SYNCHROTRON EXPERIMENTS

Members
N.N. Former Members:

Members

Former Members:

Topics
Alignment of metal-organic molecules at the interface to metal and semiconductor substrates Analysis of stoichiometry and chemical environments in adsorbants Optical characterisation of high bandgap materials and very thin films of magnetic molecules

Equipment
Experiments are performed at BESSY at the [beamlines U125/2 NIM and the] Russian German Beamline (RGBL-PGM), and at the Physikalisch Technische Bundesanstalt (PTB). The semiconductor physics group regularly conducts research stays at the synchrotron facility BESSY II. The activities concentrate on [VUV ellipsometry and] X-ray absorption spectroscopy. [The vacuum ultra violet ellipsometry extends the accessible spectral range of ellipsometry from 0.73 to 5.03 eV which can be measured in the Chemnitz laboratories towards the high energy range up to 10 eV. This allows the characterisation of high bandgap materials and thin films of organic compounds with dominant absorption bands above 5 eV. These experiments are currently performed at the U125/2 NIM beamline with the support of the ISAS institute.] The X-ray absorption spectroscopy (XAS) or, more precise, the near edge X-ray absorption fine structure (NEXAFS) measurements allow the determination of the alignment of molecules in very thin films (< a few nm). Whereas the techniques available in Chemnitz (Raman and infrared spectroscopy, ellipsometry, magneto-optical Kerr effect spectroscopy) provide access to the average molecular orientation in films of thicknesses above 10 nm, the NEXAFS technique enables the investigation of the film strucure in the very beginning of the film growth. The experiments are performed at the Russian-German-Beamline which also provides X-ray photoemission capabilities.

Equipment

Experiments are performed at BESSY at the [beamlines U125/2 NIM and the] Russian German Beamline (RGBL-PGM), and at the Physikalisch Technische Bundesanstalt (PTB).
The semiconductor physics group regularly conducts research stays at the synchrotron facility BESSY II. The activities concentrate on [VUV ellipsometry and] X-ray absorption spectroscopy.

[The vacuum ultra violet ellipsometry extends the accessible spectral range of ellipsometry from 0.73 to 5.03 eV which can be measured in the Chemnitz laboratories towards the high energy range up to 10 eV. This allows the characterisation of high bandgap materials and thin films of organic compounds with dominant absorption bands above 5 eV. These experiments are currently performed at the U125/2 NIM beamline with the support of the ISAS institute.]

The X-ray absorption spectroscopy (XAS) or, more precise, the near edge X-ray absorption fine structure (NEXAFS) measurements allow the determination of the alignment of molecules in very thin films (< a few nm). Whereas the techniques available in Chemnitz (Raman and infrared spectroscopy, ellipsometry, magneto-optical Kerr effect spectroscopy) provide access to the average molecular orientation in films of thicknesses above 10 nm, the NEXAFS technique enables the investigation of the film strucure in the very beginning of the film growth. The experiments are performed at the Russian-German-Beamline which also provides X-ray photoemission capabilities.

Examples

From the dependence of the total electron yield on the angle of incidence the tilt angle of highly symmetric molecules (here cobalt-phthalocyanine) on the substrate can be determined.