A Shimadzu Group Company Kratos AXIS Ultra DLD The small spot, parallel imaging, multi-technique...

A Shimadzu Group CompanyA Shimadzu Group Company

www.kratos.com

Kratos AXIS UltraDLD

The small spot, parallel imaging, multi-technique photoelectron spectrometer

Dr Chris Blomfield

Applications of high resolution XPS & AES


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Kratos Analytical Ltd

Kratos headquarters Manchester UKservice/sales centresNew York, Tokyo,Singapore, Frankfurt


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• ES-100 launched 1969• XSAM series 1980-90• Axis series launched 1995

– Axis HS 3 detectors 35– Axsi HSi 5 detectors40– Axis 165 8 detectors 45– Axis Ultra imaging 195– Axis Nova 40

Total units 355

All featuring common Axis technology– Virtual probe– Magnetic lens– Coaxial charge neutraliser– Spectral resolution and sensitivity

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69

ES-100 ES-200 ES-

300

XSAM series HS

19

84

20

04

AXIS NovaAXIS UltraDLD

20

03

AXIS Ultra

19

97

AXIS 165

19

94

AXIS HSi

19

91


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What is the surface?

• What happens at surfaces is extremely important in a vast range of applications from environmental corrosion to medical implants.

• A surface can be thought of as the interface between different phases (solid, liquid or gas).

• We can think of the surface as the top layer of atoms but in reality the state of this layer is very much influenced by the 2 – 10 atomic layers below it (~0.5 – 3 nm).

• Surface modification treatments are often in the range of 10 – 100 nm thick. >100 nm can be thought of as the bulk.

• Surface analysis encompasses techniques which probe the properties in all these ranges.


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• Properties and reactivity of the surface will depend on:

• bonding geometry of molecules to the surface

• physical topography

• chemical composition

• chemical structure

• atomic structure

• electronic state

No one technique can provide all these

pieces of information. However, to

solve a specific problem it is seldom

necessary to use every technique

available.

photons

ions

electrons

EMISSION

TRANSMISSION

Interaction with material

EXCITATION

Surface Analysis - Techniques Available


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Analytical Technique Signal Measured Elemental Range Depth Resolution Surface info.

SIMS Secondary Ions H-U 5 - 30 Å Chemical composition

(secondary ion mass spectrometry) Chemical structure

TOF-SIMS Secondary Ions H-U, Large Organic 2000 Å (Scanning Mode) Adsorbate bonding

(time-of-flight SIMS) Molecules / Cluster Ions

TEM Transmitted Electrons X-Rays Na-U EDX N/A

(transmission electron microscopy)

FE-SEM, EDX Backscattered or Na-U 1 - 5 micrometres

(field emission SEM) Secondary Electrons and X-Rays

ISS Ions H- U monolayer atomic structure

(ion scattering spectroscopy) chemical composition

AES/SAM Auger Electrons Li-U 1 - 5 nm chemical composition

(Auger electron spectroscopy, scanning Auger microscopy)

ESCA/XPS Photoelectrons Li-U 1 – 10 nm chemical composition

(electron spectroscopy for chemical analysis, X-ray photoelectron spectroscopy) chemical structure

RAIRS IR photons organic, some inorganics monolayer Adsorbate bonding

(reflection-absorption infra-red spectroscopy)

STM - solid surfaces upper most atoms physical topography

(scanning tunnelling microscopy)

Analytical Technique Signal Measured Elemental Range Depth Resolution Surface info,



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Surface Sensitivity of XPS

• Penetration depth of the X-ray radiation is 102-103 nm.• However, the surface sensitivity of XPS arises from the short distance the photoelectrons

can travel in the solid before suffering inelastic scattering. • The average distance from the surface a photoelectron can travel without energy loss is

defined as the inelastic mean free pathlength (IMFP), λ.• Sampling depth, d, defined as the average distance from the surface for which 95% of

photoelectrons are detected, d = 3λ.

dPhotoelectrons out

X-rays in

d = 3λ


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What information do we get from XPS?

• Surface sensitivity - photoelectron signal from first 1-10 layers of atoms and molecules.

• Identification of all elements (except H & He) at concentrations >0.1atomic%*.

• Quantitative determination of the elemental composition.• Information about the chemical state (molecular environment)

of the element.• Non-destructive analysis, including depth profiles, from the top

10 nm.• Destructive depth profiles of inorganic materials for 100s of nm.• Lateral variations in surface composition at >3µm resolution.• ‘Finger printing’ of materials using valance band.

• *Sensitivity - a sample with a surface of size 1 cm2 - this will have ca. 1015 atoms in the surface layer. In order to detect the presence of impurity atoms present at the 1% level, a technique must be sensitive to ca. 10 13 atoms. Contrast this with a spectroscopic technique used to analyse a 1 cm3 bulk liquid sample i.e. a sample of ca. 1022 molecules. The detection of 1013 molecules in this sample would require 1 ppb (one part-per-billion) sensitivity - very few techniques can provide anything like this level of sensitivity.


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The X-ray Photoelectron Spectroscopy Experiment

• Prof. Kai Siegbahn, Uppsala University, pioneered the technique of XPS, producing the first well defined spectrum in 1954 & was awarded a Noble prize for his work in 1981.

