SlideShare ist ein Scribd-Unternehmen logo
1 von 52
X-ray Photoelectron Spectroscopy (XPS)
Surface Analysis The Study of the Outer-Most Layers of Materials (<100   ). ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Introduction to  X-ray Photoelectron Spectroscopy (XPS)
Introduction to X-ray Photoelectron Spectroscopy (XPS) ,[object Object],[object Object],[object Object],[object Object]
What is XPS? X-ray Photoelectron  Spectroscopy (XPS), also known as Electron Spectroscopy for Chemical Analysis (ESCA) is a widely used technique to investigate the chemical composition of  surfaces.
What is XPS? X-ray Photoelectron spectroscopy, based on the photoelectric effect, 1,2  was developed in the mid-1960’s by Kai Siegbahn and his research group at the University of Uppsala, Sweden. 3 1. H. Hertz, Ann. Physik 31,983 (1887). 2. A. Einstein, Ann. Physik  17,132 (1905). 1921 Nobel Prize in Physics. 3. K. Siegbahn, Et. Al.,Nova Acta Regiae Soc.Sci., Ser. IV, Vol. 20 (1967). 1981 Nobel Prize in Physics.
X-ray Photoelectron Spectroscopy Small Area Detection X-ray Beam X-ray penetration depth ~1  m. Electrons can be excited in this entire volume. X-ray excitation area ~1x1 cm 2 .  Electrons are emitted from this entire area Electrons are extracted only from a narrow solid angle. 1 mm 2 10 nm
The Photoelectric Process ,[object Object],[object Object],[object Object],[object Object],Conduction Band Valence Band L2,L3 L1 K Fermi Level Free  Electron  Level Incident X-ray Ejected Photoelectron 1s 2s 2p
Auger Relation of Core Hole ,[object Object],[object Object],[object Object],[object Object],Conduction Band Valence Band L2,L3 L1 K Fermi Level Free  Electron  Level Emitted Auger Electron 1s 2s 2p
XPS Energy Scale ,[object Object]
XPS Energy Scale- Kinetic energy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
XPS Energy Scale- Binding energy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Fermi Level Referencing Free electrons (those giving rise to conductivity) find an equal potential which is constant throughout the material. Fermi-Dirac Statistics: f(E) =  1 exp[(E-E f )/kT] + 1 1.0 f(E) 0 0.5 E f 1.  At T=0 K: f(E)=1 for E<E f f(E)=0 for E>E f 2.  At kT<<E f  (at room temperature kT=0.025 eV) f(E)=0.5 for E=E f T=0 K kT<<E f
Fermi Level Referencing
Sample/Spectrometer Energy Level Diagram- Conducting Sample hv Because the Fermi levels of the sample and spectrometer are aligned, we only need to know the spectrometer work function,   spec , to calculate BE(1s).  E 1s Sample Spectrometer e - Free Electron Energy Fermi Level, E f Vacuum Level, E v  sample KE(1s) KE(1s)  spec BE(1s)
Sample/Spectrometer Energy Level Diagram- Insulating Sample hv A relative build-up of  electrons at the spectrometer raises the Fermi level of the spectrometer relative to the sample.  A potential E ch  will develop. E 1s Sample Spectrometer e - Free Electron Energy BE(1s) Fermi Level, E f Vacuum Level, E v KE(1s)  spec E ch
Binding Energy Referencing ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
Where do Binding Energy Shifts Come From? -or How Can We Identify Elements and Compounds? Electron-electron  repulsion Electron-nucleus  attraction Electron Nucleus Binding Energy Pure Element Electron-Nucleus Separation Fermi Level Look for changes here by observing electron binding energies
Elemental  Shifts
Elemental Shifts
Binding Energy Determination The photoelectron’s binding energy will be based on the element’s final-state configuration. Conduction Band Valence Band Fermi Level Free  Electon  Level Conduction Band Valence Band 1s 2s 2p Initial State Final State
Chemical Shifts-  Electronegativity Effects Carbon-Oxygen Bond Valence Level C 2p Core Level C 1s Carbon Nucleus Oxygen Atom C 1s  Binding Energy Electron-oxygen atom attraction (Oxygen Electro-negativity) Electron-nucleus  attraction (Loss of  Electronic Screening) Shift to higher binding energy
Chemical Shifts- Electronegativity Effects
Electronic Effects Spin-Orbit Coupling
Electronic Effects Spin-Orbit Coupling
Electronic Effects Spin-Orbit Coupling
Electronic Effects Spin-OrbitCoupling
Electronic Effects- Spin-Orbit Coupling Ti Metal Ti Oxide
