Transmission Electron Microscopy: A Powerful and Novel Scientific Technique with Nanoscale Resolution for Characterization of Materials

Abstract

The electron microscopy has brought a revolution in the field of nanotechnology. Various electron microscopy techniques with unique possibilities are used to study morphology, topography, structures and different phases present in the materials. Transmission electron microscope (TEM) is a remarkable scientific tool for the imaging of materials at nanoscale. Ruska and Knoll invented the first TEM consisted of only two electromagnetic lenses for which Ruska got the Nobel Prize. As a result of this invention, it was realized that such lenses are capable to get magnified images at nanoscales. Later on in 1970, the best electron microscopes achieved the resolution of 3.5 Å with several technical improvements and optimizations. This achievement could resolve many columns of metal atoms such as oxide structures. The high resolution of sub-Å has been achieved with the use of advanced aberrations-corrected lenses. The modern TEM’s are capable of attaining resolution of 1 Å at around 300 kV or even less than it can be achieved by using high accelerated energy of electrons. The high-resolution transmission electron microscopes (HRTEM) with high energy and spatial resolution provide the deep insight into almost all the atomic structures. The most important feature of TEM is that it works in both real and reciprocal space. This makes it a unique technique for imaging nanostructures. All samples must be prepared before TEM analysis in order to obtain accurate results. The sample should be very thin and have thickness around 100 nm so that the interaction with electrons should be weak. Thus, the high accelerated electron beam cannot damage the sample. The sample preparation technique for biological and non-biological materials is different. TEM has many applications and one can easily find out the structure, particle size, particle size distribution, elemental compositions and particle shape under observation using it. This technique indeed proved a boon for nanostructures analysis.