• Since then the basic building blocks of the X-ray photoelectron spectrometer have not changed.

• However, UHV technology and electronics have improved!

X-ray source

UHV analysischamber

Electron energy analyser

Electron detector

sample


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The Photoelectron Spectrum – Surveys/Wide ScansWhich elements are present and how much have we got?

Cu 2p

O KLL Auger

O 1s

N 1s

C 1s

Cu LMM Auger

Cu 3p

Cu 3sCl 2p

Cl 2s

• The energy of the photoelectron peak is indicative of the element from which it originated.

• The number of electrons (peak area) is related to the elemental concentration.

• Both photoemission and Auger peaks observed in a spectrum.

• Peaks are superimposed on a rising background, due to inelastically scattered photoelectrons.


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O 1s

C 1s

O KLLAuger

O 1s C 1s

The Photoelectron Spectrum – High ResolutionWhat chemical state are the elements in?

High resolution spectra show the subtle shifts

in energy of photoelectrons originating form

different chemical environments.


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Chemical State Information

• The binding energy of an electron is dependent on the atomic orbital the electron occupies and the chemical environment of the atom.

• The variation of binding energy of a specific photoemission peak provides information on the chemical state of the atom or ion.

Core level electron, high binding energy

Valence electron, low binding energy


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Chemical State Information

• Typical binding energies for C 1s photoemission peaks from organic materials

• functional group binding energy (eV)

• hydrocarbon C-H, C-C 285.0• amine C-N 286.0• alcohol, ether C-O-H, C-O-C 286.5• fluorocarbon C-F 287.8• carbonyl C=O 288.0• 2F bound to a carbon -CH2CF2- 290.6• 3F bound to a carbon -CF3 293-294

• Typical chemical shifts for O 1s photoemission peaks from organic materials

• functional group binding energy (eV)

• carbonyl -C=O, O-C=O 532.2• alcohol, ether -O-H, O-C-O 532.8• ester C-O-C=O 533.7


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Quantitative Surface Analysis of Poly(ethylene tetraphthalate) - PET Large Area Survey

O KLL

Peak Position FWHM Raw Area RSF Atomic Atomic Mass BE (eV) (eV) (CPS) Mass Conc % Conc % C 1s 282.000 3.181 1988710.0 0.278 12.011 74.54 68.73 O 1s 530.000 3.623 2089951.0 0.780 15.999 25.46 31.27


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Quantitative Surface Analysis of Poly(ethylene tetraphthalate) - PET Chemical State Information

C 1s region O 1s regionO(1) 530.8eV 49 at% O(2) 532.1eV 53 at%

C(1) 285.0eV 61 at%C(2) 286.5eV 21 at%C(3) 289.2eV 18 at%

C3C2

C1 O1O2

-(-O-C- -C-O-CH2-CH2-)-= =

O On

2223

1

32

1

1


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Monochromated vs non-monochromated X-ray source

Monochromated Al Kα excited Ag spectrum

Non-monochromated Mg Kα excited Ag spectrum

FWHM 0.97 eV

FWHM 0.46 eV

satellite

Things to note: loss of rising background, narrower peaks, loss of satellite peaks, movement of Auger peaks

Ag 3d

Ag 3p3/2

Ag 3p1/2

Ag 3p3/2Ag 3p1/2

Ag 3d5/2

Ag 3d3/2

Ag 3d5/2

Ag 3d3/2Ag 3d

Ag 3s

Ag 3s

Ag MNV Auger

satellite


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Beyond Large Area Spectroscopy

thin film

<10 nm

thicker layer or multilayers heterogeneous surface

angle resolved XPS depth profile parallel imaging selected area spectroscopy


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AXIS UltraDLD

•Research grade performance•energy resolution < 0.45eV•sensitivity and therefore detection limits

•Flexible multi-technique configuration•XPS, UPS, AES, ISS•Large selection of sample preparation

•240 instruments installed

•Unique DLD detector technology

•128 channel snap shot

•3um parallel imaging

•15um small spot


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Axis Ultra performance

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Resolution (eV)

Sen

siti

vity

(cp

s)

Hybrid 110um 55um 27um

5eV

40eV

10eV

20eV

80eV


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Instrument overview

1 Al monochromatic source2 Mg/Al achromatic source3 Low energy floating ion gun4 165mm radius HSA & SMA5 Transfer lens & aperture/iris6 TMP 250 l/s for STC

Options

7 10 kV Field emission source8 UPS lamp

1.2.3.

4.

5.

6.

8.7.


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Configuration

1 Al monochromatic source2 Mg/Al achromatic source3 Low energy floating ion gun4 CCTV camera port (not shown)5 Magnetic lens6 Ion pump offset from SAC7 TMP 250 l/s for STC

Options

8 10 kV Field emission source9 UPS lamp

1.

2.

3.

4.

6.

5.

7.

8.

9.


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Si 2p Spectrum – pass energy 5 eV

FWHM Si 2p3/2 0.367 eV

Peak height 5403 cpsPeak fitted spectrum Si 2p3/2

Si 2p1/2

oxides

Native oxide


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Large area (700 x 300 microns) Ag 3d5/2 Fermi Edge spectrum recorded at 5 eV pass energy and 600 W X-ray power.

