ABSTRACT
New commercially available electron microscopes accessories permit an easy Electron Energy Loss Spectroscopy (EELS) analysis with good sensitivity and accuracy. But EELS still remains a complex method whose potentiality is seldomly completely exploited. Beside nanoanalysis, several possibilities of producing new images are described. The scattering power image for beam-sensitive specimens, the separation of elastic and inelastic components and the mean free path ratio are among these possibilities. Mass thickness measurement for example can benefit a lot from these techniques. In the nanoanalysis field, a particular emphasis is given to the spectrum-image acquisition method. This method is very convenient to obtain chemical maps of different elements from the same area of the specimen. The background effects and the errors in its estimation are often underevaluated. This can provoke spurious effects in chemical maps. The spectrum-image offers several ways to avoid this inconveniency.
Subject(s)
Microscopy, Electron/methods , Spectrum Analysis/methods , Animals , Bone and Bones/ultrastructure , Elements , Microscopy, Electron/instrumentation , Microscopy, Electron, Scanning Transmission/instrumentation , Microscopy, Electron, Scanning Transmission/methods , Rats , Signal Processing, Computer-Assisted , Spectrum Analysis/instrumentation , Tissue DistributionABSTRACT
With its specific design for recording simultaneous signals, the scanning transmission electron microscope (STEM) offers unique imaging capabilities. In order to use them fruitfully, we have implemented, on a VG STEM equipped with a magnetic spectrometer, home-made detectors for recording multisignal images. This paper first describes a method developed for the quantitative evaluation of detection efficiency of all data-acquisition channels involved in these multisignal images. At this stage, new imaging modes become accessible, which can be classified following their specificity and sensitivity; scattering power image, elastic and inelastic images mean free path ratio images. Original applications encountered in the biological as well as in the materials science fields illustrate the possibilities of these various approaches, which can be of great interest in quantitative microscopy, analytical imaging or low-dose observation.
