Facilities in the MARPOS Laboratory

The MARPOS Laboratory is equipped with advanced positron-based spectroscopy systems that enable comprehensive investigation of defects, free volume, and electronic environments in a wide range of materials. Our facility currently includes two main instrument groups: bulk measurement systems and a variable-energy positron beam system (VEPOS) for depth-resolved studies.

Bulk Measurement Systems

We operate two complementary positron annihilation techniques:

Positron Annihilation Lifetime Spectroscopy (PALS)
A fast–fast coincidence setup is used to measure the lifetime of positrons and ortho-positronium (o-Ps). Lifetime components provide precise information about free-volume hole sizes, vacancy-type defects, and microstructural changes in materials.

Doppler Broadening Spectroscopy (DBS)
DBS is a high-resolution system that analyzes the energy broadening of the 511 keV annihilation photons. DBS reveals chemical surroundings and distinguishes between vacancy concentrations and impurity-related defects through S–W parameter analysis.

Together, these systems allow quantitative defect characterization from the atomic to the nanometer scale.

---

Variable Energy Positron Beam System (VEPOS)

Our VEPOS system enables depth-profiling of surfaces, thin films, and interfaces by tuning the incident positron energy up to 30 keV. By controlling the implantation depth, we can map vacancy-type and chemical defects as a function of depth with nanometer precision.

The beamline supports:

Doppler Broadening Spectroscopy (DBS) — fully operational for depth-resolved S–W analysis.

Positron Annihilation Lifetime Spectroscopy (PALS) — currently under development and being integrated into the beam system.

This combination allows the MARPOS Laboratory to investigate both bulk and near-surface defect structures with high sensitivity.