Electron Scattering Effects   Energy Loss Peaks Photoelectrons travelling through the solid can interact with other electrons in the material.  These interactions can result in the photoelectron exciting an electronic transition, thus losing some of its energy (inelastic scattering). e ph   +  e solid   e* ph   + e** solid
Electron Scattering Effects Plasmon Loss Peak
Electron Scattering Effects Plasmon Loss Peak
Quantitative Analysis by XPS For a Homogeneous sample: I = N  DJL  AT where: N = atoms/cm 3  = photoelectric cross-section, cm 2 D = detector efficiency J = X-ray flux, photon/cm 2 -sec L = orbital symmetry factor    = inelastic electron mean-free path, cm A = analysis area, cm 2 T = analyzer transmission efficiency
Quantitative Analysis by XPS N = I/  DJL  AT Let denominator = elemental sensitivity factor, S N = I / S Can describe Relative Concentration of observed elements as a number fraction by: C x  = N x  /   N i C x  = I x /S x  /   I i /S i The values of S are based on empirical data.
Relative Sensitivities of the Elements 1s 2p 3d 4d 4f
XPS of Copper-Nickel alloy
Comparison of Sensitivities
Instrumentation for X-ray Photoelectron Spectroscopy
Introduction to X-ray Photoelectron Spectroscopy (XPS) ,[object Object],[object Object],[object Object],[object Object]
Instrumentation for XPS Surface analysis by XPS requires irradiating a solid in an Ultra-high Vacuum (UHV) chamber with monoenergetic soft X-rays and analyzing the energies of the emitted electrons.
Why UHV for Surface Analysis? ,[object Object],[object Object],[object Object],[object Object],Degree of Vacuum 10 10 10 10 10 2 -1 -4 -8 -11 Low Vacuum Medium Vacuum High Vacuum Ultra-High Vacuum Pressure Torr
X-ray Photoelectron Spectrometer
X-ray Photoelectron Spectrometer X-ray Source Electron Optics Hemispherical Energy Analyzer Position Sensitive Detector (PSD) Magnetic  Shield Outer Sphere Inner Sphere Sample Computer System Analyzer Control Multi-Channel Plate Electron Multiplier Resistive Anode Encoder Lenses for Energy Adjustment (Retardation) Lenses for Analysis Area Definition Position Computer Position Address Converter
X-ray Generation Conduction Band Valence Band 1s 2s 2p Conduction Band Valence Band L2,L3 L1 K Fermi Level Free  Electron  Level 1s 2s 2p Secondary electron Incident  electron X-ray Photon
Relative Probabilities of Relaxation of a K Shell Core Hole Note: The light elements have a low cross section for X-ray emission.   Auger  Electron Emission X-ray Photon Emission
Schematic of Dual Anode X-ray Source Anode Fence Anode 1 Anode 2 Filament 1 Filament 2 Fence Cooling Water Cooling Water Water Outlet Water Inlet Anode Assembly Filament 1 Anode 1 Fence Filament 2 Anode 2
Schematic of X-ray Monochromator Sample X-ray Anode Energy  Analyzer Quartz  Crystal Disperser Rowland Circle e -
Applications of  X-ray Photoelectron Spectroscopy (XPS)
XPS Analysis of Pigment from Mummy Artwork 150 145 140 135 130 Binding Energy (eV) PbO 2 Pb 3 O 4 500 400 300 200 100 0 Binding Energy (eV) O Pb Pb Pb N Ca C Na Cl XPS analysis showed that the pigment used on the mummy wrapping was Pb 3 O 4  rather than Fe 2 O 3 Egyptian Mummy  2nd Century AD World Heritage Museum University of Illinois
Analysis of Carbon Fiber- Polymer Composite Material by XPS Woven carbon fiber composite XPS analysis identifies the functional groups present on composite surface.  Chemical nature of fiber-polymer interface will influence its properties. -C-C- -C-O -C=O
Analysis of Materials for Solar Energy Collection by XPS Depth Profiling-   The  amorphous-SiC/SnO 2  Interface The profile indicates a reduction of the SnO 2  occurred at the interface during deposition.  Such a reduction would effect the collector’s efficiency. Photo-voltaic Collector Conductive Oxide- SnO 2 p-type a-SiC a-Si Solar Energy SnO 2 Sn Depth 500 496 492 488 484 480 Binding Energy, eV Data courtesy A. Nurrudin and J. Abelson, University of Illinois
Angle-resolved XPS  =15°  = 90° More Surface Sensitive Less Surface Sensitive Information depth = dsin  d = Escape depth ~ 3    = Emission angle relative to surface  =  Inelastic Mean Free Path  
Angle-resolved XPS Analysis of Self-Assembling Monolayers ,[object Object],[object Object],[object Object],Data courtesy L. Ge, R. Haasch and A. Gewirth, University of Illinois

