Difference between revisions of "Photoelectron Spectrometer XPS and UPS"
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What is the Problem? [[Image:Surface_electron_spectroscopies.jpg|thumb|right|400px |XPS uses high energy X-ray photons to excite “core” electrons in the near-surface region UPS uses lower energy photons in the deep UV region to excite valence electrons.]] | ===What is the Problem?=== [[Image:Surface_electron_spectroscopies.jpg|thumb|right|400px |XPS uses high energy X-ray photons to excite “core” electrons in the near-surface region UPS uses lower energy photons in the deep UV region to excite valence electrons.]] | ||
OLEDs and OPVs consist of thin films of organic materials, sandwiched between contacting electrodes. We need analytical tools which tell us: | OLEDs and OPVs consist of thin films of organic materials, sandwiched between contacting electrodes. We need analytical tools which tell us: | ||
*Elemental composition of metal, metal oxide and organic surfaces (top 1-10 nm) | *Elemental composition of metal, metal oxide and organic surfaces (top 1-10 nm) | ||
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*The frontier orbital energies which control rates of charge transfer, photopotentials, onset voltages, etc. | *The frontier orbital energies which control rates of charge transfer, photopotentials, onset voltages, etc. | ||
What is our approach? | ===What is our approach? Physics of XPS and UPS=== | ||
We use high-vacuum surface electron spectroscopies: X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy to provide the elemental, molecular and energetic information we require about these materials. | We use high-vacuum surface electron spectroscopies: X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy to provide the elemental, molecular and energetic information we require about these materials. | ||
[[Image:PS-surfaceanalysis.jpg|thumb|right|400px |The small sampling depth of XPS and UPS arises because most of the photoelectrons generated do NOT make it out of the solid – they are scattered below the surface and not detected. Only those within 1-10 nm of the surface get out and can be analyzed.]] | [[Image:PS-surfaceanalysis.jpg|thumb|right|400px |The small sampling depth of XPS and UPS arises because most of the photoelectrons generated do NOT make it out of the solid – they are scattered below the surface and not detected. Only those within 1-10 nm of the surface get out and can be analyzed.]] | ||
===Data interpretation=== | |||
Revision as of 08:18, 22 April 2009
===What is the Problem?===
OLEDs and OPVs consist of thin films of organic materials, sandwiched between contacting electrodes. We need analytical tools which tell us:
- Elemental composition of metal, metal oxide and organic surfaces (top 1-10 nm)
- The molecular state of those elements in that same region
- The frontier orbital energies which control rates of charge transfer, photopotentials, onset voltages, etc.
What is our approach? Physics of XPS and UPS
We use high-vacuum surface electron spectroscopies: X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy to provide the elemental, molecular and energetic information we require about these materials.