16% - 84% Edge resolution = 0.233 eV

Ag Fermi edge - RT – pass energy 5 eV

Ag EF < 250meV


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Ag 3d5/2 peak resolution (FWHM) = 0.445 eV, ~250KCPS

Ag 3d5/2 – pass energy 5 eV


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High sensitivity means high detection limits or fast analysis time


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Typical high sensitivity available

• Improved detection limits <0.05% allow analysis of low concentrations of elements

– Al-Zn-In anodes are used to protect marine steel structures from corrosion.

– study with XPS of the active In element – reveals surface segregation to a maximum of 4% over 1 year

exposure


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Overlap with Ca 2s

In 3d3/2 used for quantification

Low concentration In 3d quantification


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XPS shows surface concentration of In during corrosion

• Cut anode surface used to represent bulk– XPS In 0.02wt%

– GDOES In 0.0185wt%

• As cast anode surface ~1wt% In• Corrosion tests show an increase to 4wt% over 1 year

simulated corrosion


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Analysis of insulators


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Origin of Charge Neutralisation Electrons

Magnetic Lens Pole Piece

(2) Charge balance plate (-ve potential)

(1) Filament

(3) Low Energy Electron Trajectory in the Magnetic Field

Sample

1) Electrons are thermionically emitted from the charge neutraliser filament.

2) Negative potential of the charge balance plate forces the charge neutralisation electrons towards the sample. There is no direct line of sight of the filament with the sample.

3) The low energy electrons are confined by the magnetic field of the magnetic immersion lens, following an oscillating path between sample and charge balance plate.

4) As sample develops a positive charge, charge neutralisation electrons are attracted to the surface.


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200 microns

800 micronsC 1s spectrum from wood fibres

Neutralisation of Rough Samples

The sample of wood pulp fibres shown in the optical image to the right would traditionally be an extremely difficult sample to charge neutralise. However, as demonstrated by the excellent resolution on the C 1s spectrum poses no problem with the AXIS co-axial charge neutraliser.


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Charge Neutralization

•Fully automatic system standard parameter for 99% of samples

•Simple software electron only source

•No Ar* ions

•Works on topographic samples

There are only three parameters to define for the charge neutralisation system.

Normal user operation of neutraliser


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Neutralization of Rough Samples

+++++

++++

+++

rough sample surface

Kratos neutralisation system - electrons following a spiral path

Collimated electrons or ions from a low energy electron/ion source

For a rough sample, parts of the surface may be shadowed from neutralisation electrons originating from a collimated electron gun so that the sample will only be partially neutralised. This is overcome by the Kratos charge neutralisation system, where the low energy electrons reach the sample from all directions as a result of their spiral trajectory


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Neutralization of Insulating samples

XPS performance on insulators for the UltraHSA is guaranteed by specification defined using a polymer. The standard used is PET (polyethylene terephthalate) which has the chemical structure shown. The specifications are defined as the cps from the CC,CH component at 285eV and the FWHM of the ester component ( C-C(=O)-O- ) at ca.289 eV.

700x300um 110um

0.68eV 16,000 2,500

1.0eV 135,000 12,000

1.3eV 200,000 20,000

resn area

Sensitivity of CC,CH component (cps)

FWHM of ester peak (eV)


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0

50000

100000

150000

200000

250000

300000

350000

400000

450000

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

FWHM O=C-O (eV)

Sen

siti

vity

C-H

(cp

s)

Measured Spec

PET performance data


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10 eV PE FWHM = 0.68eV

40eV PE FWHM = 0.83 eV

Clear loss of chemical resolution evidenced in carbonyl peak

Effect of PE on measured data


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200 microns

800 micronsC 1s spectrum from wood fibres

Neutralization of Rough Samples

The sample of wood pulp fibres shown in the optical image to the right would traditionally be an extremely difficult sample to charge neutralize. However, as demonstrated by the excellent resolution on the C 1s spectrum poses no problem with the AXIS co-axial charge neutralizer.


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XPS Analysis of Plasma Deposited Coatings

Survey spectrum of plasma treated nylon confirming a large amount of surface F incorporation. Quantification of the XPS spectra gave 55% Fluorine on the surface.

A high resolution C 1s spectrum recorded at 10 eV pass energy demonstrates the excellent spectral resolution achieved on these irregular, highly insulating samples. The resolution allows confident identification of many of the chemical functionalities present: C-H; C-CF/C-CO2; C-CFn/C-O; C-F/C=O; CF-CFn/CO2; CF2; and CF3.


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XPS Analysis of Plasma Deposited Coatings

High resolution C 1s spectrum of wet chemical fluorosolvent treated nylon after 1 wash and 5 washes demonstrating loss of surface coating

Overlay of C 1s spectra recorded from the wet chemical fluorosolvent treated fabric before washing, after 5 washes and after 5 washes and ironing.

Wet chemical treatment

5 Washes

5 washes + ironing


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Small area analysis


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The Selected Area Aperture


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Selected Area ApertureThe selected area aperture is used to define a small analysis area at the surface. There are two approaches that may be adopted to allow XPS analysis from areas in the micron range. One approach is ti insert an aperture into the electrostatic lens column, as shown in the figures below, to forma virtual probe at the surface. An alternative approach is to use a focussed excitation source with the transfer lens collecting photoelectrons from the irradiated area. Selected area spectroscopy and mapping is descried in greater detail in technical note MO224 (available from Kratos Analytical).