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Cyclic Voltametery
Cyclic VoltameteryCyclic Voltametery
Cyclic Voltametery
 
I. Electronic properties of nanomaterials
I. Electronic properties of nanomaterialsI. Electronic properties of nanomaterials
I. Electronic properties of nanomaterials
 
X ray photoelecton spectroscopy
X ray photoelecton spectroscopy X ray photoelecton spectroscopy
X ray photoelecton spectroscopy
 
Electron Spin Resonance Spectroscopy(ESR) OR Pulse Magnetic Resonance Spectro...
Electron Spin Resonance Spectroscopy(ESR) OR Pulse Magnetic Resonance Spectro...Electron Spin Resonance Spectroscopy(ESR) OR Pulse Magnetic Resonance Spectro...
Electron Spin Resonance Spectroscopy(ESR) OR Pulse Magnetic Resonance Spectro...
 
X ray Photoelectron spectroscopy (XPS)
X ray Photoelectron spectroscopy (XPS)X ray Photoelectron spectroscopy (XPS)
X ray Photoelectron spectroscopy (XPS)
 
Instrumentation presentation - Auger Electron Spectroscopy (AES)
Instrumentation presentation - Auger Electron Spectroscopy (AES)Instrumentation presentation - Auger Electron Spectroscopy (AES)
Instrumentation presentation - Auger Electron Spectroscopy (AES)
 
Auger Electron Spectroscopy
Auger Electron SpectroscopyAuger Electron Spectroscopy
Auger Electron Spectroscopy
 
Cyclic voltammetry
Cyclic voltammetryCyclic voltammetry
Cyclic voltammetry
 
Electron diffraction and Neutron diffraction
Electron diffraction and Neutron diffractionElectron diffraction and Neutron diffraction
Electron diffraction and Neutron diffraction
 
Optical band gap measurement by diffuse reflectance spectroscopy (drs)
Optical band gap measurement by diffuse reflectance spectroscopy (drs)Optical band gap measurement by diffuse reflectance spectroscopy (drs)
Optical band gap measurement by diffuse reflectance spectroscopy (drs)
 
AUGER & ESCA Spectroscopy( Mass Spectroscopy )
AUGER & ESCA Spectroscopy( Mass Spectroscopy )AUGER & ESCA Spectroscopy( Mass Spectroscopy )
AUGER & ESCA Spectroscopy( Mass Spectroscopy )
 
Cyclic Voltammetry: Principle, Instrumentation & Applications
Cyclic Voltammetry: Principle, Instrumentation & ApplicationsCyclic Voltammetry: Principle, Instrumentation & Applications
Cyclic Voltammetry: Principle, Instrumentation & Applications
 
Surface and Materials Analysis Techniques
Surface and Materials Analysis TechniquesSurface and Materials Analysis Techniques
Surface and Materials Analysis Techniques
 
