WITec and Tescan Orsay Holding have launched the RISE Microscope for Correlative Raman-SEM Imaging at Analytica 2014.
RISE Microscopy is a technique which combines confocal Raman Imaging and Scanning Electron (RISE) Microscopy (SEM) within one integrated microscope system.
It is the first machine to enable acquisition of SEM and Raman images from the same sample area and the correlation of ultra-structural and chemical information with one microscope system, claim the firms.
SEM and Raman are high-resolution imaging techniques with sub-nanometer and diffraction limited 200-300 nanometer resolution, respectively.
WITec said it could be used in the food industry as part of imaging and analysis of ingredients.
Dr Olaf Hollricher, managing director research and development at WITec, said SEM is widely used but it doesn’t give chemical information.
“Scanning electron microscope is used for easy imaging of samples up to high resolution down to nanometers but the problem is you don’t get chemical information in the SEM,” he told FoodQualityNews.com at Analytica trade show in Munich.
“With the confocal Raman microscope you get chemical information and combining these two techniques could be very interesting for a lot of applications including the food industry.”
It provides all functions and features of a stand-alone SEM and a confocal Raman microscope.
Electron microscopy is used to visualize the sample surface structures in the nanometer range; confocal Raman imaging is a spectroscopic method for the detection of chemical and molecular components of a sample.
Hollricher said that Raman for single spectra was already available but had limitations.
“The problem with single spectra is of course you get the chemical information but only from a single point and the problem in SEM, you don’t see where your spectrum exactly comes from, you have to assume it comes from this point but depending on the calibration it can be several micrometres off and you only have a single point.
“That is a big problem because you have an image and then a cross and you assume the spectrum or the component is there but you don’t know exactly, with this machine you can get an image of the distribution of the different components and this you can overlay and then you can immediately see where which components are.”
How it works
The sample is positioned on a scan stage within the vacuum chamber of the microscope.
As both techniques are non-destructive, there is no requirement for staining or other preparation prior to measurement.
The SEM image reveals tiny structures in the nanometer range and the Raman image contains the information of the chemical components, their molecular compounds and their distribution.
After the initial measurement, the scan stage automatically transfers the sample and re-positions it for confocal Raman imaging.
The SEM image on the computer gives a high resolution and after the Raman measurement there is an additional image which gives the distribution of different components in the sample, said Hollricher.
“You can overlay these two images, the SEM is typically a black and white image, which gives black and white contrast and you can colour code the different components in your sample in the Raman image so that when you overlay them you see the different components as different colours.”
The SEM image typically takes seconds or minutes and the Raman image can take about 10 minutes.
“The analysis of the images can take longer time but it depends on how strong the signal is and the depth of the problem you are analyzing,” he added.
WITec and TESCAN developed the RISE Microscope under the framework of the UnivSEM project.
The EU-funded project, until May 2015, aims to advance correlative microscope techniques to provide opportunities for the detailed analysis of nanostructures.