Ion Scattering Spectroscopy (ISS)

Ion Scattering Spectroscopy Main Image
Overlay of 3 ISS survey scans taken on 3 different film species, showing peak separation for Copper (Cu), Silver (Ag), and Gold (Au)

Ion scattering spectroscopy (ISS) provides quantitative elemental composition information from the very outermost atomic layer of a surface.

Strengths

  • Maximally surface-selective: signal isolated from outermost atomic monolayer
  • Highly sensitive, quantitative elemental composition
  • No calibration standards required for quantification
  • Nondestructive analysis
  • Can measure buried interfaces via depth profiling

Limitations

  • Difficult to accurately measure light-element films over heavy-element substrates
  • Surfaces must be clean to get good results

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Sample Requirements

ISS Example Outputs

Overlay of 3 ISS survey scans taken on 3 different film species, showing peak separation for Copper (Cu), Silver (Ag), and Gold (Au)

Overlay of 3 ISS survey scans of a sputtered Platinum (Pt) film, captured after 3 sputtering segments: at 0 seconds (before sputtering), an oxide layer is present; after 60 seconds of sputtering, the O peak is nearly extinguished, and the Pt signal is very strong; after 90 seconds of sputtering, the O peak is fully eliminated

ISS Instruments Used

ThermoFisher Scientific Nexsa

ThermoFisher Scientific Nexsa

  • Spot Size: 1 mm
  • Sensitivity: depends on the noble gas species used for the ion beam
  • X-ray Source: monochromated, micro-focused, high-efficiency Al Kα X-ray Anode
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In ISS measurements, a low-energy probe beam of noble gas ions is applied to the sample surface. These ions undergo elastic back-scattering interactions with the outermost surface atoms, during which energy – in the form of momentum – is transferred. The magnitude of momentum transfer is dependent on the elemental species of the sample atom: lighter elements (with closer relative mass to the probe ions) will cause greater reduction in the noble ion’s kinetic energy.

The ISS detector measures the amount of back-scattered noble ions with particular kinetic energies, and scans over a range of energy values up to the incident beam energy.

By taking the difference between the original and final kinetic energies of the back-scattered ions, the system produces a spectrum of peaks with energy indicative of elemental species, and intensity indicative of quantitative concentration.

Learn more about using Ion Scattering Spectroscopy services today!