Surface enhanced raman spectroscopy, rahutosh ranjan
Surface enhanced raman spectroscopy, rahutosh ranjanSurface enhanced raman spectroscopy, rahutosh ranjan
Surface enhanced raman spectroscopy, rahutosh ranjan
 
auger electron spectroscopy (AES)
auger electron spectroscopy  (AES)auger electron spectroscopy  (AES)
auger electron spectroscopy (AES)
 
Cyclic Voltammetry Application
Cyclic Voltammetry  Application Cyclic Voltammetry  Application
Cyclic Voltammetry Application
 
Energy Dispersive Spectroscopy
Energy Dispersive SpectroscopyEnergy Dispersive Spectroscopy
Energy Dispersive Spectroscopy
 
Characterization techniques
Characterization techniquesCharacterization techniques
Characterization techniques
 
Hydrothermal &amp;solvothermal methods jeyakiruba
Hydrothermal &amp;solvothermal methods jeyakirubaHydrothermal &amp;solvothermal methods jeyakiruba
Hydrothermal &amp;solvothermal methods jeyakiruba
 
Xps - X-Ray Photoelectron Spectroscopy
Xps - X-Ray Photoelectron SpectroscopyXps - X-Ray Photoelectron Spectroscopy
Xps - X-Ray Photoelectron Spectroscopy
 

Andere mochten auch

My visit to auckland university (Ethan van Wijk)
My visit to auckland university (Ethan van Wijk)My visit to auckland university (Ethan van Wijk)
My visit to auckland university (Ethan van Wijk)
willowbank
 
A presentation ,analytical methods-for-determination-of-metals-in-environment...
A presentation ,analytical methods-for-determination-of-metals-in-environment...A presentation ,analytical methods-for-determination-of-metals-in-environment...
A presentation ,analytical methods-for-determination-of-metals-in-environment...
Adnan Sohail
 
Proton Induced X Ray Emission P P
Proton  Induced  X  Ray  Emission  P PProton  Induced  X  Ray  Emission  P P
Proton Induced X Ray Emission P P
guest123ae0
 

Andere mochten auch (14)

X-ray Photoelectron Spectrocopy (XPS)
X-ray Photoelectron Spectrocopy (XPS)X-ray Photoelectron Spectrocopy (XPS)
X-ray Photoelectron Spectrocopy (XPS)
 
Auger effect. puplic
Auger effect. puplicAuger effect. puplic
Auger effect. puplic
 
Scanning Electron Microscope- Energy - Dispersive X -Ray Microanalysis (Sem E...
Scanning Electron Microscope- Energy - Dispersive X -Ray Microanalysis (Sem E...Scanning Electron Microscope- Energy - Dispersive X -Ray Microanalysis (Sem E...
Scanning Electron Microscope- Energy - Dispersive X -Ray Microanalysis (Sem E...
 
Slade share
Slade shareSlade share
Slade share
 
My visit to auckland university (Ethan van Wijk)
My visit to auckland university (Ethan van Wijk)My visit to auckland university (Ethan van Wijk)
My visit to auckland university (Ethan van Wijk)
 
جستجو پیشرفته منابع علمی | ویژه دانشجویان شیمی
جستجو پیشرفته منابع علمی | ویژه دانشجویان شیمیجستجو پیشرفته منابع علمی | ویژه دانشجویان شیمی
جستجو پیشرفته منابع علمی | ویژه دانشجویان شیمی
 
Ppt
PptPpt
Ppt
 
2. x ray emission
2. x ray emission2. x ray emission
2. x ray emission
 
A presentation ,analytical methods-for-determination-of-metals-in-environment...
A presentation ,analytical methods-for-determination-of-metals-in-environment...A presentation ,analytical methods-for-determination-of-metals-in-environment...
A presentation ,analytical methods-for-determination-of-metals-in-environment...
 
