Equipment built by German scientists can be used to study processes at interfaces with great accuracy. In an article published recently in ChemPhysChem, Hans Joachim Freund and co-workers of the Fritz-Haber-Institut in Berlin describe the advancement of four experimental techniques developed in their lab to investigate nanoscopic systems.
By combining photon scanning tunneling microscopy, aberration-corrected low-energy electron microscopy coupled to photoelectron emission microscopy, microcalorimetry, and electron-spin resonance spectroscopy, unique information on the relationship between geometric structure and properties is obtained. The methods can be applied to solve fundamental problems in surface science and to study interesting systems -particularly in the field of catalysis- which would otherwise be difficult (or impossible) to address.
“Catalysis happens at interfaces and experimental techniques are desperately needed to provide information on those systems”, says Freund who is interested in understanding disperse metal and oxide catalysts at the atomic scale. According to the researcher, appropriate samples in this field are very complex so that a combination of techniques is generally required to achieve a complete picture and avoid overestimating individual results. This led him and his colleagues to design new instruments to characterize their systems.
The first method developed by the German team could overcome one of the main disadvantages of scanning probe techniques, namely, their inherent chemical insensitivity, by detecting the fluorescence signal generated by locally exciting the surface with electrons from the tip. The new technique is called photon scanning tunneling microscopy (PSTM) and has been used to study the optical characteristics of metal particles and investigate defect structures in oxide surfaces. Additionally, the researchers are working on a new aberration-corrected instrument for low-energy electron microscopy (LEEM) and photoelectron emission microscopy (PEEM), which will hopefully allow them to investigate single supported nanocatalysts. Freund and co-workers have also built a highly sensitive microcalorimeter that can be used to measure temperature-dependent heats of adsorption on nanoparticle ensembles with aggregate sizes of about a hundred atoms. The fourth technique, called electron-spin resonance (ESR) spectroscopy, can be applied to study particle ensembles and may provide interesting information that is out of reach for other methods, the authors say.
Author: Hans Joachim Freund, Fritz-Haber Institut der Max-Planck Gesellschaft, Berlin (Germany), http://www.fhi-berlin.mpg.de/cp/hjf.epl
Title: Innovative Measurement Techniques in Surface Science
ChemPhysChem 2011, 12, No. 1, Permalink to the article: http://dx.doi.org/10.1002/cphc.201000812
How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH
A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology