Artenum Innovative Solutions

1 Schedule

Here is a link to our schedule: [../files/schema?action=download|FYST20-schedule] (last update: 13th March 2012).\\

1 Meetings and instructions

__Start meeting, Monday, 16th January 2012__\\

Some documents from the start meeting:\\

    *  [../files/schema?action=download|Schedule]
    * Report writing: what is allowed - what is not?
    * [../files/FragorIntromote?action=download|Introductory questions]

~~Information~~
* Preliminary time for experiment at MAXlab is booked week 4:   \\
\\
Until the meeting on Tuesday please read the article on [http://dx.doi.org/10.1039/b509853j|NEXAFS by G. Hähner].\\

__Thuesday, 17th January 2012__\\

The time for experiment week 4 is now fixed: ~~ Wedneday at 13h00 at the MAXlab's main entrance ~~ \\

1  I - Spectroscopy : An experimental observation

__Thuesday, 17th January 2012__\\
First we discussed from a phenomenological point of view what is spectroscopy and what are the experimental signatures in atomic, molecular and solid state physics. The powerpoint presentation can be found [../files/Spektroskopiintro_pdf?action=download|here]. Preliminary discussion in groups with the [../files/QuestionsXPSXASintro_pdf?action=download|question sheet ] is started. We will continue next Friday, 18th January.\\

Here is the [../files/HandIn1_pdf?action=download|first hand-in problem].

__Friday, 18th January 2012__\\
First, we continued the discussion on molecular and solid state physics about the shell model and orbitals. It will be finished next Tuesday, 24th January. In the meantime you can discuss x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) in groups. Please read also the first part of the [../files/InteractionRadiationMatter?action=download|compendium on the interaction of matter and light] - try to get to page 25 .\\

Finally we presented how to write a report, prepare and give a presentation. The requirements for the report and oral presentation can be found  [../files/Projekt_presentation_pdf?action=download|here]. The file containing suggestions for subjects is [../files/Projektanvisningar_pdf?action=download|here].

__Tuesday, 24th January 2012__\\
We finished the first question sheet and discussed from a phenomenological point of view Auger electron, orbitals vs electronic configuration, XPS and XAS.\\

__Wednesday, 25th January 2012__\\
[../files/MAXlab_zip?action=download|Here, you download MAXlab's data files (zip format)]. Try to write your report following the questions:
1. What are the important elements and properties of a soft x-ray beamline? Sketch a soft x-ray beamline such as we've used in the experiment and explain your sketch.
1. Explain what you see in the undulator spectra. NiO_003 should be explained in quite some detail (reasons for the observed structure?).
1. How does a synchrotron-based soft x-ray photoelectron spectroscopy experiment work? What are the important instrumental elements? What is measured and how? What kind of information content do the spectra have?
1. Explain what you see in the x-ray photoelectron spectra. Assign, to the extent possible all features. Justify your assignment.
If you have any problem with the zip file [../material|download directly from here]

1 II - Light Interaction

__Tuesday, 24th January 2012__\\
We looked at the interaction of matter with light using the compendium. In particular, we discuss the main lines to derive the mathematical formulation of the Hamiltonian for a particle in an electromagnetic field. Please, try to have a closer look at the compendium and the [../files/DiskussionsfragorLjusMateria_pdf?action=download|question sheet] for the next lecture.\\

__Thursday, 26th January 2012__\\
~~Information~~
* Lecture at 14h00 room L208 

A summary of the mathematical derivation of the Hamiltonian for a particle in an electromagnetic field is given.\\

We continued the lecture by presenting the different approximation done to treat the interaction of bound electrons with an electromagnetic field. The respective weight of the terms as a function of the wavelength (photon energy from IR to X-rays) was discussed. We conceptually explained how to treat the total Hamiltonian of the system, the role of selection rule, and the time dependent probability of a transition from an initial state |i> to a final state |f>  (Fermi Golden Rule). [../files/Diskussionsbilder_pdf?action=download| Material] to answer the question sheet was provided. A summary of the discussion will be given next lecture with all information required to answer the question sheet.

__Tuesday, 31rst January 2012__\\ 
~~Information~~
* New schedule: Until the end of the term, lectures on Thursday will be  at 14.00 room L208 

First we discuss the interaction of the photon with matter.  Reminders on quantum mechanic algebra was given to derive the matrix element of three type of transitions: dipole electric, quadrupole electric, and dipole magnetic. Finally we explained the foundation of selection rules for a single electron.\\

1 III - Atoms

__Tuesday, 31rst January 2012__\\ 
We introduced the concept of the central field theory to deals with atoms many-electron atoms. We underlined the analogy with hydrogen atom and the evoked the approximations of this method. The presentation can be found [../files/Spektro-Atom_pdf?action=download|here] and the reading instruction for the next lecture [../files/Reading_instruction_pdf?action=download|here].

__Thursday, 2nd February 2012__\\ 
~~Information~~
* Lecture at 14.00 room L208 

We discussed in details the central field theory, called also independent particle model, and presented how the interactions within the atom (spin-orbit interaction and "non central" electrostatic interaction) were affecting the fine structure, leading thus to different coupling scheme LS-coupling and jj-coupling.  Example for two electrons system was given to illustrate the role of the Pauli principle in the construction of the total electronic wave function and to remind how one can determine the different fine structure terms. 

