Angle-resolved X-ray Photoelectron Spectroscopy

The effective sampling depth in XPS can be varied (for flat samples) by changing the angle of the sample with respect to the detector. The actual depth sampled, d, is given by the equation:
d = 3λ sin θ,
where λ is the inelastic mean free path of the photoelectron and
θ is the angle between the sample surface and the analyzer acceptance plane.
arxps
  • Thus at   θ = 90o the sample surface is perpendicular to the line of acceptance of the analyzer, and d is the maximum sampling depth of 3λ. As θ is reduced then the sampling depth decreases.
http://www.uccs.edu/~tchriste/courses/PHYS549/549lectures/element.html

By comparing the relative intensities of peaks at the same kinetic energy over a number of different takeoff angles it is possible to calculate layer thickness. Alternately, comparing relative intensities at low and high take off angles indicates whether a species is enriched or depleted in the surface region. This is useful for the analysis of thin films on surfaces where it is possible to determine the molecular orientation to the surface.

References:

•                      P.J. Cumpson, in D. Briggs and J.T. Grant (Eds.), Surface Analysis by Auger and X-ray Photoelectron Spectroscopy, IM publications and SurfaceSpectra Limited: Chichester: Manchester, 2003, Chapter Angle-Resolved X-Ray Photoelectron Spectroscopy.

•                      Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) by Royston Paynter



For more details, please contact us (kartyush@unm.edu).

Material Synthesis:
Aerosol Synthesis Lab
Sol-Gel Synthesis Lab
Catalysis Lab


facilities