthalocyanine

Anal. Chem., 83 (2011) 3477-3483

Automobile paint chip at car traffic accident was analyzed

in cooperation with Japanese police forensic laboratory.

Analytical modes by Confocal M-XRF

Depth selective

elemental mappingCross sectional,

Depth elemental imaging


213

0

Inte

nsi

ty /

cp

s

1448

0

Inte

nsi

ty /

cp

s

Red：200 cpsBlue：100 cps

Red：1300 cpsGreen：800 cps

Elemental images obtained by micro-XRF

Ni KAu L

Contact pad Contact pad

34

11 mm

15

mm

Micro-SD memory card

used for mobile phone

Thickness : 0.8 mm

Elemental imaging of the

industrial materials is

important for defective and

quality examination.

X-Ray Spectrom., 42 (2013) 123-127.

50 kV- 0.5 mA

Mapping area: 11 × 15 mm

Step size : 100 mm, 10s/ step

252

0

Inte

nsi

ty /

cp

s

2238

0

Inte

nsi

ty /

cp

s

149

0

Inte

nsi

ty /

cp

s

(Yellow：1600 cps) (Blue：60 cps)(Green：100 cps)

Ti K Cu K Br K

Elemental images obtained by micro-XRF

Ti : hard plastics Cu : printed circuit Br : epoxy resin

35

X-Ray Spectrom., 42 (2013) 123-127.

36

20 mm 35 mm 50 mm 65 mm 90 mm 120 mmSurface Inside

Mic

ro-X

RF

3D–X

RF

Depth selective elemental imaging(micro SD memory card) Cu K image

Depth = 35 mm Depth = 90 mm

1st printed circuit near surface

X-Ray Spectrom., 42 (2013) 123-127.

37

Monitoring of chemical reactions in the

solution by confocal m-XRF

Advantages of confocal m-XRF

In situ XRF analysis of the inside of the sample

in solutions.

➢ K. Tsuji, T. Yonehara, K. Nakano, Application of confocal 3D micro XRF for solid/liquid interface analysis, Anal. Sci., 24 (2008) 99-103.

➢ S. Hirano, K. Akioka, T. Doi, M. Arai, and K. Tsuji, Elemental depth imaging of solutions for monitoring corrosion process of steel sheet by confocal micro-XRF, X-Ray Spectrom., 43 (2014) 216-220. (monitoring of

corrosion process)


Analytical modes by Confocal M-XRF

Depth selective

elemental imagingCross sectional,

Depth elemental imaging

38

Liquid

Solid


SampleX-ray tube

SDD

Confocal Micro-XRF setup and sample

Mo target, 50 kV, 0.6 mA

X-ray tube

MCBM 50-0.6 B (rtw, Germany)

Sens. area: 50 mm2 <130 eV at Mn Ka

Polycapillary X-ray lens (XOS) :10 mm

Vortex EX-60 (Hitachi high-tech science co.)

SDD and lens

Spatial resolution: 14.5 mm＠Au Lα

Steel sheet with plating Zn layer

Thickness

C Si P

Mn Fe

Al Fe Zn

P Mn Ni Zn

Al Si Ti SnCoating layer

Chem. conversion

Plating Zn layer

Steel sheet

15 mm

2 ~ 3 mm

10 mm

Element

Scratch

X-ray tube (Mo)

SDD

X-Y-Z stages

Sample

3.5% NaClsolution

450 mmKapton

Sample cell and experimental procedure

Teflon (PTFE) case

40

CupCap

Polycapillaries

Steel sheet was placed in the sample

cell.

NaCl solution (3.5 mass%) was filled

in the sample cell.


Scanned distance / mm

Fe

Ti

Zn

Mn

NaCl solution

Steel sheet

0

200

400

600

0

200

400

600

0

200

400

600

0

200

400

600Sca

nn

ed

dis

tan

ce in

dep

th / m

mElemental maps in 0-24 hours (after one day)

24 hours / image

Start

End

Analyzed area: 1680 mm x 600 mm

Step size : 15 mm x 10 mm

Scratch

Zn

Mn

Fe

Ti

0

200

400

600

0

200

400

600

0

200

400

600

0

200

400

600

Elemental maps in 96-120 hours (after 5 days)

Pre-blister was

observed


Scan

ned

dis

tan

ce

in

dep

th / m

m

Zn

Mn

Fe

Ti

0

200

400

600

0

200

400

600

0

200

400

600

0

200

400

600

Elemental maps in 120-144 hours (after 6 days)

Blister-type corrosion

was observed


Scan

ned

dis

tan

ce

in

dep

th / m

m

Fe and Zn were dissolved and enriched inside the blister.

