DOCSLIB.ORG

And Auger Electron Spectroscopy (AES)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
And Auger Electron Spectroscopy (AES) 6/9/2008 Advanced Materials Characterization Workshop X‐ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) Rick Haasch, Ph.D. Supported by the U.S. Department of Energy under grants DEFG02-07-ER46453 and DEFG02-07-ER46471 © 2008 University of Illinois Board of Trustees. All rights reserved. What is Surface Analysis? >1000 nm 100 nm <10 nm Bulk Analysis Thin- Thin-filmfilm Analysis Surface Analysis The Study of the Outer-Most Layers of Materials (~10 nm). 2 © 2008 University of Illinois Board of Trustees. All rights reserved. 1 6/9/2008 Particle Surface Interactions Primary beam Secondary beam (source) (spectrometers, detectors) Ions Ions Elec trons Elec trons Photons Photons Vacuum 3 © 2008 University of Illinois Board of Trustees. All rights reserved. Spatial resolution versus Detection Limit 4 © 2008 University of Illinois Board of Trustees. All rights reserved. 2 6/9/2008 Particle Surface Interactions Photoelectron Spectroscopy Ions Ions Electrons Electrons Photons Photons Joe E. Greene2) Vacuum 5 © 2008 University of Illinois Board of Trustees. All rights reserved. X-ray Photoelectron Spectroscopy (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. X-ray1 Photoelectron spectroscopy, based on the photoelectric effect,2,3 was developed in the mid-1960’s as a practical technique by Kai Siegbahn and his research group at the University of Uppsala, Sweden.4 Wilhelm Conrad Röntgen Heinrich Rudolf Hertz Albert Einstein Kai M. Siegbahn 1. W. Röntgen, 1901 Nobel Prize in Physics “in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him.” 2. H. Hertz, Ann. Physik 31,983 (1887). 3. A. Einstein, Ann. Physik 17,132 (1905). 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.” 4. 4. K. Siegbahn, Et. Al.,Nova Acta Regiae Soc.Sci., Ser. IV, Vol. 20 (1967). 1981 Nobel Prize in Physics “for his contribution to the development of high resolution electron spectroscopy.” 6 © 2008 University of Illinois Board of Trustees. All rights reserved. 3 6/9/2008 X-ray Photoelectron Spectroscopy Small Area Detection Electrons are extracted only from a narrow solid angle. X-ray Beam X-ray penetration depth ~1μm. Electrons can be excited in this 10 nm entire volume. 10 μm- 1 mm dia. X-ray excitation area ~1 mm-1 cm diameter. Electrons are emitted from this entire area 7 © 2008 University of Illinois Board of Trustees. All rights reserved. Photoelectron and Auger Electron Emission KE (measured) = hν (known) - BE - Φspec (calibrated) Emitted Auger Electron Eincident X-ray = hν Free Electron Level Φ Conduction Band Conduction Band Fermi Level Valence Band Valence Band BE 2p L2,L3 2s L1 1s K Calculate: BE = hν - KE - Φspec BE – binding energy depends on Z, i.e. characteristic for the element 8 © 2008 University of Illinois Board of Trustees. All rights reserved. 4 6/9/2008 Photoelectron and Auger Electron Emission KE (measured) = hν (known) - BE - Φspec (calibrated) Emited X-ray Photon Eincident X-ray = hν Free Electron Level Φ Conduction Band Conduction Band Fermi Level Valence Band Valence Band BE 2p L2,L3 2s L1 1s K Calculate: BE = hν - KE - Φspec BE – binding energy depends on Z, i.e. characteristic for the element 9 © 2008 University of Illinois Board of Trustees. All rights reserved. Photoelectron and Auger Electron Emission 10 © 2008 University of Illinois Board of Trustees. All rights reserved. 5 6/9/2008 Photoelectron and Auger Electron Emission 11 © 2008 University of Illinois Board of Trustees. All rights reserved. Photoelectron and Auger Electron Emission Energy Scales Conduction Band 0 Fermi Level Valence Band Binding Energy Kinetic Energy Photoelectron Lines Auger Electron Lines 12 © 2008 University of Illinois Board of Trustees. All rights reserved. 