110m analysis area 27m analysis area

Selected area apertures

Angle defining iris

Analyser entrance slit

Ele

ctro

stat

ic le

ns c

olum

n

Ele

ctro

stat

ic le

ns c

olum

n


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AXIS Electron Optics : Selected Area and Scanned Imaging

x

yFixed x,y voltage applied to scan plates to deflect analysis position to defined position on sample.

Scanning x,y voltage applied to scan plates to deflect analysis position over defined area of sample to generate a map.

Selected area apertures

Angle defining iris

Analyser entrance slit

Beam scanning plates, x & y

27m analysis area

Plan view of sample


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Plasma modification and Patterning

• Substrate : Polystyrene with surface modified by exposure to CFx containing plasma.

• TEM grid then used as a mask and sample reintroduced into a plasma chamber.

• Substrate and grid exposed to C-O, C-N containing plasma.

• Can pattern be observed?• What further information can be extracted from the images?

PSC-O,C-Nfunctional groups

PSCFx

functional groups


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Plasma modification and Patterning

- Large area (300x700um) survey scan from patterned area

F 1s

O 1s

N 1s

C 1s

- F 1s parallel image for 60 sec.

As the sample was a clear polymer sheet with thin plasma modified layer there was nothing to see optically.

A large area (300x700um) survey spectrum acquired from the sample showed photoelectron peaks from fluorine, oxygen, nitrogen and carbon.

A quick parallel image corresponding to the fluorine gave a well resolved grid pattern.

To better characterise the chemistry of the surface small spot spectra were acquired.


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Defining the selected area spectrum position

The parallel image is used to define the position for the small spot spectra by simply clicking with the mouse and importing the position into the acquisition software shown to the right.

The virtual probe is deflected to the defined position using the beam scanning plates.

CF3

CF2

CC,CH

CO,CN

CC,CH

CO,CN


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Imaging XPS


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The Spherical Mirror Analyser (SMA)


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Parallel Imaging Mode of AXIS Ultra

Outer hemisphere of HSA

Charge neutraliser

Spherical mirror analyser (SMA)

Hemispherical analyser (HSA)

Magnetic lensSample

Selected area aperture

Objective lens

Delayline detector

Retarding projectorlens

• Objective lens produces magnified photoelectron image I1

• Projector lens produces image I2 retards to pass energy E0

• Magnification at detector variable from <5x to >100x

• Field of view on sample from >2mm to <100m

• Lateral resolution to <2m

• Operation in FAT mode and provides energy resolution comparable to HSA.

I1

I2


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SMA and Parallel Imaging

• Fast Parallel XPS Imaging• as the sample is moved, so the photoelectron image moves.

• Lateral Resolution specification < 3 m• Fixed analyser transmission (FAT) mode

• energy resolution constant at all binding energies.• good energy resolution at all binding energies.

• ‘Real time’ chemical state XPS imaging• ability to differentiate between elements in different chemical states.


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Variable Field of View - Real Time Imaging of Au grid

2 mm fov

400 m fov

200 m fov• Au images acquired in less than 60 secs.

• Field of view (f.o.v.) changed by selecting predefined lens modes for a specific magnification. The new f.o.v. is displayed within seconds.

800 m fov 400 m fov


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XPS Imaging of 5 m Cu Bars

2.2 m edge

25m from centre of bars

After acquisition of the image a line scan can be generated. The line-scan can be processed to provide edge measurements, giving an indication of lateral resolution


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Fast real-time imaging

• Au finder grid

• Parallel images acquired in 5,10, 20 and 60 seconds

• Fast photoelectron images allow easy sample alignment

• As sample moves … image moves!!


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Large area fast parallel imaging

3.2 x 3.2mm image7um spatial resolution300 sec total acquisition time

1.6 x 1.6mm image3um spatial resolution300 sec total acquisition time


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Spectra from Images With AXIS Ultra

• The experiment requires the acquisition of a sequence of images over any energy range.• 300 - 270eV with 0.2 eV steps corresponding to C 1s region.• 30 sec per image - total acquisition 75 mins

• Sum intensity of pixels within defined area to obtain spectral information form that area

Set of images as a function of Binding Energy (eV)

x (mm)

y(m

m)

256x256 pixels

270eV

300eV


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Spectra from images

As generatedspectrum generated from significant PCA components

It is possible to use the image dataset to reconstruct a spectrum. The example below shows a spectrum generated from a single pixel (blue) using the raw images. When the noise has been removed from the image dataset using the PCA approach a much more convincing spectrum is shown.

This spectrum was defined from a single pixel 1.4 x 1.4um area ! It is possible to generate a spectrum from any of the 256 x 256 pixels on the imaged area – over 65,500 spectra !!


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Spectra from Images

C 1s spectrum generated from 5x5 pixels

CC,CH

CO

C=O

-CF2

-CF3

• After generating spectrum from images it is then possible to deconvolute the data and fit with components.

• An image may then be generated corresponding to a specific component.

– Has the advantage that peak shifts may be accommodated in by the model.

– Integrating area under the peak allows chemical state images show relative concentrations.