__Thuesday, 8th February 2012__\\ 
During the lecture we essentially discussed the content of the [http://iopscience.iop.org/0034-4885/55/9/003| V. Schmidt] review dealing with the photo-ionization dynamics of rare gas. We introduced the general concept to work beyond the independent particle model and their consequences - mainly interference effects and multi-electron excitation. Finally we presented our observables (various type of cross section) and "standard" experimental signatures that you may have already discussed during your experiment at MAXlab: decrease of the cross section as function of the photon energy, cooper minimum and shake-up. 

Download the [../files/HandIn2_pdf?action=download| second hand-in exercise], and the updated [../files/Spektro-Atom_pdf?action=download|presentation]

__Tuesday, 21rst February 2012__\\ 
During the lecture we went through the hand-in exercises.\\

1 IV - From Molecules to complex matter

__Thuesday, 8th February 2012__\\ 
Toward the end of the lecture, Stacey gave a short introduction to molecular physics. The compendium can be found [../files/Molecules_pdf?action=download|here].

__Thursday, 15th February 2012__\\ 
All you need (or almost) for the CO-project can be found  [../files/CO_project_instructions_zip?action=download| here]. \ 

__Thursday, 23rd February 2012__\\ 
We went through different types of bonding in different clusters, tried to see what kind of information one can get using electron spectroscopy on clusters, and what the advantages of synchrotron radiation as an ionization tool were. We looked at several examples of valence photoelectron spectroscopy studies on size-selected metal clusters, when the transition to metallicity was demonstrated. We looked at what one can learn from core-level photoelectron spectroscopy in general, and on inert gas clusters in particular. The presentation can be found [../files/SPectroscopy_on_Clusters_pdf?action=download| here]

1 V - Surface science

__Tuesday, 28th February 2012__\\ 
~~Information~~
* New schedule. H322 on Thursday download the new version
* The first oral presentation cannot be the 15th of March. 
* Please hand in the CO-project!

The aim of the next couple of lectures is to link together the quantum description of solids with experimental tools for studying solid materials. Focus will be on angle-resolved photoemission spectroscopy, since it can be used to directly image the electronic structure of solids. If there is enough time we will also look into core level spectroscopy and possible other methods.

The aim of today's lecture was to understand where some of the basic properties of the electronic structure of crystalline solids come from. To this end, we considered single, double, and triple potential wells (where the double and triple well actually are the simplest possible quantum model for di- and triatomic molecules). We then considered the case of 10^23 (i.e. an infinite number) potential wells as a model for a solid, and already from this very much simplified model one can deduce the formation of bands and gaps in the electronic structre. From a consideration of an electron in a one-dimensional chain of atoms we saw that the opening of gaps is related to Bragg diffraction inside the crystal and the formation of standing waves. At the gaps there exist states with two different energies, corresponding to different standing waves.

* Suitable reading is e.g. Charles Kittel, Introduction to Solid State Physics, chapter 7 or Davd W. Snoke, Solid State Physics - Essential Concepts, chapter 1.

On Thursday we will continue with considering the so-called Kronig-Penney model and will then look at how angle-resolved photoemission can be used to study the electronic structure of solids. In this context we need to discuss the process of photoemission in some more detail, and there you should read the following text until Thursday:

* S. Hüfner, Photoelectron Spectroscopy, 3rd edition, Springer, Berlin, Heidelberg, 2003, pp. 347 - 357.

Until Tuesday next week you should also read the following paper:

* [http://dx.doi.or/10.1126/science.1130681|Taisuke Otha et al., Science 313 (2006) 951] 

If you could not attend the lecture you're welcome (required) to fetch a copy of the text of Hüfner from me.

__Thursday, 1rst March 2012__\\ 
We continued with the quantum description of solids and had a look at how a solid's band structure arises from the periodicity of the material. To this purpose we introduce the one dimensional Kronig-Penney model. The model also shows that the electron wave function has a form, which is adapted to the symmetry of the crystal. Even in a three dimensional crystal the wave function has the same form, the so-called Bloch form.

Further, we reminded ourselves of reciprocal space and reciprocal lattice vectors, and we discussed the properties of electronic bands at the Brillouin zone boundaries and in the centre of the first Brillouin zone.

__Tuesday, 6 March 2012__\\
As a last theory topic before moving to experiment we had a look at the electron effective mass in a solid (non-relativistic description).

Then we introduced Angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) which today is the standard tool for bandstructure measurement, i.e. the measurement of E(k). To get a better understanding we read and discussed the article by Jo Stöhr on an early ARUPS measurement on the Cu(110) surface:

[http://prola.aps.org/abstract/PRB/v17/i2/p587_1|J. Stöhr et al., Phys. Rev. B 17 (1978) 587] .

On Thursday we will finish off the discussion of ARUPS by a discussion of the article by Ohta et al. If there is any time left we will discuss some aspect of core level spectroscopy on solid materials.

__Thursday, 8 March 2012__\\
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