79109 - X-Ray Techniques

Learning outcomes

The course provides educational experiences which challenge students to: be aware of the characteristics of X-ray methods of analysis (X-ray absorption and emission spectroscopy) as a strong structural tool: advantages, disadvantages, and applicability in the applied chemistry; be aware of the electronic information contained in the XAFS spectrum and its applicability; perform a preliminary XAS data reduction; be aware of the most recent core-level spectroscopy analytical techniques for solid and solutions; to design spectroscopic in-situ experiments.

Course contents

Prerequisites

To successfully attend this class, the student should know the basic of x-rays and x-ray diffraction (course: “X-Ray Diffraction” at the University of Lille)

 

Content

Introduction to the course.

X-rays: origin and generation. X-ray absorption coefficient and mass absorption coefficient. Calculations and examples on mass absorption coefficient. Decay of the core-hole: x-ray Fluorescence and Auger effect.

X-ray absorption spectroscopy and the acronyms XANES, EXAFS, SEXAFS, NEXAFS. Theory: The EXAFS equation and the key approximations: one electron, plane wave, and K-threshold. Muffin-Tin and many body effects. Debye-Waller EXAFS factor and disorder.

X-Ray emission spectroscopy. Resonant Inelastic X-ray Scattering.

Experimental methods for Absorption and Emission. Synchrotron radiation. XAS Spectroelectrochemistry and cells for in-situ measurements. In situ studies.

Data Analysis. XANES calculations ad EXAFS fittings. Primary data reduction: extraction of the (k) and Fourier Transformation. Data analysis using fitting approach. Chemometry for spectroscopy. Use of Multivariate Curve Resolution - Alternating Least Square (MCR-ALS) algorithm for the analysis of operandodata collection.

Applications in the field of solution chemistry, surfaces, catalysis, batteries, inorganic and biological materials.

 

Readings/Bibliography

G. Bunker, “Introduction to XAFS” Cambridge University Press, 2010. ISBN: 978-0-521-76775-0

Marco Giorgetti and Lorenzo Stievano (2017). X-Ray Absorption Spectroscopy Study of Battery Materials, X-ray Characterization of Nanostructured Energy Materials by Synchrotron Radiation, Dr. Mehdi Khodaei (Ed.), InTech, DOI: 10.5772/66868. Available from: https://www.intechopen.com/books/x-ray-characterization-of-nanostructured-energy-materials-by-synchrotron-radiation/x-ray-absorption-spectroscopy-study-of-battery-materials

Teaching methods

The course describes the potentiality of both X-Ray Absorption and X-Ray Emission as an electronic and structural tools for the study of the condensed, crystalline, and amorphous phase. Front lectures and exercitation will be the offered with several examples concerning modern data analysis and interpretation of spectra.

Assessment methods

The final examination will determine the level reached by the student in the objectives set out in the "Learning outcomes”. The assessment of the learning consists in oral presentation of the students on a selected research topics learned during the course. The student tells the teacher a topic chosen from those discussed in class one week before the examination and prepare a power point presentation with a maximum of 15 slides according to materials deduced using 2-3 papers.

During the oral exam, the student explain the article, also making use of a specially prepared presentation. Then a discussion follows on the presented concepts and the theme of the article inspires to discuss the basic concepts common to all the topics covered in class.

The final assessment takes into account both the exposure (15 points) and the ability to discuss the general concepts (18 points). The honor (cum laude) is reached with 33 points.

Teaching tools

Lecture slides and other material useful for exam preparation is made available to the student electronically via the Internet. To get the teaching material the student must be connected to the site : http://campus.unibo.it/. Username and password are reserved for students enrolled at the University of Bologna and will be provided by the teacher.

Office hours

See the website of Marco Giorgetti