Biophy Research/Our techniques / XPS/ESCA
Our team of experts will accompany you throughout your XPS project, from the formulation of your problem to its resolution.

With state-of-the-art equipment and a range of modules including the argon cluster gun, we will provide you with comprehensive results and a detailed report that you can discuss with our engineers.


Not sure if the XPS is right for you? Do not hesitate to contact us so that together we can find the right technique for your needs.
 


XPS principle 


X-Ray Photoelectron Spectroscopy (XPS) or Electron Spectroscopy for Chemical Analysis (ESCA) allows to determine the elementary composition as well as the chemical signature on the extreme surface of a material (3-10 nm depth).
Depth profiling is also possible at greater depths depending on the sample nature, alternating etching/analysis cycles with monoatomic (for inorganic materials) or gas cluster ion source (for organic materials). This technique can detect all elements except hydrogen and helium.

XPS gives you access to the elemental composition and chemical signature (detection of all elements except H and He) of a surface over 3 to 10 nm.


In an XPS analysis the sample is irradiated with known wavelength X-Ray photons generated by a monochromatic aluminum source. When irradiation occurs, sample atoms on the extreme surface emit photoelectrons by « photoelectric effect ». These have specific binding energies depending on the element and its chemical environment.
This non-destructive analysis is performed in ultra-high vacuum (10-8 - 10-9 mbars) and provides the following information : elementary chemical composition (with an LOD of 0.3 atomic %) and chemical environment of the extreme surface atoms (3 – 10 nm). 

Three operating modes according to your needs.

SPECTROSCOPY MODE

Elemental and chemical analysis of the extreme surface
This mode is available in different configurations: point analysis (a few tens of µm2 to 300 x 700 µm2), linescan (a few mm per cm in x or y) and grid (for homogeneity studies on surfaces up to cm2). The depth of analysis varies between 3 and 10 nm (depending on the angle between the detector and the surface normal).
 

IMAGING MODE

Visualisation of the spatial elemental distribution on the surface of samples
Particularly suitable for heterogeneous samples (corrosion pits, contamination areas, lithography, etc.) with a lateral resolution of ~ 3 µm.
 

PROFILE MODE

Distribution of atomic concentrations in the depth of samples:
non-destructive method for the first 10 nm, most often used to detect surface segregation. By varying the detection angle, it is possible to establish concentration profiles according to the depth analysed.
concentration profiles for greater thicknesses (from 100 nm to µm), by alternating analysis and abrasion sequences.

XPS applications


XPS allows to study the elementary/chemical composition of the elements that are present on the extreme surface as well as the elements that are present into more internal material layers/interfaces. These materials can be from a wide array of industrial sectors: microelectronic, metallurgy (corrosion, oxidation), polymers (packaging, chemical functionalization), chemistry, pharma, cosmetic (hair, skin), aerospace/automotive (adhesion, painting, etching).
With extensive field applications, here are some examples for practical XPS analysis

 
Evaluation by XPS of the contribution of an atmospheric plasma treatment on the extreme surface chemistry of a PET Your thematics
Characterization of a polyethylene terephthalate by XPS Your thematics
XPS evaluation of oxidation degrees Your thematics
XPS measurement of the homogeneity of a PDMS plasma treatment on carbon fibers Your thematics
Measurement by XPS of the recovery rate of a cosmetic treatment on natural skin Your thematics
The argon cluster gun, an innovation for XPS profiles of coated glasses Your thematics

XPS technical specifications

  • Monochromatic AlKα source
  • Signal detected: photoelectrons
  • Elements detected: all except H and He
  • Quantitative & stoichiometric analysis with a LOD of the order of 0.3 atomic %
  • 27 x 27 µm2 spatial resolution in µ-analysis mode (conventional probe size: 300 x 700 µm2)
  • Spatial resolution of 3 µm in imaging mode
  • Energy resolution: 0.48 eV (FWHM) on Ag3d5/2 and 0.8 eV (FWHM) on O-C=O (PET)
  • Angular resolution of 1°
  • Charge neutralization for insulator analysis
  • Ar+ monoatomic gun and Arn+ clusters for stripping and depth distribution profile

XPS strengths

  • Analysis of many materials: organic, powders, biological samples, insulators (papers, plastics, polymer films, glasses, ceramics...), conductors (silicon, steel, metals, alloys...)
  • Very high sensitivity at the extreme surface (first nm)
  • Identification of the chemical state of surfaces for all elements except H and He
  • Quantitative method, also for chemical state differences (oxidation degrees...) 
  • Profiling of deeper layers with measurement of concentrations at matrix level
  • Estimation of thickness of oxide layers (if < 10 nm)
Do you have any questions? Do not hesitate to contact us!