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Quantitative Elemental and Chemical State Imaging

CH, CC CO, CN C=O CF2

-CF3 Fluorine Nitrogen Oxygen


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Large area imaging – image stitching


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glass

ZTO (ZnSnO)

CTO (CdSnO)

CdSCdTe

Approximate thickeness / nm

2020

1000-350

1000-350

CdTe / CdS / ZTO / CTO / glass stack

XPS imaging used for film continuity


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100 m

In photoelectron image90 sec acquisition

Na photoelectron image240 sec acquisition

100 m

NREL CIGS Sample : XPS images


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1mm

1mm

In XPS image(9x4) stitch

Na XPS image(9x4) stitch

NREL CIGS Sample : XPS stitched images


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NREL CIGS Sample : XPS stitched images

Overlay of In (9x4) stitched image (red) and Na (9x4) stitched image (blue)


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Na

1s

Cu

2p

O K

LL

In M

NN

In 3

p

In 3

p

O 1

s

In 3

d

Na

KL

L

C 1

s

Se

3p

Se

LM

M

Se

3dN

a 2

s

Ga

3d /

In

4d

27um selected area XPS

100 m

defect

substrate

NREL CIGS Sample : selected area XPS


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Angle resolved XPS


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Angular Dependence of XPS

d

d ~ 8-10 nm

d

photoelectrons

X-rays

photoelectrons

X-rays


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Si wafer with native oxide

0° to sample normal

Bulk Sensitive

70° to sample normal

Surface Sensitive

Si oxide

Si Hydroxide

Si 2p1/2

Si 2p3/2

Si Bulk

Si OxideCarbon


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Native oxide on Si wafer

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60 70 80

Angle (degree)

Ato

mic

Co

nce

ntr

atio

n (

%) O 1s

C 1s

Si Oxide

Si Metal

Si wafer with native oxide

• Si sample with native oxide was not cleaned prior to analysis.

• Sample tilted from 0° through 70° with steps of 10°

• The contribution from Si oxide and Si hydroxide convoluted components have been combined.


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MEMs Depth Profile Reconstruction for Si wafer with native oxide

MEMs - Reconstructed Depth Profile

0

10

20

30

40

50

60

70

80

90

100

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Depth (nm)

Ato

mic

Co

nc

en

tra

tio

n (

%)

O 1s

C 1s

Si Oxide

Si Metal

0

20

40

60

80

100

120

0 1 2 3 4 5

Ato

mic

Co

nce

ntr

atio

n [

%]

Depth [nm]

Reconstructed depth profiles alfa =37.0392 c = 4.89436

Si MetalPrior:Si Metal


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Substrate Substrate

O

OO

OO

F

OO

O

OO

O F

OO

OO

O

OO

OO

S u b s t r a t eS u b s t r a t e

O

OO

OO

F

OO

O

OO

O F

OO

OO

O

OO

OO

Sample A – 14-F-P-11a Sample B – 14-P-F-11a

• Chemical Formula – C59H69FO10

• HF used for the removal of native oxide on Si wafer.

• Hydrogen terminated Si-surface covalently reacts with alkene chain end to form strong Si-C bonds

• Detailed studies using AFM, water contact angle and ATR-FTIR techniques have shown that the monolayer is densely packed and well ordered.

‘Banana Shaped’ SAM Molecules


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Angle vs Concentration

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80

Angle (degree)

Ato

mic

Co

nce

ntr

atio

n (

%)

F 1s

O 1s

C 1s

Si Oxide

Si Metal

Angle Vs. Concentration

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80

Angle (degree)

Ato

mic

co

nce

ntr

atio

n (

%)

F 1s

O 1s

C 1s

Si Oxide

Si Metal

Sample A – 14-F-P-11a Sample B – 14-P-F-11a

Angle vs Atomic Concentration

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 10 20 30 40 50 60 70 80

Angle (degree)

Ato

mic

Co

nce

ntr

atio

n

F 1s

Angle vs Atomic Concentration

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 10 20 30 40 50 60 70 80

Angle (degree)

Ato

mic

Co

nce

ntr

atio

n (

%)

F 1s

Substrate

O

OO

OO

F

OO

O

OO

S u b s t r a t e

O

OO

OO

F

OO

O

OO

Substrate

O F

OO

OO

O

OO

OO

S u b s t r a t e

O F

OO

OO

O

OO

OO

‘Banana Shaped’ SAM Molecules


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MEMs Reconstructed Depth Profile

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 1 2 3 4 5 6 7 8 9 10

Depth (nm)

Ato

mic

Co

nce

ntr

atio

n (

%)

F 1s * 5

O 1s

C 1s

Si Oxide

Si Metal

MEMs Depth Profile Reconstruction – Sample A

Substrate

O

OO

OO

F

OO

O

OO

S u b s t r a t e

O

OO

OO

F

OO

O

OO


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MEMs Reconstructed Depth Profile

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 1 2 3 4 5 6 7 8 9 10

Depth (nm)

Ato

mic

Co

nce

ntr

atio

n (

%)

F 1s * 5

O 1s

C 1s

Si Oxide

Si Metal

MEMs Depth Profile Reconstruction – Sample B

Substrate

O F

OO

OO

O

OO

OO

S u b s t r a t e

O F

OO

OO

O

OO

OO


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MEMs Depth Profile Reconstruction