Presentation of iqra malik
Presentation of iqra malikPresentation of iqra malik
Presentation of iqra malik
 
Unit2 Presentation
Unit2 PresentationUnit2 Presentation
Unit2 Presentation
 
Proton Induced X Ray Emission P P
Proton  Induced  X  Ray  Emission  P PProton  Induced  X  Ray  Emission  P P
Proton Induced X Ray Emission P P
 
X ray photoelectron spectroscopy (xps)
X ray photoelectron spectroscopy (xps)X ray photoelectron spectroscopy (xps)
X ray photoelectron spectroscopy (xps)
 
Materials Characterization Technique Lecture Notes
Materials Characterization Technique Lecture NotesMaterials Characterization Technique Lecture Notes
Materials Characterization Technique Lecture Notes
 

Ähnlich wie Xps

xpspresentation-180225211042 (1).pptx
xpspresentation-180225211042 (1).pptxxpspresentation-180225211042 (1).pptx
xpspresentation-180225211042 (1).pptx
AshikBabu10
 
x-ray_photoelectron_spectroscopy_(xps).ppt
x-ray_photoelectron_spectroscopy_(xps).pptx-ray_photoelectron_spectroscopy_(xps).ppt
x-ray_photoelectron_spectroscopy_(xps).ppt
asdasasds
 

Ähnlich wie Xps (20)

X ray photoelectron spectroscopy (xps)
X ray photoelectron spectroscopy (xps)X ray photoelectron spectroscopy (xps)
X ray photoelectron spectroscopy (xps)
 
Photo Electron Spectroscopy
Photo Electron SpectroscopyPhoto Electron Spectroscopy
Photo Electron Spectroscopy
 
XPSPPT useful for the students and materials reasearchers
XPSPPT useful for the students and materials reasearchersXPSPPT useful for the students and materials reasearchers
XPSPPT useful for the students and materials reasearchers
 
Characterization of materials lec 26 29
Characterization of materials  lec 26 29Characterization of materials  lec 26 29
Characterization of materials lec 26 29
 
BUSHRA NAVEED.pdf
BUSHRA NAVEED.pdfBUSHRA NAVEED.pdf
BUSHRA NAVEED.pdf
 
xpspresentation-180225211042 (1).pptx
xpspresentation-180225211042 (1).pptxxpspresentation-180225211042 (1).pptx
xpspresentation-180225211042 (1).pptx
 
X_ray_sem2.
X_ray_sem2.X_ray_sem2.
X_ray_sem2.
 
x-ray_photoelectron_spectroscopy_(xps).ppt
x-ray_photoelectron_spectroscopy_(xps).pptx-ray_photoelectron_spectroscopy_(xps).ppt
x-ray_photoelectron_spectroscopy_(xps).ppt
 
XPS.ppt
XPS.pptXPS.ppt
XPS.ppt
 
Characterization of materials lec2
Characterization of materials  lec2Characterization of materials  lec2
Characterization of materials lec2
 
x-ray photoelectron spectroscopy
x-ray photoelectron spectroscopyx-ray photoelectron spectroscopy
x-ray photoelectron spectroscopy
 
X-Ray Photoelectron Spectroscopy (XPS).pptx
X-Ray Photoelectron Spectroscopy (XPS).pptxX-Ray Photoelectron Spectroscopy (XPS).pptx
X-Ray Photoelectron Spectroscopy (XPS).pptx
 
4. XPS.pptx
4. XPS.pptx4. XPS.pptx
4. XPS.pptx
 
Electron spectroscopy
Electron spectroscopyElectron spectroscopy
Electron spectroscopy
 
X-RAY PHOTOELECTRON SPECTROSCOPY AND ELECTRON SPIN RESONANCE
X-RAY PHOTOELECTRON SPECTROSCOPY AND ELECTRON SPIN RESONANCEX-RAY PHOTOELECTRON SPECTROSCOPY AND ELECTRON SPIN RESONANCE
X-RAY PHOTOELECTRON SPECTROSCOPY AND ELECTRON SPIN RESONANCE
 
Electron microscopy 2
Electron microscopy 2Electron microscopy 2
Electron microscopy 2
 
Scanning Electron Microscope
Scanning Electron MicroscopeScanning Electron Microscope
Scanning Electron Microscope
 
Microprobing with electrons
Microprobing with electronsMicroprobing with electrons
Microprobing with electrons
 
New microsoft office word document
New microsoft office word documentNew microsoft office word document
New microsoft office word document
 