Zn

Mn

Fe

Ti

0

100

200

300

400

500

0

100

200

300

400

500

0

100

200

300

400

500

0

100

200

300

400

500

Dissolved Fe, Zn, and Mn were diffused into the solution.

Elemental maps in 192-240 hours (after 9-10 days)


Scan

ned

dis

tan

ce

in

dep

th / m

m

Zn

Mn

Fe

Ti

0

100

200

300

400

500

0

100

200

300

400

500

0

100

200

300

400

500

0

100

200

300

400

500

Elemental maps in 240-288 hours (after 11-12 days)


Sca

nn

ed

dis

tan

ce in

dep

th / m

m

Zn, Fe and Mn under the blister were diffused in the

solution, and enriched near the Kapton film.

Corrosion process was successfully visualized.

2) FF-XRF imaging

with x-ray camera


X-ray fluorescence imaging

Scanning type XRF imaging

Polycapillary lens

Primary

X-rays

Full Field type XRF imaging

Primary X-rays

2D detector

SDD◆ Micro x-ray beam is created.

◆ XRF image is obtained with

high spatial resolution.

◆ Scanning process needs a

long acquisition time.

◆ X-rays irradiate a large area

of a sample.

◆ X-ray camera is applied for

taking x-ray images (gray

scale image).

⚫ WD-XRF imaging spectrometer

⚫ ED-XRF imaging camera

Spectroscopic techniques

2q

q

Sample

Soller

slits

S.C.

P.C.

X-ray

tube

Dispersive

crystal

Conventional WD-XRF

Bragg's law：2d sinq = nl

Diffracted

x-rays

48

Soller slits


Analyzing crystal

Primary

X-rays

X-ray tube

Sample

X-ray fluorescence

Entrance

straight

polycapillary

X-ray

2D-detector

Exit straight

polycapillary

Concept of WD-XRF imaging spectrometer

K. Tsuji, et al, Anal. Chem., 83 (2011) 6389-6394.

K. Tsuji. et al. Spectrochim. Acta, Part B, 83-84 (2015) 43-53.49

Previous results were reported in the following papers:

2D collimator2d sinq = nl


WD-XRF imaging spectrometer

θ2θ

Vacuum chamber (20 Pa)X-ray tube

W target

50 kV, 60 mA

SampleStraightpolycapillary

24 mm

Polymer window

Based on Rigaku RIX-1000

Straight polycapilalry（XOS）

5.0 µm

10.7 mm

Length :10.5 mm


PLATUS detector was applied

X-ray images with diffraction angles


45.03 °(Cu Kα) 45.5 ° 46.0 ° 46.5 °

47.5 ° 48.5 ° 48.65 °(Ni Kα)48.0 °

10 mm 10 mm 10 mm

10 mm 10 mm

10 mm

10 mm 10 mm

0 170 ( count )

10 mm

Ni (50 mm)

Cu

A triangle Ni thin film (50 mm in thickness) was places on a Cu sheet.

Exposure time for each image: 1 s

48.645 °48.545 °

48.445 °

48.745 °

48.845 °

49.345 °49.245 °49.145 °

49.045 °48.945 °

47.945 ° 48.045 ° 48.145 °

48.245 ° 48.345 °

W target

60 kV , 50 mA

Exposure time : 60 s

In air

2θ (deg.)

Inte

ns

ity (

cp

s/p

ixe

l)

FWHM

= 0.545 °

77 eV at Ni K (7.47 keV)

Energy resolution

10 mm

Ni (50 mm)

Cu


Ni K

Cu K

Zn K

1 s0.5 s0.1 s

48.65°

45.01°

41.78°

Exposure timeW target

50 kV , 60 mA

53

Elemental images of 1 Euro coin

K. Tsuji. et al.

SAB, 83-84

(2015) 43.


FF-ED-XRF imaging spectrometer

Fig. 2. Energy response of the CCD detector. CCD counts indicate the raw and digitized data generated by the analog to digital converter of the CCD.

Fig. 3. The fluorescence spectrum of Fe measured using the X-ray pinhole camera. The energy resolution is 157 eV at Fe–Kα line.