6 6/9/2008 Photoelectron and Auger Electron Emission X-ray Photoelectron Spectroscopy Conduction Band Fermi Level Valence Band Al Kα = 1486.6 eV MKMg Kα = 1253. 6 e V XPS can probe all of the orbitals in only the light elements. e.g. BE C 1s = 285 eV, Mg 1s =1304 eV, Au 1s ≈ 81000 eV Predominantly, soft X-rays are used. 13 © 2008 University of Illinois Board of Trustees. All rights reserved. Photoelectron and Auger Electron Emission Ultraviolet Photoelectron Spectroscopy Conduction Band Fermi Level Valence Band He II = 40.8 eV He I = 22.4 eV 14 © 2008 University of Illinois Board of Trustees. All rights reserved. 7 6/9/2008 Surface Sensitivity: Electron Spectroscopy Inelastic Mean-Free Path: The mean distance an electron can travel between inelastic scattering events. Inelastic mean-free paths (calculated) based on TPP-2* 5 4.5 m) 4 XPS 3.5 Carbon 3 Aluminum 2.5 Copper Silver 2 Gold 1.5 elastic Mean-Free Path(n Mean-Free elastic 1 n I 0.5 0 0 500 1000 1500 2000 2500 3000 Kinetic Energy (eV) Electrons travel only a few nanometers through solids. *S. Tanuma, C. J. Powell, D. R. Penn, Surface and Interface Analysis, 17, 911-926 (1991). 15 © 2008 University of Illinois Board of Trustees. All rights reserved. Surface Sensitivity: Electron Spectroscopy Inelastic Mean-Free Path: The mean distance an electron can travel between inelastic scattering events. Inelastic mean-free paths (calculated) based on TPP-2* 5 4.5 m) 4 Auger 3.5 Carbon 3 Aluminum 2.5 Copper Silver 2 Gold 1.5 elastic Mean-Free Path(n Mean-Free elastic 1 n I 0.5 0 0 500 1000 1500 2000 2500 3000 Kinetic Energy (eV) Electrons travel only a few nanometers through solids. *S. Tanuma, C. J. Powell, D. R. Penn, Surface and Interface Analysis, 17, 911-926 (1991). 16 © 2008 University of Illinois Board of Trustees. All rights reserved. 8 6/9/2008 Surface Sensitivity: Electron Spectroscopy Assuming Inelastic Scattering Only 1 Beer-Lambert relationship: 0.8 I = I0exp(-d/λcosθ) where d = depth 0.6 λ = Inelastic mean free path I/I0 0.4 at 3λ, I/I0 = 0.05 0.2 at 1000 eV, λ≈1.6 nm 0 01234 d/λ 95% of the signal comes from within 5 nm of the surface or less! 17 © 2008 University of Illinois Board of Trustees. All rights reserved. Surface Sensitivity: Electron Spectroscopy Surface Analysis Advantage Disadvantage Extremely surface sensitive! Extremely surface sensitive! 18 © 2008 University of Illinois Board of Trustees. All rights reserved. 9 6/9/2008 Ion Sputtering 0.5 – 5 keV Ar+ •Ions striking a surface interact with a number of atoms in a series collisions. • recoiled target atoms in turn collide with atom at rest generating a collision cascade. • The initial ion energy and momentum are distributed to among the target recoil atoms. • When Ei > 1 keV, the cascade is “linear”, i.e. approximated by a series of binary collisions in a stationary matrix. Causes physical and chemical damage P. Sigmund, “Sputtering by ion bombardment: theoretical concepts,” in Sputtering by particle bombardment I, edited by R. Behrish, Springer-Verlag, 1981 19 © 2008 University of Illinois Board of Trustees. All rights reserved. X-ray Photoelectron Spectrometer Hemispherical Energy Analyzer X-ray Monochromator Extraction Detector Lenses Sample 54.7 X-ray Source 20 © 2008 University of Illinois Board of Trustees. All rights reserved. 10 6/9/2008 X-ray Photoelectron Spectrometer Physical Electronics PHI 5400 21 © 2008 University of Illinois Board of Trustees. All rights reserved. Elemental Shifts Pure Element Fermi Level ElectronElectron--electronelectron Binding repulsion Energy Look for changes Electron here by observing electron binding ElectronElectron--nucleusnucleus energies attraction Electron- Nucleus Separation Nucleus 22 © 2008 University of Illinois Board of Trustees. All rights reserved. 