Particle – matter interactions for ion microscopy

Optimization of sensitivity and quantification in SIMS

Secondary Ion Mass Spectrometry (SIMS) is a well-established and extremely powerful technique for the chemical analysis of surfaces and thin films. Its main advantages are:

• its excellent sensitivity
• its high dynamic range
• its good mass resolution
• its ability to distinguish between isotopes.

The use of cesium can dramatically increase the sensitivity of the analysis. We have therefore developed an add-on Cs deposition system allowing the sample surface to be coated with Cs prior to or during SIMS analysis for the purpose of optimizing analytical performances. This system presents several advantages, including:

• increased sensitivities in the negative secondary ion mode (ionization probabilities of 100% for elements with high electron affinities)
• minimization or elimination of the matrix effect in the negative secondary ion mode
• optimization of the sensitivities in the MCsx+ mode for efficient elimination of the matrix effect.

Contact: Patrick PHILIPP

Investigation of particle – matter interactions

For ion-beam-based microscopy, the development of new instruments, methods and applications requires the control of processes and mechanisms like particle sputtering and ionization. We are therefore investigating particle – surface interactions by:

• experimental studies
• numerical simulations:
  • Monte Carlo based on binary collision approximation
  • Molecular Dynamics (MD) simulations
  • Density Functional Theory (DFT) calculations.

The different aspects that are explored include:

• damage formation
• sputtering
• properties of ejected matter (e.g. energy and angular distributions)
• atomic mixing
• ionization of sputtered matter
• influence of surface contaminations
• etc.

Contact: Patrick PHILIPP