X-RayTechnology.ppt
X-RayTechnology.pptX-RayTechnology.ppt
X-RayTechnology.ppt
 

Kürzlich hochgeladen

Why Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire businessWhy Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire business
panagenda
 
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
?#DUbAI#??##{{(☎️+971_581248768%)**%*]'#abortion pills for sale in dubai@
 
Architecting Cloud Native Applications
Architecting Cloud Native ApplicationsArchitecting Cloud Native Applications
Architecting Cloud Native Applications
WSO2
 
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers:  A Deep Dive into Serverless Spatial Data and FMECloud Frontiers:  A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Safe Software
 

Kürzlich hochgeladen (20)

DBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor PresentationDBX First Quarter 2024 Investor Presentation
DBX First Quarter 2024 Investor Presentation
 
Why Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire businessWhy Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire business
 
Strategies for Unlocking Knowledge Management in Microsoft 365 in the Copilot...
Strategies for Unlocking Knowledge Management in Microsoft 365 in the Copilot...Strategies for Unlocking Knowledge Management in Microsoft 365 in the Copilot...
Strategies for Unlocking Knowledge Management in Microsoft 365 in the Copilot...
 
ICT role in 21st century education and its challenges
ICT role in 21st century education and its challengesICT role in 21st century education and its challenges
ICT role in 21st century education and its challenges
 
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
+971581248768>> SAFE AND ORIGINAL ABORTION PILLS FOR SALE IN DUBAI AND ABUDHA...
 
FWD Group - Insurer Innovation Award 2024
FWD Group - Insurer Innovation Award 2024FWD Group - Insurer Innovation Award 2024
FWD Group - Insurer Innovation Award 2024
 
Manulife - Insurer Transformation Award 2024
Manulife - Insurer Transformation Award 2024Manulife - Insurer Transformation Award 2024
Manulife - Insurer Transformation Award 2024
 
Real Time Object Detection Using Open CV
Real Time Object Detection Using Open CVReal Time Object Detection Using Open CV
Real Time Object Detection Using Open CV
 
TrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
TrustArc Webinar - Unlock the Power of AI-Driven Data DiscoveryTrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
TrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
 
AXA XL - Insurer Innovation Award Americas 2024
AXA XL - Insurer Innovation Award Americas 2024AXA XL - Insurer Innovation Award Americas 2024
AXA XL - Insurer Innovation Award Americas 2024
 
A Year of the Servo Reboot: Where Are We Now?
A Year of the Servo Reboot: Where Are We Now?A Year of the Servo Reboot: Where Are We Now?
A Year of the Servo Reboot: Where Are We Now?
 
Corporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptxCorporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptx
 
Apidays Singapore 2024 - Building Digital Trust in a Digital Economy by Veron...
Apidays Singapore 2024 - Building Digital Trust in a Digital Economy by Veron...Apidays Singapore 2024 - Building Digital Trust in a Digital Economy by Veron...
Apidays Singapore 2024 - Building Digital Trust in a Digital Economy by Veron...
 
Architecting Cloud Native Applications
Architecting Cloud Native ApplicationsArchitecting Cloud Native Applications
Architecting Cloud Native Applications
 
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
Strategize a Smooth Tenant-to-tenant Migration and Copilot TakeoffStrategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
 
Apidays Singapore 2024 - Scalable LLM APIs for AI and Generative AI Applicati...
Apidays Singapore 2024 - Scalable LLM APIs for AI and Generative AI Applicati...Apidays Singapore 2024 - Scalable LLM APIs for AI and Generative AI Applicati...
Apidays Singapore 2024 - Scalable LLM APIs for AI and Generative AI Applicati...
 
