![]() It must also have an acceptable number of image pixels such that any uncertainties associated with the measurements are minimized during image processing. 3 A good image must exhibit good levels of brightness and contrast and must provide a sufficient number of particles with a good resolution. One of the most important steps for characterizing materials using electron microscopy is acquiring images that are interpretable and which provide accurate information about the sample under study. For direct current (dc) sputtering, coating metals (Au) or alloys (Au-Pd, Pt-Pd) are used as a target. A carbon wire or belt is an important material used in thermal evaporation: when heated to its vaporization temperature using a high electric current in a vacuum, it evaporates rapidly into a monoatomic state. The sample's conductive layer is usually deposited using either thermal evaporation or sputter coating. In the latter case, however, the improvement to the charge effect on the surface is accompanied by a worsened resolution. increasing its conductivity by infusing it with conducting compounds or performing the analysis in an environmental scanning electron microscope for samples that exhibit humidity and/or are uncoated). carbon or metal coating such as silver, gold, platinum, chromium, aluminum, or gold-palladium alloys), and (ii) modification of the environment in which the specimen is being studied (i.e. According to Goldstein et al., 2 two main procedures can be used to avoid or minimize the effect of surface charge: (i) modification of the specimen by increasing its surface conductivity through a coating with a thin layer of a conductive material (e.g. In some extreme cases, the sample may acquire sufficient charge on surface to significantly decelerate the primary beam. In addition, the primary beam also may cause thermal and radiation damage, thus leading to the deterioration of the sample. A conductive layer is usually necessary to reduce the effect of the electric charge on the surface caused by the interaction between the electron beam and the sample, which can result in image distortion. 1 Non-conductive or poorly conducting materials such as pharmaceuticals, some ceramics, polymers, glass, and organic materials may need surface treatment before they can be analyzed under optimal conditions by an electron microscope. Particle size distribution (PSD) and surface morphological characteristics are the most important analyses when studying nanoparticles, and the scanning electron microscope is very useful for these tasks. Palavras-chave: particle size distribution near-spherical polymer nanoparticles gold coating carbon deposition scanning electron microscopy. The study also revealed two main effects of the conductive coating: changes to topography and an increase in mean particle diameter. Results showed that the method proposed in this work produces mean diameter values in accordance with NIST-traceable near-spherical polymer nanospheres for the sample without coating. The images were collected using a field emission scanning electron microscope and then processed using the ImageJ program. The effect on the diameter of near-spherical polymer nanospheres between 20 and 100 nm (mean of 60 nm) when samples were coated by a conducting layer (such as gold or carbon) was also evaluated. This study shows the results of a particle counting procedure that relies on a fully automated method that was found to improve the reproducibility of the measurement. The process of counting particles is typically performed manually, which requires both more time and a higher standard deviation than automatic methods. The best technique for determining particle size distribution is scanning electron microscopy. ![]() It is also an important parameter for characterizing nanoparticles. The determination of particle size distribution is an important parameter for controlling industrial processes, particularly in the field of pharmaceuticals. Publicado em: Endereço para correspondência Instituto de Química, Universidade Estadual de São Paulo, 14800-060 Araraquara - SP, Brasil Development of an automated method to perform a quantitative study of particle size distribution and the effect of a conductive layer in scanning electron microscopy
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