11 6/9/2008 Elemental Shifts 23 © 2008 University of Illinois Board of Trustees. All rights reserved. Elemental Shifts Core Level Binding Energies 1400 1s 2s 2p 1200 1000 3s 800 3p 600 3d Binding Energy (eV) Binding Energy 400 200 4s 4p 0 0 5 10 15 20 25 30 35 40 45 50 Atomic Number 24 © 2008 University of Illinois Board of Trustees. All rights reserved. 12 6/9/2008 Elemental Shifts First-Row Transition Metals Binding Energy (eV) Element 2p3/2 3p Δ Sc 399 29 370 Ti 454 33 421 V 512 37 475 Cr 574 43 531 Mn 639 48 591 Fe 707 53 654 Co 778 60 718 Ni 853 67 786 Cu 933 75 858 Zn 1022 89 933 25 © 2008 University of Illinois Board of Trustees. All rights reserved. Elemental Shifts: An Example First-Row Transition Metal Nitr ides: ScN, TiN, VN, and CrN Sc2p Metal and N Auger Lines Sc2s N1s Sc3p ScN Sc3s Ti2p Ti2s N1s Ti3p TiN Ti3s V2p V2s N1s V3p VN V3s ounts (arb. units) Cr2p C Cr2s N1s Cr3p CrN Cr3s 1200 1000 800 600 400 200 0 Binding energy (eV) Surface Science Spectra, 7, 167-280, 2000. 26 © 2008 University of Illinois Board of Trustees. All rights reserved. 13 6/9/2008 Chemical Shifts Electronegativity Effects Carbon-Oxygen Bond Oxygen Atom Electron-oxygen atom attraction Valence Level (Oxygen Electro- C 1s C 2p negativity) Binding Core Level Energy Shift to higher C 1s binding energy Electron-nucleus attraction (Loss of Electronic Screening) Carbon Nucleus 27 © 2008 University of Illinois Board of Trustees. All rights reserved. Chemical Shifts Functional C 1s Binding Group Energy (eV) hydrocarbon C-H, C-C 285.0 amine C-N 286.0 alcohol, ether C-O-H, C-O-C 286.5 Cl bound to C C-Cl 286.5 F bound to C C-F 287.8 carbonyl C=O 288.0 28 © 2008 University of Illinois Board of Trustees.
Load more

Recommended publications
  • X-Ray Photoelectron Spectroscopy (XPS)
    XX--RayRay PhotoelectronPhotoelectron SpectroscopySpectroscopy (XPS)(XPS) Louis Scudiero http://www.wsu.edu/~scudiero; 5-2669 Electron Spectroscopy for Chemical Analysis (ESCA) • The basic principle of the photoelectric effect was enunciated by Einstein [1] in 1905 E = hν There is a threshold in frequency below which light, regardless of intensity, fails to eject electrons from a metallic surface. hνc > eΦm where h is the Planck constant ( 6.62 x 10-34 J s ) and ν– the frequency of the radiation • In photoelectron spectroscopy such XPS, Auger and UPS, the photon energies range from 20 -1500 eV (even higher in the case of Auger, up to 10,000eV) much greater than any typical work function values (2-5 eV). • In these techniques, the kinetic energy distribution of the emitted photoelectrons (i.e. the number of emitted electrons as a function of their kinetic energy) can be measured using any appropriate electron energy analyzer and a photoelectron spectrum can thus be recorded. [1] Eintein A. Ann. Physik 1905, 17, 132. • By using photo-ionization and energy-dispersive analysis of the emitted photoelectrons the composition and electronic state of the surface region of a sample can be studied. • Traditionally, these techniques have been subdivided according to the source of exciting radiation into : • X-ray Photoelectron Spectroscopy (XPS or ESCA) - using soft x-ray (200 - 1500 eV) radiation to examine core-levels. • Ultraviolet Photoelectron Spectroscopy (UPS) - using vacuum UV (10 - 45 eV) radiation to examine valence levels. • Auger Electron Spectroscopy (AES or SAM) – using energetic electron (1000 – 10,000 eV) to examine core-levels. • Synchrotron radiation sources have enabled high resolution studies to be carried out with radiation spanning a much wider and more complete energy range ( 5 - 5000+ eV ) but such work will remain, a very small minority of all photoelectron studies due to the expense, complexity and limited availability of such sources.