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers:  A Deep Dive into Serverless Spatial Data and FMECloud Frontiers:  A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
 
GenAI Risks & Security Meetup 01052024.pdf
GenAI Risks & Security Meetup 01052024.pdfGenAI Risks & Security Meetup 01052024.pdf
GenAI Risks & Security Meetup 01052024.pdf
 
Artificial Intelligence Chap.5 : Uncertainty
Artificial Intelligence Chap.5 : UncertaintyArtificial Intelligence Chap.5 : Uncertainty
Artificial Intelligence Chap.5 : Uncertainty
 
ProductAnonymous-April2024-WinProductDiscovery-MelissaKlemke
ProductAnonymous-April2024-WinProductDiscovery-MelissaKlemkeProductAnonymous-April2024-WinProductDiscovery-MelissaKlemke
ProductAnonymous-April2024-WinProductDiscovery-MelissaKlemke
 

Xps

  • 2.
  • 3. Introduction to X-ray Photoelectron Spectroscopy (XPS)
  • 4.
  • 5. What is XPS? X-ray Photoelectron Spectroscopy (XPS), also known as Electron Spectroscopy for Chemical Analysis (ESCA) is a widely used technique to investigate the chemical composition of surfaces.
  • 6. What is XPS? X-ray Photoelectron spectroscopy, based on the photoelectric effect, 1,2 was developed in the mid-1960’s by Kai Siegbahn and his research group at the University of Uppsala, Sweden. 3 1. H. Hertz, Ann. Physik 31,983 (1887). 2. A. Einstein, Ann. Physik 17,132 (1905). 1921 Nobel Prize in Physics. 3. K. Siegbahn, Et. Al.,Nova Acta Regiae Soc.Sci., Ser. IV, Vol. 20 (1967). 1981 Nobel Prize in Physics.
  • 7. X-ray Photoelectron Spectroscopy Small Area Detection X-ray Beam X-ray penetration depth ~1  m. Electrons can be excited in this entire volume. X-ray excitation area ~1x1 cm 2 . Electrons are emitted from this entire area Electrons are extracted only from a narrow solid angle. 1 mm 2 10 nm
  • 8.
  • 9.
  • 10.
  • 11.
  • 12.
  • 13. Fermi Level Referencing Free electrons (those giving rise to conductivity) find an equal potential which is constant throughout the material. Fermi-Dirac Statistics: f(E) = 1 exp[(E-E f )/kT] + 1 1.0 f(E) 0 0.5 E f 1. At T=0 K: f(E)=1 for E<E f f(E)=0 for E>E f 2. At kT<<E f (at room temperature kT=0.025 eV) f(E)=0.5 for E=E f T=0 K kT<<E f
  • 15. Sample/Spectrometer Energy Level Diagram- Conducting Sample hv Because the Fermi levels of the sample and spectrometer are aligned, we only need to know the spectrometer work function,  spec , to calculate BE(1s). E 1s Sample Spectrometer e - Free Electron Energy Fermi Level, E f Vacuum Level, E v  sample KE(1s) KE(1s)  spec BE(1s)
  • 16. Sample/Spectrometer Energy Level Diagram- Insulating Sample hv A relative build-up of electrons at the spectrometer raises the Fermi level of the spectrometer relative to the sample. A potential E ch will develop. E 1s Sample Spectrometer e - Free Electron Energy BE(1s) Fermi Level, E f Vacuum Level, E v KE(1s)  spec E ch
  • 17.
  • 18. Where do Binding Energy Shifts Come From? -or How Can We Identify Elements and Compounds? Electron-electron repulsion Electron-nucleus attraction Electron Nucleus Binding Energy Pure Element Electron-Nucleus Separation Fermi Level Look for changes here by observing electron binding energies
  • 21. Binding Energy Determination The photoelectron’s binding energy will be based on the element’s final-state configuration. Conduction Band Valence Band Fermi Level Free Electon Level Conduction Band Valence Band 1s 2s 2p Initial State Final State
  • 22. Chemical Shifts- Electronegativity Effects Carbon-Oxygen Bond Valence Level C 2p Core Level C 1s Carbon Nucleus Oxygen Atom C 1s Binding Energy Electron-oxygen atom attraction (Oxygen Electro-negativity) Electron-nucleus attraction (Loss of Electronic Screening) Shift to higher binding energy
  • 28. Electronic Effects- Spin-Orbit Coupling Ti Metal Ti Oxide