0

2

4

6

8

10

12

14

16

0 1 2 3 4 5 6 7 8 9 10

Depth (nm)

Ato

mic

Co

nc

en

tra

tio

n (

%)

Sample A *5

Sample B *5

Substrate

O F

OO

OO

O

OO

OO

S u b s t r a t e

O F

OO

OO

O

OO

OO

Sample A

Substrate

O

OO

OO

F

OO

O

OO

S u b s t r a t e

O

OO

OO

F

OO

O

OO

Sample B

MEMs Depth Profile Reconstruction – Depth Distribution of Fluorine


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XPS depth profiling - inorganics

• Accepted standard technique for analysis of inorganic samples• Improvements in small spot XPS mean small etch craters can be

used• Etch rates in the range of 1 – 50nm min-1 (Ta2O5)

• Recent advances in ion gun technology have lead to lower primary ion energies for improved interface resolution.


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250 V

O 1s

Al 2p

F 1s

Mg 2p Si Oxide

Si Elemental

Al2O3-Mg2F-SiO2-Si 250V beam energy


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width of 1st Al layerfwhm 58nm

width of last Al layerfwhm 63nm

Multilayer sample 750 V Ar+Etch conditions: 750 V, 3 x 3 mm raster, 60 s etch cycles. Etch rate on Ta2O5: 2.3 nm/minAcquisition: 10 s snapshot spectra, cycle time 2min 50 sTotal acquisition time: ~14 hours


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surface

layer 1

layer 3

layer 5

Example of 10s Ga 2p snapshot spectra 110 µm are of analysis

Multilayer sample 750 V Ar+


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Si 2p region

Si (elemental)

Si (carbide)

Si (oxide)

Si 2p region

SiC/Si : high resolution snapshot spectra


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SiC/Si : Elemental depth profile

Oxygen

Silicon

Carbon

750 V Ar+ ions3x3mm rastered crater


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SiC/Si : Si chemical state depth profile

Si (

elem

enta

l)

Si (

carb

ide)

Si (

oxid

e)

Si (

elem

enta

l)

Si (

carb

ide)

Si (

oxid

e)

Si (

elem

enta

l)

Si (

elem

enta

l)

Si (

carb

ide)

2 41 3

1

2

3

4

Si (elemental)Si (oxide)Si (carbide)

surface

bulk

SiC/Si interface

SiC sub-surface


www.kratos.com

Auger electron spectroscopy - AES


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FE-Auger Electron Source

Field emission electron source and ion pump shown here in situ on an AXIS Ultra.


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Hi Magnification SEM with Linescan

5 microns

266 nm resolution measured using 80% - 20% line scan from SiO2 / Si sample.


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Si KLL Auger spectra

Si KLL oxide

Si KLL elemental


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Si wide scan Auger spectra


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O KLL Auger map and SEM

20 microns 20 microns


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Atmospheric corrosion of nickel SEM images

I.Odnevall & C. Leygraf J.Electrochem. Soc., vol 144, No. 10, October 1997, 3518-3525

The atmospheric corrosion of nickel in a rural atmosphere – the formation of sulfate-containingcorrosion products with a characteristic dendritic morphology.


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Atmospheric corrosion of nickel AES after light etch

X

X

S

C

O

NiNi Ni

NiNi

Ni

CO

AES spectra show the presence of sulfur in the dendritic structure only.

dendrite

substrate


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Atmospheric corrosion of nickel AES maps

S (p-b) map O (p-b) map Ni (p-b) map

The images shown are peak - background maps.


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Duplex stainless steel UNS S32750 SEM & AES

X

X

Fe

NiNi

FeFe

CrCr

C

Fe

NiNi

FeCrCr

C

Fe

The sample was etched to remove the surface oxide before the SEMand AES were acquired. There was a slight difference in the Cr intensitybetween the two areas. Cr and Ni maps were acquired to investigateany spatial differences in their concentrations.

M. Femenia, J. Panl & C. Leygraf J.Electrochem. Soc., 151, (10) B581-B585 (2004)

In duplex stainless steels the alloying elements are not uniformly distributedbetween the two phases (austenite and ferrite). For example Cr and Mo partitionto the ferrite phase and Ni and N to the austenite.

aust

enite

ferr

ite

ferr

iteaustenite - light

ferrite - dark


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Duplex stainless steel UNS S32750 AES maps

Cr p-b map Ni p-b map

The Cr concentration is highest in the ferrite where the Ni concentration is lowest (austenite). The N concentration should be highest in the austenite region. Further AES spectra, with longer acquisition times, were recorded to try and detect the low level of nitrogen present.


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SEM Image of 1 micron Au Pattern on integrated IC

An SEM image of the Au pattern was recorded using a 30 micron field of view.


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SEM Image of 1 micron Au Pattern

1 m

Line scan used to measure one of the Au lines from the SEM image


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Au MNN

Al KLL

O KLL

C KLL

Au OPP

S LMM

Al LMM

Auger Spectroscopy

Auger spectra were recorded from on one of the pads (red) and the substrate (blue)


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Back Scattered Image of 1 micron Au Pattern

Sample was then etched and a back scattered image recorded with a 10 micron field of view.