    [Show full text]
  • Roadmap for Photoelectron Spectroscopy
    Roadmap for Photoelectron Spectroscopy Prepared on behalf of EPSRC by David Payne, Imperial College London Preface This roadmap has been prepared in consultation with the community over the last few years, during which time there have been a number of significant developments that have either directly or indirectly affected the PES community. These include the recently announced EPSRC Mid-Range Facility for XPS at the Research Complex at Harwell (HarwellXPS), as well new equipment being acquired as part of the Sir Henry Royce Institute. Whilst the conclusions from this exercise, and the recommendations remain unchanged, an exercise is now underway to capture some of the impacts of these changes. It is planned for an updated roadmap to become available in the next 6 months. 2 Contents page 1. Executive Summary...............................................................................................................................................................................................................................................................3 2. Key Findings and Recommendations...................................................................................................................................................................................................4 3. Introduction........................................................................................................................................................................................................................................................................................6
    [Show full text]
  • Photoelectron Spectroscopy on Atoms, Molecules and Clusters
    Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 375 Photoelectron Spectroscopy on Atoms, Molecules and Clusters The Geometric and Electronic Structure Studied by Synchrotron Radiation and Lasers TORBJÖRN RANDER ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 UPPSALA ISBN 978-91-554-7047-0 2007 urn:nbn:se:uu:diva-8343 ! " #! !$ %! & ' "!$ ( %$ $ #! ) * + ,$ %! - ' ) ) ) ! ( .$ * $ $ / $ $ 0)12 /334343$ * " 5 $ %! " ! " ! ! 5 " ! 6$ 0 ! ! 7 8 ,91 *:8 *:; *:<= 2= 2 < > ! " " ! ! & "!$ ! 3 ! 7;#)> ! $ ! ! 7 #)> *" 7(*)> 3 " 3 72';*?)> ! $ , " ! ! 7?%> +@3# ! 7+#> & $ %! " & " 7+> ! $ ( ! ! ,9 1 8 $ %! ! 2 ! !A ! " !2 ! ! $ %! " ! ,9 1 ! ! ,9 1 ! ! ! 5 $ %! ! 8 < ; " * " ! " $ %! !53 & ! 2 <$ . 2 ! ! & " " $ %! !53 & & !A ! " ! ! " 3 <$ ? ' . *5 ' - ;3 ! 7;#)> ( *" 7(*)> 23!! 3 72';*?)> ! 7 #)> " 3 7 ?> ) # 8" 1 ! *" ; < + " , ! , ! " #" $ % &'(" " )*+&,-, " B % 6C ( 0))2 D3D4 0)12 /334343 3/4 7! :: $5$: E F 3/4> “Och kallas därför höga bergen hos oss fjäll, av orsak att där oppå inga trän eller örter växa, utan de är glatta och bara såsom fjäll uppå en fisk” – Olof Rudbäck d. ä.
    [Show full text]
  • Unit 3 :Electronic Spectroscopy Contents
    UNIT 3 :ELECTRONIC SPECTROSCOPY CONTENTS • PHOTOELECTRON SPECTROSCOPY-INTRODUCTION • PRINCIPLE • INSTRUMENTATION INTRODUCTION • Photoelectron spectroscopy (PES) is the energy measurements of photoelectrons emitted from solids, gases, or liquids by the photoelectric effect. • Depending on the source of ionization energy, PES can be divided accordingly into Ultraviolet Photoelectron Spectroscopy (UPS) and X- ray Photoelectron Spectroscopy The photoelectric effect is a phenomenon in which electrons are ejected from the surface of a metal when light is incident on it. These ejected electrons are called photoelectrons. It is important to note that the emission of photoelectrons and the kinetic energy of the ejected photoelectrons is dependent on the frequency of the light that is incident on the metal’s surface. The process through which photoelectrons are ejected from the surface of the metal due to the action of light is commonly referred to as photoemission. Explaining the Photoelectric Effect: The Concept of Photons The photoelectric effect cannot be explained by considering light as a wave. However, this phenomenon can be explained by the particle nature of light, in which light can be visualized as a stream of particles of electromagnetic energy. These ‘particles’ of light are called photons. The energy held by a photon is related to the frequency of the light via Planck’s equation: E = h휈 = hc/λ Where, •E denotes the energy of the photon •h is Planck’s constant •휈 denotes the frequency of the light •c is the speed of light (in a vacuum) •λ is the wavelength of the light Threshold Energy for the Photoelectric Effect For the photoelectric effect to occur, the photons that are incident on the surface of the metal must carry sufficient energy to overcome the attractive forces that bind the electrons to the nuclei of the metals.