  • 29. Electron Scattering Effects Energy Loss Peaks Photoelectrons travelling through the solid can interact with other electrons in the material. These interactions can result in the photoelectron exciting an electronic transition, thus losing some of its energy (inelastic scattering). e ph + e solid e* ph + e** solid
  • 30. Electron Scattering Effects Plasmon Loss Peak
  • 31. Electron Scattering Effects Plasmon Loss Peak
  • 32. Quantitative Analysis by XPS For a Homogeneous sample: I = N  DJL  AT where: N = atoms/cm 3  = photoelectric cross-section, cm 2 D = detector efficiency J = X-ray flux, photon/cm 2 -sec L = orbital symmetry factor  = inelastic electron mean-free path, cm A = analysis area, cm 2 T = analyzer transmission efficiency
  • 33. Quantitative Analysis by XPS N = I/  DJL  AT Let denominator = elemental sensitivity factor, S N = I / S Can describe Relative Concentration of observed elements as a number fraction by: C x = N x /  N i C x = I x /S x /  I i /S i The values of S are based on empirical data.
  • 34. Relative Sensitivities of the Elements 1s 2p 3d 4d 4f
  • 37. Instrumentation for X-ray Photoelectron Spectroscopy
  • 38.
  • 39. Instrumentation for XPS Surface analysis by XPS requires irradiating a solid in an Ultra-high Vacuum (UHV) chamber with monoenergetic soft X-rays and analyzing the energies of the emitted electrons.
  • 40.
  • 42. X-ray Photoelectron Spectrometer X-ray Source Electron Optics Hemispherical Energy Analyzer Position Sensitive Detector (PSD) Magnetic Shield Outer Sphere Inner Sphere Sample Computer System Analyzer Control Multi-Channel Plate Electron Multiplier Resistive Anode Encoder Lenses for Energy Adjustment (Retardation) Lenses for Analysis Area Definition Position Computer Position Address Converter
  • 43. X-ray Generation Conduction Band Valence Band 1s 2s 2p Conduction Band Valence Band L2,L3 L1 K Fermi Level Free Electron Level 1s 2s 2p Secondary electron Incident electron X-ray Photon
  • 44. Relative Probabilities of Relaxation of a K Shell Core Hole Note: The light elements have a low cross section for X-ray emission. Auger Electron Emission X-ray Photon Emission
  • 45. Schematic of Dual Anode X-ray Source Anode Fence Anode 1 Anode 2 Filament 1 Filament 2 Fence Cooling Water Cooling Water Water Outlet Water Inlet Anode Assembly Filament 1 Anode 1 Fence Filament 2 Anode 2
  • 46. Schematic of X-ray Monochromator Sample X-ray Anode Energy Analyzer Quartz Crystal Disperser Rowland Circle e -
  • 47. Applications of X-ray Photoelectron Spectroscopy (XPS)
  • 48. XPS Analysis of Pigment from Mummy Artwork 150 145 140 135 130 Binding Energy (eV) PbO 2 Pb 3 O 4 500 400 300 200 100 0 Binding Energy (eV) O Pb Pb Pb N Ca C Na Cl XPS analysis showed that the pigment used on the mummy wrapping was Pb 3 O 4 rather than Fe 2 O 3 Egyptian Mummy 2nd Century AD World Heritage Museum University of Illinois
  • 49. Analysis of Carbon Fiber- Polymer Composite Material by XPS Woven carbon fiber composite XPS analysis identifies the functional groups present on composite surface. Chemical nature of fiber-polymer interface will influence its properties. -C-C- -C-O -C=O
  • 50. Analysis of Materials for Solar Energy Collection by XPS Depth Profiling- The amorphous-SiC/SnO 2 Interface The profile indicates a reduction of the SnO 2 occurred at the interface during deposition. Such a reduction would effect the collector’s efficiency. Photo-voltaic Collector Conductive Oxide- SnO 2 p-type a-SiC a-Si Solar Energy SnO 2 Sn Depth 500 496 492 488 484 480 Binding Energy, eV Data courtesy A. Nurrudin and J. Abelson, University of Illinois
  • 51. Angle-resolved XPS  =15°  = 90° More Surface Sensitive Less Surface Sensitive Information depth = dsin  d = Escape depth ~ 3   = Emission angle relative to surface  =  Inelastic Mean Free Path  
  • 52.