Vadym Prysiazhnyi Specially for Student seminary, Brno, XX April, 2011.

Vadym Prysiazhnyi

Specially for Student seminary,Brno, XX April, 2011

History Work principle Measuring procedure Data evaluation Final remarks

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1914 : Robinson and Rawlinson studied photoemission from X-ray irradiated gold and observed energy distribution of electron produced.

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1921: The Nobel Prize in Physics 1921 was awarded to Albert Einstein "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect".

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1924: The Nobel Prize in Physics 1924 was awarded to Manne Siegbahn "for his discoveries and research in the field of X-ray spectroscopy".

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1951: Kai Siegbahn (son) developed theory of Electron Spectroscopy for Chemical Analysis (ESCA), i.e. XPS.

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1951: Kai Siegbahn (son) developed theory of Electron Spectroscopy for Chemical Analysis (ESCA), i.e. XPS.

1981: The Nobel Prize in Physics 1981 was divided, one half jointly to Nicolaas Bloembergen and Arthur Leonard Schawlow "for their contribution to the development of laser spectroscopy" and the other half to Kai M. Siegbahn "for his contribution to the development of high-resolution electron spectroscopy".

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XPS basicsHemispherical detector

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• Hemispherical electron analyser (VG MKII)

• X-ray source: unmonochromatized Al Ka (energy 1,486.6 eV)

• base pressure in the analysis better than 1.9 10-10 mbar

• energy resolution of 1.2 eV

• Lock-in chamber for fast sample transfer

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X-ray source

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X-ray source

Monochromatization by using mirrors for X-ray

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X-ray source

Monochromatization by using mirrors for X-ray

more “optics” => more lossesmore losses => more power need to generatemore power need to generate => problems with cooling

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Measuring the overall spectra

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Determine the elements

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Determine the elements

Measure each peak separately for precise analysis

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Photoelectric effectKE = hν - BE

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SMALL PROBLEM!!!SMALL PROBLEM!!!

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SMALL PROBLEM!!!SMALL PROBLEM!!!

MAYBE BIG PROBLEM!!! (if MAYBE BIG PROBLEM!!! (if there is unknown material there is unknown material with a lot of peaks)with a lot of peaks)Chemical shiftsChemical shifts

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Remember about losses distribution

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Subtracting backgrounds

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Calculating the relative atomic ration between elements

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Determining the bonds and chemical state of material

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Determining the bonds and chemical state of material

If equipment good enough, recalculating intensities into real thicknesses

1. How to choose the correct background?

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2. Recalculation to real thicknesses.

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2. Recalculation to real thicknesses.

3. Resolution problem

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What we can do Difficulties/

Few nanometers sensitivity

Non-destructive method

Identify all elements (exept of H and He)

Get the information about the chemical and molecular state

Possibility to have lateral and depth profiles

Quantitative determination

Expensive equipment In case of many

elements or need to precise determination analysis become extremely difficult

Sensitivity on the level of 0,1%

We are now here

Scientists…

Office managers,Somewhere there,Or elsewhere

Vadym Prysiazhnyi Specially for Student seminary, Brno, XX April, 2011.

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