Course Objectives
• Learn about X-ray absorption fine structure (XAFS) and Photoelectron Diffraction (PED) techniques
• Learn about the modellisation of the XAFS and PED experimental data
• Understand local structures problems can be solved
• Be introduced to the developments of the instrumentation

Course Description

Overview of the Photoemission and X-ray absorption spectroscopies are applied to local structure determination both of ordered and not-ordered condensed matter systems. The modellisation of the experimental data of photoemission and optical absorption involving core levels gives access to the local structure around the atomic site of the material. Lessons are finalised to present the procedures connecting the experimental data to local structure.

The outline of the course is:
• Absorption and photoemission processes in solid state materials;

• Phenomenology: energy (absorption edge near and extended fine structure) and angular distribution. Effects of light polarisation. De-excitation processes (fluorescence decay and Auger recombination).

• Modellisation:
absorption and photoemission lineshape and intensity through the scattering of the excited electron around the absorption site (single and multiple scattering processes). Role of the nature (molecular orbital, extended states) of electronic states

• Instrumentation and experimental methods:
- Laboratory and synchrotron light sources;
- Electron (electron energy analysers) and photon (diodes, semiconductors, Si-Li, Ge-Li) detectors; Absorption measurements (drain current, - partial and total electron yield, fluorescence);
- Surface and volume sensitivity (free collision path, fluorescence versus electron yield);

• Case studies, experiment planning and data analysis;
• Strength and weakness of Photoelectron Diffraction and X-ray absorption Fine Structure techniques;
• Outline of available codes;

Who should attend?

Scientists and engineers in industry, government labs, or academia who wish to learn or review the fundamentals of x-ray absorption spectroscopy and Photoelectron Diffraction.

Course Materials: Lecture notes

Instructors: Dr. Maddalena Pedio

Short curriculum

Dr. Maddalena Pedio is Senior Scientist at the TASC-INFM national laboratory in Trieste. She is scientific coordinator of the laboratory Inverse Photoemission and electron Spectroscopies at TASC and is the local responsible of the BEAR-INFM beamline at the ELETTRA synchrotron. The Dr. M. Pedio research activity is focussed on fundamental aspects of condensed matter, as well as on the use of electron spectroscopies on materials and surface science performed both in laboratory apparata and synchrotron radiation facilities. Local structure determination and electronic properties of low dimensional systems are the two dominant themes in much of her research. She has being responsible of several national and international projects. M. Pedio investigated Photoemission and X-ray optical absorption and Inverse Photoemission (Empty electronic states) in condensed matter, both experimentally and theoretically for the application, modelisation and data analysis of absorption spectroscopies (XAFS) and Photoelectron diffraction with synchrotron radiation for condensed matter studies, in both ordered and disordered materials. Moreover she performed many applications of core level shift analysis by high resolution photoemission (ARUPS and surface photoelectron diffraction) and inverse photoemission in surface and interface characterization. The dominant topics are studies on clean surfaces (elemental and III-V semiconductors, metals) interface formation and chemisorption of low Z elements on surfaces mainly bi and poly atomic molecules, fullerenes interacting with ordered surfaces. Recently she worked on development of surface treatment/growth processes of SiC materials expecially on the growth of SiC thin film by carburization of Si surfaces during fullerene deposition. On the above topics, Dr. Pedio has about 75 original publications in JCR journals and over 100 presentations at International Conferences.

Questions? pedio@tasc.infm.it