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Auger Maps

Auger maps were recorded of the Au MNN and Al KLL peaks. Images displayed below are peak minus background maps recorded using 64 x 64 pixels and 100 ms dwell time. Total time for each image was 410 seconds (820 seconds for peak and background).

Au MNN Map Al KLL Map


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Auger Maps

Overlay of Au MNN and Al KLL peak minus background maps recorded using 150 x 150 pixels and 50 ms dwell time.


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Auger Maps: 100nm spatial resolution100 nm 80/20 resolution measured across a feature in Auger mapping mode.


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Corrosion Pit: Cu on Au

An SEM image of a corrosion pit was recorded using a 400 micron field of view.


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Auger Spectroscopy

Auger spectra were recorded from in the corrosion pit (left) and the outer ring (right)

In corrosion pit Outer ring

Au MNN

Au NOO

S LMM

Cu LMM

O KLL

Cl LMM

Corrosion pit Outer ring


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Auger Maps

Au MNN Map

Cl KLL Map

Cu LMM Map

S LMM Map


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Sample 4 : Auger Maps

Overlay of Au (red), Cu (green) and Cl (blue) peak minus background Auger maps


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SEM Image of Corrosion Pit following an etch

An SEM image of a corrosion pit was recorded following an Ar ion etch


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Auger Spectroscopy of corrosion product

Auger spectrum recorded from the corrosion product

Cu LMM

O KLLCl LMM


108

Ultra Violet Photon Source

Optimized for maximum He (I) or He (II) (or Ne (l)/Ne (ll)) output.

1mm diameter guide to give a maximum lamp current of 37mA at17.5W

Minimum step size energy scale is 0.25meV in UPS mode.


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Ag EF = 95 meV.

Ag 4d reference data: UPS

>1.5MCPS


110

Ag 4d reference data: UPS

Hi (II) Ag 4d


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XPS/UPS of synthetic diamond

Optical image of synthetic diamond


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O 1s

C 1s

O KLL

XPS/UPS of DLC

Element O 1s C 1s

rel. atomic conc. 30.8 70.2


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Sample Heating

0

50

100

150

200

250

300

350

400

450

0.00 10.00 20.00 30.00 40.00 50.00 60.00

Heating time (minutes)

Tem

per

atu

re (

ºC)

Sample temperature (ºC)

Set temperature (ºC)

Sample heated to 450°C to reduce contamination

In-situ heating of DLC sample

Heating and cooling controlled directly from software


114

O 1sO KLL

Element O 1s C 1s

rel. atomic conc. (%

1.3 98.7

C KLL

Post annealing


115

Heated Diamond Sample – He (I) UPS

EO= 17.8eV

EF = 0.73eV

Φ= 21.22eV – (17.8eV – 0.73eV)

Φ= 4.15eV


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Teflon tube

Silicon containing plasma

Small area XPS and XPS imaging


117

Plasma treated polymer tube : survey spectrascanned spectra

plasma treatedend of tube

cut end of tube

Si 2

p

Si 2

s

C 1

s

N 1

s

O 1

s

F 1

s

F K

LL

O K

LL

survey spectra from 110um analysis area


118

elemental concentration line scan

0

10

20

30

40

50

60

70

0 2000 4000 6000 8000 10000 12000

distance / um

conc

entr

atio

n (r

elat

ive

at. %

)

F 1s

O 1s

N 1s

C 1s

Si 2p

Concentration line scan by 110um, classic small area analysis

Several mm’s

Plasma


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Plasma treated polymer tube : high resolution spectrascanned spectra

N 1s region Si 2p1s region


cut end of tube


cut end of tube

C 1s region


cut end of tube


cut end of tube


120

Carbon chemical state line scan

0

10

20

30

40

50

60

70

0 2000 4000 6000 8000 10000 12000

distance / um

rela

tive

co

nce

ntr

atio

n (

%)

C 1s CC,CH

C 1s C-O/CN

C 1s CF/C=O

C 1s CF2

C 1s CF3

CC

,CH

C-O

/C-N

C=

O/C

FC

F2

CF

3

CC

,CH

C-O

/C-N

C=

O/C

FC

F2

CF

3

CC

,CH

C-O

/C-N

C=

O/C

F

CF

2

CF

3

CC

,CH

C-O

/C-N

C=

O/C

F

CF

2

CF

3

plasma treated end

bulk polymer end

representative C 1s spectra as a function of position from the end of the tube

Plasma treated polymer tube : high resolution spectra


121

Plasma treated polymer tube : Chemical state images

CC,CH (peak-background)parallel image at 285eV120 sec acquisition

CF2 (peak-background)parallel image at 292eV120 sec acquisition

overlay of CC,CH (red) with CF2 (green) parallel images


122

Plasma treated polymer tube : elemental images800 m2 field of view

CF2 (peak-background) F 1s (peak-background)120 sec acquisition 60 sec acquisition


123

Plasma treated polymer tube : chemical state & elemental images400 m2 field of view

CC,CH (peak-background)parallel image at 285eV180 sec acquisition

CF2 (peak-background)parallel image at 292eV180 sec acquisition

F 1s (peak-background)parallel image at 689eV90 sec acquisition


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55um analysis areap1 (substrate)

