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Spectroscopy

  • What we do

    We perform in-situ and real-time chemical, electronic and optical characterization of materials under different conditions, e.g. to identify and map different phases.

  • What we do

    We perform in-situ and real-time chemical, electronic and optical characterization of materials under different conditions, e.g. to identify and map different phases.

Spectroscopy

The kinetic energy of electrons emitted from atomic core levels after x-ray photo absorption is characteristic of the respective element and its chemical state, giving rise to individual spectral lines which can be used, e.g., to distinguish different oxidation states with XPS. Combined chemical and structural information are contained in so-called LEEM-IV measurements, where, in a separate experimental setup, low-energy electron reflectivity is recorded as a function of the incident electron energy. Such chemical and structural surface phases can be identified with a lateral resolution of a few tens of micrometers.

Complementary, the vibrational and structural properties of samples can be investigated using Raman and circular dichroism spectroscopy setups.

What kind of result do I get?

With XPS and LEEM both the chemical composition as well as the local structure and morphology of samples can be addressed. Since both techniques employ electrons with rather low energy, the information depth is restricted to a few atomic layers, and a decent electrical conductivity of the samples is required as well as ultra-high vacuum compatibility. Spectra and images can also be taken at elevated temperatures as well as during gas dosing (up to 10-4 mbar) to study changes of the chemistry, structure, and morphology during annealing or interaction with gases.

The local bonding geometry can be revealed with vibrational (Raman) spectroscopy. Circular dichroism spectroscopy (CDS) allows for the investigation of chiral structures, e.g. biomolecules adsorbed at interfaces. Both methods, Raman and CDS, are less surface sensitive than the electron-based methods of XPS and LEEM, and can be obtained from a wider class of specimens (e.g. insulators, non-UHV compatible materials.)

Principal Investigator

Prof. Dr. Jens Falta

Instrument Manager

Dr. Guilherme Dalla Lana Semione
University of Bremen
MAPEX Core Facility for Materials Analytics
TAB Building, Room 3.34
Am Fallturm 1, D-28359 Bremen
E-Mail: Instrument manager

Our key instruments

XPS chamber

Omicron DAR 400 + EA 125
X-ray photoemission spectrometer

  • Twin Al/Mg anode, 125 mm hemispherical analyzer, 7-channel parallel detection unit
  • UHV system additionally equipped with low-energy electron diffraction (LEED), scanning tunneling microscope (STM), and evaporation ports
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LEEM chamber

SPE-LEEM Elmitec
Spectroscopic low-energy electron microscope

  • Full-field electron microscope with lateral resolution down to 10 nm; diffraction mode for micro-LEED images from selected areas with down to 250 nm in diameter
  • Hemispherical energy analyzer
  • Video rate imaging for real-time investigations, e.g., during material deposition or gas dosing; 100-1800 K temperature range
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Raman spectroscope

Horiba LabRAM Aramis
Raman Spectrometer

  • 532 nm, 633 nm and 785 nm lasers
  • Measurements possible between 78 K and 1773 K
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cd spectrometer

Applied Photophysics Chirascan
Circular dichroism spectrometer

  • Surface and interface characterization
  • (Secondary) structure detection of biomolecules
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More available instruments

Current instrumentation belonging to MAPEX-CF can be found in the Instrument Database of the MAPEX Center for Materials and Processes.

A click on the logo will lead you to the database.
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Spectroscopy|

The morphology of VO2/TiO2(001): terraces, facets, and cracks

Jon-Olaf Krisponeit, Simon Fischer, Sven Esser, Vasily Moshnyaga, Thomas Schmidt, Louis F. J. Piper, Jan Ingo Flege, Jens Falta

Nature Scientific Reports (2020) 10, 22374

https://doi.org/10.1038/s41598-020-78584-9

Vanadium dioxide (VO2) features a pronounced, thermally-driven metal-to-insulator…

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LEEm picture
Spectroscopy|

Growth and structure of ultrathin praseodymium oxide layers on ruthenium (0001)

Jan Höcker, Jon-Olaf Krisponeit, Julian Cambeis, Alexei Zakharov, Yuran Niu, Gang Wei, Lucio Colombi Ciacchi, Jens Falta, Andreas Schaefer and Jan Ingo Flege 

Physical Chemistry Chemical Physics (2017) 19, 3480-3485

https://doi.org/10.1039/C6CP06853G

The growth, morphology, structure, and…

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xps spectra
Spectroscopy|

Isotropic thin PTCDA films on GaN(0001)

C. Ahrens, J. I. Flege, C. Jaye, D. A. Fischer, T. Schmidt and J. Falta

Journal of Physics: Condensed Matter (2016) 28, 475003

https://doi.org/10.1088/0953-8984/28/47/475003

The growth of 3, 4, 9, 10-perylene tetracarboxylic dianhydride (PTCDA) on the Ga-polar GaN(0 0 0 1) surface has been…

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Spectroscopy|

Controlling the Multiscale Structure of Nanofibrous Fibrinogen Scaffolds for Wound Healing

Karsten Stapelfeldt, Stephani Stamboroski, Irina Walter, Naiana Suter, Thomas Kowalik, Monika Michaelis and Dorothea Brüggemann

Nano Letters (2019) 19, 6554–6563

https://doi.org/10.1021/acs.nanolett.9b02798

As a key player in blood coagulation and tissue repair, fibrinogen has gained increasing…

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Aktualisiert von: MAPEX-CF