Spectroscopy

X-ray Photoelectron Spectroscopy (XPS)

X-ray Photoelectron Spectroscopy (XPS) is a quantitative spectroscopic technique that measures the elemental composition of the elements that exist within a material.

It is a surface chemical analysis technique that can be used to analyze the surface chemistry of a material in its "as received" state within approximately 6 nanometers or less of the surface. XPS is also known as ESCA, an abbreviation for Electron Spectroscopy for Chemical Analysis. Detection limits for most of the elements are in the parts per thousand range.

Small Spot X-ray Photoelectron Spectroscopy (XPS) using the Phi Quantera Scanning X-ray microprobe. The Quantera delivers the ability to perform XPS analysis on spots as small as 20 microns and do XPS imaging with ~ 10 micron lateral resolution.

Applications:

Unknown contamination identification on small features

Chemical bonding information (both surface and in-depth)

Chemical composition information

Metal surfaces

Treated surfaces

Chemically modified surfaces

Polymeric samples

Silicone contamination

Inorganic surfaces

Adhesion problems

Failure analysis

Competitive product analysis

Deformulation

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Work We've Done

Metallized Coating Analysis

A client wanted to know the composition of a metallized film deposited on a polymeric substrate. If the film thickness is too thin, techniques like Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) may sample too deep (nominally 1µm) and the elements on the surface of interest will be swamped by the signal from the elements underneath the layer of interest.

XPS has a much shallower sampling depth (nominally 6 nm). In this case, XPS (or ESCA) was used to conduct a survey scan to determine what elements were present in the metallized film. By conducting an XPS multiplex scan the binding energies were analyzed to determine the oxidation state and what element it was most likely bonded to in its chemical composition. This technique is also useful in detecting silicone contamination where adhesion may be an issue, especially in film packaging.

When there are more than one layer of a metallized film Auger Electron Spectroscopy (AES) may be used in conjunction with XPS or independently. For another client XPS was used in conjunction with AES to determine the number of layers and the chemical composition of each layer. AES allows for depth profiling while monitoring elemental composition. AES has been used for detecting metallized coatings up to 50 layers thick, as well as the elemental composition of each layer.

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