    [Show full text]
  • Introduction to X-Ray Photoelectron Spectroscopy
    Introduction to x-ray photoelectron spectroscopy Cite as: J. Vac. Sci. Technol. A 38, 063204 (2020); https://doi.org/10.1116/6.0000412 Submitted: 22 June 2020 . Accepted: 31 August 2020 . Published Online: 24 September 2020 Fred A. Stevie, and Carrie L. Donley COLLECTIONS Paper published as part of the special topic on Special Topic Collection: Reproducibility Challenges and Solutions ARTICLES YOU MAY BE INTERESTED IN Assessment of the frequency and nature of erroneous x-ray photoelectron spectroscopy analyses in the scientific literature Journal of Vacuum Science & Technology A 38, 061204 (2020); https:// doi.org/10.1116/6.0000685 XPS guide: Charge neutralization and binding energy referencing for insulating samples Journal of Vacuum Science & Technology A 38, 031204 (2020); https:// doi.org/10.1116/6.0000057 Procedure which allows the performance and calibration of an XPS instrument to be checked rapidly and frequently Journal of Vacuum Science & Technology A 38, 043206 (2020); https:// doi.org/10.1116/6.0000224 J. Vac. Sci. Technol. A 38, 063204 (2020); https://doi.org/10.1116/6.0000412 38, 063204 © 2020 Author(s). ARTICLE avs.scitation.org/journal/jva Introduction to x-ray photoelectron spectroscopy Cite as: J. Vac. Sci. Technol. A 38, 063204 (2020); doi: 10.1116/6.0000412 Submitted: 22 June 2020 · Accepted: 31 August 2020 · View Online Export Citation CrossMark Published Online: 24 September 2020 Fred A. Stevie1,a) and Carrie L. Donley2,b) AFFILIATIONS 1Analytical Instrumentation Facility, North Carolina State University, Raleigh, North Carolina 27695 2Chapel Hill Analytical and Nanofabrication Laboratory, University of North Carolina, Chapel Hill, North Carolina 27599 Note: This paper is part of the Special Topic Collection on Reproducibility Challenges and Solutions.
    [Show full text]
  • Electron Spectroscopy of Rutile-Type Metal Oxides Sigrun Eriksen B.Sc
    1 Electron Spectroscopy of Rutile-type Metal Oxides r Sigrun Eriksen B.Sc. A.R.C.S. A thesis submitted for the degree of Doctor of Philosophy of the University of London and for the Diploma of Membership of Imperial College. Department of Chemistry Imperial College London SW7 2AZ August 1987 2 Abstract This thesis presents a study of defective and defect-free rutile TiO (110) surfaces, using ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HREELS). The use of argon ion and electron bombardment for creation of surface defects is investigated. An oxygen -20 -2 desorption cross section of 1.5 x 10 cm is found for electron irradiation, and a desorption mechanism suggested. An electronic excitation due to the oxygen vacancies is identified; this modifies the effective surface dielectric constant. The oscillator strength for this excitation is found to be 0.1, indicating an allowed transition. The adsorption of water on the TiO2(110) surface is also studied. From HREELS and He(II) UPS, it is found that water will not adsorb on a defect-free TiO^MIO) surface at 300K, but will adsorb on a surface in which oxygen vacancy defects have been created. It is shown that this adsorption involves dissociation of the water molecule, leaving 0-H species bonded to the surface. Finally, the effects of oxygen vacancies on the rutile SnO^MIO) surface are investigated. It is confirmed that argon ion bombardment gives rise to selective oxygen loss, and the Sn species on the 2 + 4 + resulting defective surface are Sn and Sn ; total oxygen loss is never greater than 502.
