Final State Effects

 

 

FINAL State Effects that can be Measured by XPS

  • Auto-ionization is a FINAL State Effect
  • Response of atom to photo-ionization
  • Configuration-Interaction effects
  • Final state Lifetime effect
  • Final state correlation effects
  • Final state vibration excitations
  • Photoelectron hole
  • Asymmetric line shape
  • Atom% composition
  • Empirical ratios (without hydrogen)
  • Core peak intensities
  • Valence peak intensities
  • ?? Core peak shifts
  • ?? Valence peak positions
  • Shake-up
  • Shake-off
  • Multiplet Splitting
  • Intrinsic peaks (satellites, losses) due to electron screening
  • Extrinsic peaks (satellites, losses) occur during electron transport to surface
  • Plasmon excitations – surface and bulk
  • Relaxation energies (~10-30 eV)
  • Final state charge distributions
  • Born-Haber cycle – Thermochemical energies
  • ?? Molecular Orbitals
  • ?? Chemisorption
  • ?? Film thickness
  • Photo-electron Diffraction
  • Atomic Geometries
  • Final state effects can involve multiple electrons

 

 

 

Initial State Effects that can be Measured by XPS

  • Spin-Orbit splitting is an Initial State Effect for Molecular Species
  • Chemical State Shift
  • Density of States (bandwidth)
  • Photon Absorption
  • Photo-ionization
  • Charge Distribution
  • Bond polarization
  • Ionicity or ionic character
  • Valence Orbital Energy Levels, Symmetries and Atomic orbital make-up
  • Electron configuration
  • Electron-electron interactions (J-J, JT, RS ??)
  • Surface Core Level Shifts (SCLS)
  • Auger Parameters
  • Auger Chemical Shifts
  • Peak FWHM
  • Hole Lifetime
  • Lifetime Broadening
  • Vibrational effects
  • Band-gap
  • Work Function
  • To evaluate Initial State Effects in solids it is also necessary to measure the work function of the sample.
    The latter complication is avoided when the solid is studied in the gas phase.
  • ?? Surface effects – dangling bonds, Tamm state, space image, space charge

 

 

Sequence of Actions Depiction – Starting from Initial State and Ending in Final State

 

 

  • Relaxation Effects
    • Atomic
      • Removal of an electron from an atomic orbital creates a positive hole toward which the passive electron orbitals relax to minimize the systems total energy. In this case, the electrons quantum numbers do not change.
    • Molecular
      • The relaxation energy accompanying photoemission from core levels in molecules is nearly always large than in atoms because additional electronic harge can flow toward the positive hole.  It is convenient, though arbitrary to consider the total relaxation energy to be the sum of the atomic plus “extra-atomic” contributions.
  • Multiplet Splitting Effects
    • S-level orbitals
    • P-level orbitals – Transition Metals
    • Rare earth
  • Multi-Electron Excitations
    • Shake-up
    • Shake-off
    • Multi-electron excitation in metals
    • Core-peak Satellites in Transition-metal and Rare-earth Compounds
    • Other effects
  • Vibrational Effects

 

 

EXAMPLES of Final State Effects