Instrument: Thermo Fisher ESCALAB 250 Xi XPS


Surface and Thin Film Analysis


311 Chevron Science Center



The ESCALAB 250Xi is a fully digital state-of-the-art X-ray photoelectron spectrometer (XPS) capable of performing a large suite of surface analysis experiments. The instrument is used routinely for elemental analysis (Li-U) and for chemical state analysis, differentiating between the different functional groups that a given element is bonding to (for instance, C-C verses C=C verses C=O). 

The instrument is capable of conducting a wide range of surface analysis experiments. Some of these include:

  • XPS, X-ray photoelectron spectroscopy
    • Control of X-ray spot size from 900 to 200 um with monochromatic Al Ka X-rays and 0.5 m Rowland circle monochromator
    • In lens and external electron flood guns for analysis of insulators and non-conducting samples
    • Ultimate energy resolution <0.45 eV
  • UPS, ultraviolet photoelectron spectroscopy
    • measurement of valence band structure (similar to the density of states, DOS) and the Fermi edge
    • HeI and HeII (21.22 eV and 40.81 eV) excitation source
    • 100 meV energy resolution
  • ISS, low energy ion scattering spectroscopy
    • measurement of chemical composition of the upper atomic monolayer of the sample
    • 1 keV He+ ion source 
    • Energy resolution 12 eV FWHM at approximately 30,000 cps/nA ion current
  • REELS, reflected electron energy loss spectroscopy
    • measurement of geometry, electronic and optical properties via the dielectric function, and structure of absorbed species on the sample surface
  • TPD/TPRS, temperature programmed desorption/temperature programmed reaction spectroscopy
    • Allows analysis of gas-solid interactions by monitoring desorption of gas molecules as sample is heated
    • Gas dosing system for carrying out in situ reactions in both the analysis and load lock chamber
    • ​Single quadrupole mass analyzer for collection of mass spectra at pressure below 10-7 mbar
    • Temperature control of samples from 77 to 1000 K in both the analysis and load lock chamber
    • Reactions may be carried out from ultra-high vacuum conditions to atmospheric pressure
  • Small spot XPS
    • Use of magnetic immersion lens allows for selective analysis of areas smaller than the X-ray beam, down to 30 um or better
    • Allows for mapping of surface features on heterogeneous samples
  • XPS imaging
    • 128 element multichannel plate (MCP) detector for collection of images
    • full hyperspectral data collection for each image pixel
    • Spatial resolution better than 3 um
  • Angle resolved XPS (ARXPS)
    • for the depth profiling of thin films (< 10 nm)
    • full 5-axis motion control including 160o stage tilt
  • Depth profiling by Ar+ sputtering for thicker layered samples