F. P. Romano, et al., Spectrochimica Acta Part B, 86 (2013) 60–65.

Photon counting


< Straight polycapillary

by XOS >

X-ray ShutterMo target

(30 kV, 2mA)

X-ray

tubeX-ray

CCD

e-

e-

FF-ED-XRF imaging spectrometer

⚫ Backside illumination type⚫ Pixels : 1024 pixel x 1024 pixel

(512 x 512), (256 x 256)⚫ Pixel size : 13 mm x 13 mm⚫ Area : 13.3 mm x 13.3 mm⚫ Cooling : - 90 ℃

Andor iKon-M

e-


To perform a single photon counting,an x-ray shutter was used.A straight polycapillary gives 1:1 imagefor the sample to the CCD.

4

12 mm

25 mm

20 m

m

< Straight polycapillary (XOS) >

Optic dimention(flat to flat) 20 mm

Channel diameter 12 mm

Enclosure Diameter 25 mm

Optic length 13 mm

Open area 65 %

Straight polycapillary as angular filter


y = 6.4288x + 107.43R² = 0.9627

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28En

erg

y r

eso

luti

on

/ e

V

Energy / keV

142 eV @ Fe K

⚫ Mo tube : 30 kV, 2 mA

⚫ Pure metals: Ag, Au, Co, Cu,

Fe, Ni, Ti, Zn

⚫ Exposure time: 1s / frame

⚫ Total frames: 100 frames

⚫ 256 pixel x 256 pixel Inte

nsit

y /

co

un

ts

Energy / keV

XRF spectrum of

pure Fe metal

FWHM

Energy resolution


Element

FWHM (mm)

256 x 256

(Bin = 4)

512 x 512

(Bin = 2)

Co K 337 51

Cu K 241 33

Fe K 352 52

Ni K 297 41

Pb L 150 16

Ti K 521 73

Zn K 241 30

⚫ Mo tube : 30 kV, 2 mA

⚫ Pure metals: Co, Cu, Fe, Ni, Ti, Zn foils

(50 mm in thickness), and Pb (1 mm)

⚫ Exposure time : 1 s / frame

⚫ Total frames: 900 frames

⚫ Effective pixels : 256 pixel x 256 pixel

512 pixel x 512 pixel

13.3 mm

Image of

Cu K13.3 mm

0

70

90

110

130

150

170

0 20 40 60 80 100 120

Inte

nsit

y /

co

un

ts

pixel

0

25counts

FWHM

Spatial resolution

0

2000

4000

6000

8000

0 5 10 15 20

Cu K

Cu K

Pb L

Br KPb L

Br K

Energy （keV）

Inte

nsit

y （

co

un

ts）

⚫ Mo tube:

30 kV, 10 mA

⚫ Exposure

time: 0.05 s

⚫ Total frames:

9000 frames

⚫ 256 pixel x

256 pixel

FF-ED-XRF imaging of electronic circuit card

5 mm2 mm

Ti K Counts

Total exposure time: 7.5 min.

⚫ Mo tube:

30kV, 10 mA

⚫ Exposure

time: 0.05 s

⚫ Total

frames: 9000

frames

⚫ 256 pixel x

256 pixel

FF-ED-XRF imaging of electronic circuit card

5 mm2 mm

Simultaneous elemental images were obtained.

Total exposure time: 7.5 min.

Scanning type FF (projection) type

SEM-EDS (C)-M-XRF WDXRF ED-camera

Source Electrons X-ray tube X-ray tube X-ray tube

scanningElectron beam

scanningSample scanning

Without scan

(but angle scan)Without scan

Spatial

resolution1 mm 10 mm ~ 300 mm < 50 mm

Energy

resolution~ 140 eV ~ 140 eV < 70 eV (~ 40 eV) ~ 140 eV

AdvantageHigh spatial

resolution

3D analysis by C-

M-XRF

Short exposure time

(~ 1 s)

High energy-reso.

Simultaneous multi-

elemental imaging

Drawback

Vacuum

Damages

Electrical

conductivity

Long acquisition

time for large

sample

Large equipment

Ange scan

Photon counting for

weak x-rays

Long acquisition time

Comparison of XRF imaging techniques


Summary• Scanning-confocal M-XRF was applied for

elemental depth profiling, depth-selective XRF imaging, also monitoring the corrosion process of the steel sheet in the solution.

• FF-WD-XRF imaging was introduced. The advantage of this technique is a fast imaging less than 1 s with good energy resolution.

• FF-ED-XRF imaging with CCD camera was introduced. Elemental distribution on the surface was imaged through straight polycapillary (angular filter) by single photon counting analysis.


Documents

Confocal Micro-XRF and XRF imaging based on polycapillary ... · Conventional micro-XRF Confocal micro-XRF Polycapillary lens attached to the EDS collects the x-rays emitted from