55um analysis areap2 (plasma polymer)

F 1s

O 1s

N 1s

C 1s

Si 2pSi 2s

F 1s

O 1sN 1s

C 1s

Si 2pSi 2s

Plasma treated polymer tube : selected area spectroscopy400 m2 field of view

Analysis position Atomic Concn %

Fluorine Oxygen Nitrogen Carbon Silicon

Point 1 45.87 4.66 1.74 45.34 2.39

Point 2 27.33 9.87 6.11 50.07 6.72


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Plasma treated polymer tube : selected area spectroscopy400 m2 field of view

2

1

55um analysis point 1

55um analysis point 2

F-S

i (in

orga

nic)

C-F

2 -

org

anic

CC

,CH

C-O

/C-N

C=

O/C

F

CF

2

CF

3


126

F 1s image 30 sec per image

Total acquisition time 5 mins

open, plasma treated end cut end of tube

Stitched images - 12 x 800 m2 field of view

Si concentration F concentration


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Value can be added to XPS images by the use of multivariate analysis methods

Here a disc shape specimen of ASTM F 138 stainless steel, shown in the optical image above was machined, electropolished and laser marked. The area of interest is shown in the expanded view with the blue box indicting the area imaged with XPS.

Quantitative imaging and multivariate analysis


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Printed using CasaXPS

Summed pixels (raw data)

x 10-2

14

16

18

20

22

24

26

28

30

32

CPS

720 718 716 714 712 710 708 706 704 702 700 698Binding Energy (eV)

Medical grade stainless steel Fe 2p images

Sum of pixels(raw data)

binding energy

Fe 2p images719eV 710eV (oxide) 706.5eV (metal) 700eV background

Fe 2p3/2

Acquire

Fe 2p3/2 multi-spectral images 720-698eV, 0.25eV steps, 30 s per image

Cr 2p multi-spectral images, 0.25eV steps, 30 s per image


129

Acquire

Fe 2p3/2 multi-spectral images 720-698eV, 0.25eV steps, 30 s per image

Cr 2p multi-spectral images, 0.25eV steps, 30 s per image

Process:

Convert image dataset to 256 x 256 spectra at a pixel

SVD sort / reduced PCA to order AF’s

Construct images from the first 2 abstract factors

(1) Mean AF (2) Maximum variance

(3) (4)

Fe 2p3/2 region abstract factors


130

Raw & SVD/reduced PCA processed data


Pr:Fe/1

x 10-2

14

16

18

20

22

24

26

28

30

32

CP

S


Raw data

SVD/reduced PCA processed

Summed pixel intensity from 256x256 pixels


Fe/1

x 10-2

16

18

20

22

24

26

28

30

CP

S



Fe/1

x 10-2

18

20

22

24

26

28

30

32

34

36

38

CP

S


Fit components to processed data corresponding to Fe oxide and Fe metal

Single pixel spectrum from metallic regionSingle pixel spectrum from oxide region


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Quantitative Cr and Fe images

• Cr image (red) shows enhanced concentration at the edge of the laser marked area

• Cr rich region at ‘corrosion front’• Fe metal (green) across entire sample but much lower concentration on laser

marked area• oxide layer thicker in laser marked area attenuates the Fe metallic

signal

Chromium relative atomic concentration image

Iron (metal) relative atomic concentration image


132

Fe 2p 3/2

METALFe 2p 3/2

OXIDE

False colour range used to assign pixels

Raw pixels then summed to give “true” spectra from oxide and metal region

Pixel grouping


133

Image stitching – high spatial resolution over large image areas

glass slide

poly(hydroxyethyl methacrylate)(pHEMA)

Acrylate, diacrylate, dimethylacrylate and triacrylate

combinations (as above)

D.G. Anderson, S. Levenberg & R. Langer Nature Biotechnology 22 (7) 863-866

Monomers used to generate sample array

1:40pm BO+PS+AS+SS TuA1 Room 201

“High throughput surface chemical analysis of polymer microarrays: Wettability, protein adsorption and cell response”


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Quantitative elemental stitched images

2mm 2mm 2mm

Fluorine (peak-background) Oxygen (peak-background) Carbon (peak-background)

● Quantitative elemental images corrected for transmission function and RSF● Thermal scale now indicates relative atomic concentration at a pixel

- each pixel represents 6.25um on the surface


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Quantitative elemental stitched images

Fluorine11.4 at%

0 at%

90.6 at% 60.8 at%Carbon

Oxygen32.5 at%

7.1 at%

2mm


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10 reasons why Axis Ultra is best selling XPS

• Only instrument to offer 0.48eV @ 400,000CPS• Excellent performance on insulators < 0.68eV PET• Largest analyser 165mm radius• DLD – pulse counting quantitative parallel imaging• DLD – snapshot mode 128 data channels• Fully automated control of all spot sizes• Electron only charge neutralisation system• Smallest analysis area 15um• Two analysers optimised for imaging and spectroscopy• Electrostatic deflection system for small area spectroscopy

A Shimadzu Group Company Kratos AXIS Ultra DLD The small spot, parallel imaging, multi-technique...

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Transcript of A Shimadzu Group Company Kratos AXIS Ultra DLD The small spot, parallel imaging, multi-technique...