The characterization techniques that Ill discuss are including: Scanning electron microscopy (SEM)Transmission electron microscopy (TEM)High- resolution transmission electron microscopy (HRTEM)Atomic force microscopy (AFM)Energy dispersive x-ray spectroscopy (EDS)Ultraviolet-visible spectrometry (UV-vis)Fourier transform infrared spectroscopy (FTIR)Dynamic light scattering (DLS)X-ray diffraction (XRD)And Zeta potential analysisCharacterization is important to ensure that the prepared particles are at the nanoscale. In material science, the term characterization refers to the general and broad processes through which the properties and structure of the material are explored. Characterization helps to determine the composition and structure of materials, and also allows us to assess whether the method was successful or not. Some of the characterization techniques are qualitative, and some other are quantitative. In this lesson, Ill focus on widely used and effective techniques available to characterize nanomaterials. The primary objective of this lesson is to provide a theoretical and practical description of the methods used to characterize a broad range of nanomaterials. I will focus on suitability of the method, sample preparation, and anticipated results. I will also use several examples for characterizing synthesized nanomaterials with each technique. Scanning electron microscopy, often called SEM is a microscope that produces images using electrons instead of visible light. Transmission electron microscopy or TEM is the technique of choice for analysis of specimen internal microstructure and evaluation of nanostructures such as particles, fibers, thin films, and imaging of atoms. This is possible because instead of using light for imaging, we use electrons. EDS gives an overall mapping of the sample by analyzing near-surface elements and estimates the elemental proportion at different positions. EDS is a non-destructive analytical technique. It provides information on the elemental and chemical composition of a sample. EDS essentially allows us to determine what something is made out of. Atomic force microscopy or AFM is a powerful and versatile microscopy technology used to study the samples at a nanoscale. It takes an image in a three-dimensional topography and provides various kinds of surface measurements, meeting the needs of engineers and scientists. Ultraviolet- visible spectroscopy technique consists of a deuterium or tungsten lamp for the ultraviolet and visible region wavelengths respectively, a monochromator, sample and reference beams, and a detector. Fourier transform infrared spectroscopy often called FTIR is used for the identification of organic, inorganic, and polymeric materials utilizing infrared light for scanning the samples. The crystallinity of a sample is determined with the aid of X- ray diffraction or XRD analysis. Beyond the purpose of identification, it can be used to serve additional information. Dynamic light scattering often called DLS, is a non-invasive technique for measuring the size and size distribution of particles typically in the submicron region, and with the latest technology, lower than 1nm. Zeta potential is a measure of the effective electric charge on the nanoparticles surface and quantifies the charge stability of the colloidal particles.