    [Show full text]
  • X-Ray Photoelectron Spectroscopy
    XX--rayray PhotoelectronPhotoelectron SpectroscopySpectroscopy RogerRoger Smart,Smart, StewartStewart McIntyre,McIntyre, MikeMike Bancroft,Bancroft, IgorIgor BelloBello && FriendsFriends DepartmentDepartment ofof PhysicsPhysics andand MaterialsMaterials ScienceScience CityCity UniversityUniversity ofof HongHong KongKong SurfaceSurface ScienceScience Western,Western, UWOUWO Introduction Photoelectric effect Photoelectric effect Einstein, Nobel Prize 1921 Photoemission as an analytical tool Kai Siegbahn, Nobel Prize 1981 XPS, also known as ESCA, is the most widely used surface analysis technique because of its relative simplicity in use and data interpretation. XPS X-ray Photoelectron Spectroscopy ESCA Electron Spectroscopy for Chemical Analysis UPS Ultraviolet Photoelectron Spectroscopy PES Photoemission Spectroscopy AnalyticalAnalytical MethodsMethods --- X-ray Photoelectron Spectroscopy (XPS) Photon ν ϕ hν KE = h - (EB+ ) Kinetic Photoelectron Energy E 0 v XPS spectrum: φ Intensities of photoelectrons 0 Ef versus EB or KE VB Binding — Elemental identification and Energy 3s chemical state of element 2p 2s — Relative composition of the constituents in the surface region 1s — Valence band structure Binding Energy Reference K.E. = hνφ -B.E..F - sample - (φφ- ) K.E. = hνφ -B.E. - spec sample .F sample- = hνφ -B.E. - e .F spec Vacuum level Vacuum level φspec φsample Fermi level Fermi level B.E.F core level B.E..F = hνφ - K.E. - spec Instrumentation • Electron energy analyzer • X-ray source • Ar ion gun • Neutralizer • Vacuum system • Electronic controls • Computer system Ultrahigh vacuum system < 10-9 Torr (< 10-7 Pa) • Detection of electrons • Avoid surface reactions/ contaminations Background: Photoelectrons with energy loss Peak: Photoelectrons without energy loss Relative binding energies and ionization cross-section for U For p, d and f peaks, two peaks are observed.
    [Show full text]
  • X-Ray Photoelectron Spectroscopy (XPS)
    XX--RayRay PhotoelectronPhotoelectron SpectroscopySpectroscopy (XPS)(XPS) Louis Scudiero http://www.wsu.edu/~scudiero; 5-2669 Electron Spectroscopy for Chemical Analysis (ESCA) • The basic principle of the photoelectric effect was enunciated by Einstein [1] in 1905 E = hν There is a threshold in frequency below which light, regardless of intensity, fails to eject electrons from a metallic surface. hνc > eFm Where h - Planck constant ( 6.62 x 10-34 J s ), ν– frequency (Hz) of the radiation • In photoelectron spectroscopy such XPS, Auger and UPS, the photon energies range from 20 -1500 eV (even higher in the case of Auger, up to 10,000eV) much greater than any typical work function values (2-5 eV). • In these techniques, the kinetic energy distribution of the emitted photoelectrons (i.e. the number of emitted electrons as a function of their kinetic energy) can be measured using any appropriate electron energy analyzer and a photoelectron spectrum can thus be recorded. [1] Eintein A. Ann. Physik 1905, 17, 132. • By using photo-ionization and energy-dispersive analysis of the emitted photoelectrons the composition and electronic state of the surface region of a sample can be studied. • Traditionally, these techniques have been subdivided according to the source of exciting radiation into : • X-ray Photoelectron Spectroscopy (XPS or ESCA) - using soft x-ray (200 - 1500 eV) radiation to examine core-levels. • Ultraviolet Photoelectron Spectroscopy (UPS) - using vacuum UV (10 - 45 eV) radiation to examine valence levels. • Auger Electron Spectroscopy (AES or SAM) – using energetic electron (1000 – 10,000 eV) to examine core-levels. • Synchrotron radiation sources have enabled high resolution studies to be carried out with radiation spanning a much wider and more complete energy range ( 5 - 5000+ eV ) but such work will remain, a very small minority of all photoelectron studies due to the expense, complexity and limited availability of such sources.
    [Show full text]