In Search of Nanostructures: EU funds Research and Development of Correlative Microscopy Techniques
German and Czech microscope specialists jointly develop a new analytical instrument.
Nanostructures appear almost everywhere in our environment: In nature nanostructures serve as protection from dirt for plant leaves or provide adhesion for animals on slick surfaces. In developing modern technologies the advantages of nanostructures are more and more recognized and used, e.g. to create functional surfaces or to manufacture ultra-thin, conductive materials. The research and development of nanostructures requires analysis methods that provide detailed information about the investigated sample.
Specialists from Germany, the Czech Republic, and Switzerland are jointly advancing novel, correlative microscope techniques to provide new opportunities for the detailed analysis of nanostructures. Their work is part of the EU-funded project UnivSEM, which supports the development of supplementary analysis tools for scanning electron microscopes (SEM). UnivSEM receives funding from the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement n° 280566. The funding period is from April 2012 to May 2015.
As part of the UnivSEM project, TESCAN ORSAY HOLDING, a multinational company experienced in charged particle optics and WITec, a distinguished German specialist in Raman and scanning probe microscopy, successfully introduced a correlative microscopy technique which combines electron microscopy with Raman microscopy. The resulting RISE (Raman Imaging and Scanning Electron) Microscopy technique enables for the first time ultra-structural and chemical imaging with one microscope. The electron microscope allows the analysis of surface structures in the nanometer range. With confocal Raman microscopy, a common spectroscopic method for chemical imaging, information about the molecular compounds of a sample can be obtained. “The interest in correlative microscopy techniques is constantly growing in recent years.” explains Dr. Joachim Koenen, CEO at WITec “Reasons include the increasing requirements for analytical methods in regard to the most detailed and comprehensive sample investigations. An innovative development such as the RISE Microscope, which combines the advantages of these techniques within one system, is therefore more in demand than ever.”
For the investigation of a sample with correlative RISE Microscopy the sample is positioned on a scan stage within the vacuum chamber of the microscope. Both applied RISE techniques are non-destructive and therefore do not require any staining or other preparation prior to the measurement procedure. First the sample is imaged in scanning electron microscope (SEM) mode in order to analyze the surface. The SEM image reveals tiny structures in the nanometer range. After the initial measurement, the scan stage automatically transfers the sample and precisely re-positions it for confocal Raman imaging. The identical sample area is then recorded in Raman imaging mode. The Raman image contains the information of the chemical components, their molecular compounds and their distribution. A specifically developed software correlates the SEM and the Raman images and overlays them.
Feasible fields of application for RISE Microscopy technique include nanotechnology and materials research, in which RISE Microscopy can, for example, facilitate the development and manufacture of new materials and electronic devices. A current example of a RISE application is graphene research. Graphene is an ultra-thin conductive material consisting of carbon atoms that is the subject of intense study at the moment. Another sector that has a huge demand for combined analytic techniques such as RISE Microscopy is the biomedical research and pharmaceutical industry.