Electron Microscope PDF

Electron Microscope o Electron microscopy uses an electron beam to create an image of a sample. Because of this an electron microscope has a much greater resolving power than a light microscope and is capable of much higher magnifications (up to 2 million times)....

Electron Microscope o Electron microscopy uses an electron beam to create an image of a sample. Because of this an electron microscope has a much greater resolving power than a light microscope and is capable of much higher magnifications (up to 2 million times). o Discovered by two German scientist, Ernst Ruska and Max Knoll in 1931 as they realized that they could have a greater resolution of specimen's image by utilizing electrons instead of light. o Primarily used to study structures of tissues, cells, organelles, intracellular pathogens and other macromolecular complexes 2 MAIN TYPES OF ELECTRON MICROSCOPES A. TEM (Transmission Electron Microscope) o used to observe finer details of internal structures o specially prepared thin samples are supported on TEM grids o ELECTRON BEAM is passing through the specimen o produces flat images or 2D. How does it work? Transmission Electron Microscopy (TEM) involves transmitting a high-voltage electron beam through an ultra- thin specimen, creating an image based on electron density and structural variations, with resolutions below 1 nanometer. The process begins with an electron gun emitting electrons that pass through a vacuum tube and are focused into a fine beam by an electromagnetic lens. This electron beam then traverses the thin specimen, scattering or hitting a fluorescent screen to form an image where different components are depicted based on their density. Applications: o examine small column of atoms, cancer research, virology, pollution nanotechnology B. SEM (Scanning Electron Microscope) o used to observe the surface structure of microscopic objects o Sample can be in any thickness and is mounted on aluminum stub o Instead of travelling through specimen, the electron beam effectively bounces straight off it o o produces very sharp 3D images How does it work? o Scanning Electron Microscopy (SEM) involves scanning a focused beam of electrons across the surface of a specimen, causing the emission of secondary electrons, backscattered electrons, and X-rays, which are detected to create a three-dimensional image of the surface topography with resolutions typically around 1-10 nanometers. The SEM operates with an electron gun that emits an electron beam directed at the specimen. Electromagnetic coils systematically scan this beam across the specimen's surface, and the reflected electrons are directed to a cathode-ray screen to form an image of the scanned object. Applications: o use for live specimen examination, use for visualization of intracellular changes Difference between TEM and SEM: 1. Principle of Operation: o TEM (Transmission Electron Microscopy): Transmits a beam of electrons through an ultra-thin specimen to form an image based on electron density and structural variations. o SEM (Scanning Electron Microscopy): Scans a focused beam of electrons across the surface of a specimen, detecting secondary and backscattered electrons to form a three-dimensional image of the surface. 2. Image Formation: o TEM: Produces images by detecting electrons that pass through the specimen. o SEM: Produces images by detecting electrons that are reflected off the surface of the specimen. 3. Resolution: o TEM: Can achieve resolutions below 1 nanometer, revealing fine internal structures. o SEM: Typically has resolutions around 1-10 nanometers, suitable for detailed surface topography. 4. Specimen Preparation: o TEM: Requires very thin specimens, often less than 100 nanometers thick. o SEM: Can work with bulkier specimens, as long as they fit within the instrument's chamber. Advantages and Disadvantages: TEM: Advantages: o Extremely high resolution, allowing for detailed internal structural analysis. o Can provide information about crystal structures, morphology, and defects at atomic levels. Disadvantages: o Requires extensive and often challenging specimen preparation. o Limited to very thin samples, which may not represent the bulk material. o More expensive and complex to operate and maintain. SEM: Advantages: o Provides detailed surface topography and composition. o Easier and faster sample preparation compared to TEM.  o Can accommodate larger and bulkier samples. Disadvantages: o Lower resolution compared to TEM. o Primarily provides surface information, not internal structure. o May require coating non-conductive samples with a conductive material. Applications of Electron Microscopy Electron microscopy has a broad range of applications across various scientific fields: Biology and Medicine: -TEM is used to study cellular and subcellular structures, such as organelles and macromolecular complexes, at high resolutions. -SEM is employed to examine the surface morphology of tissues and microorganisms. Electron microscopy also aids in diagnosing diseases by analyzing tissue samples at the microscopic level (Yoshiyama & Shimizu, 2018). Materials Science: -SEM and TEM are crucial in materials science for characterizing the microstructure, composition, and properties of materials. They are used to investigate metals, ceramics, polymers, and nanomaterials, providing insights into their performance and reliability (Williams & Carter, 2009). Nanotechnology: -The development of nanotechnology relies heavily on electron microscopy to visualize and manipulate nanostructures. TEM is essential for studying nanoparticles, nanotubes, and quantum dots, while SEM is used for fabricating and analyzing nanoscale devices (Cao, 2004). Recent Advancements in Electron Microscopy Recent advancements have significantly enhanced the capabilities of electron microscopy: Cryo-Electron Microscopy (Cryo-EM): Cryo-EM has revolutionized structural biology by allowing the visualization of biomolecules in their native state without the need for crystallization. The technique involves rapidly freezing the specimen to preserve its structure and imaging it at cryogenic temperatures. Cryo-EM has led to breakthroughs in understanding the structure and function of complex proteins and viruses (Dubochet et al., 2017). Electron Energy Loss Spectroscopy (EELS): EELS is an advanced analytical technique combined with TEM to study the chemical composition and electronic structure of materials. It provides information on elemental composition, bonding, and electronic transitions, contributing to the development of advanced materials (Egerton, 2016). In-situ Electron Microscopy: In-situ techniques enable the observation of dynamic processes in real-time under various environmental conditions, such as heating, cooling, and applying mechanical stress. This has applications in studying phase transitions, chemical reactions, and mechanical behavior at the nanoscale (de Jonge & Ross, 2011). Conclusion Electron microscopy is an indispensable tool in modern science and technology, offering unparalleled resolution and versatility for studying structures at the nanoscale. Continuous advancements, such as cryo-EM and in-situ techniques, are expanding its applications and capabilities, driving new discoveries and innovations across various disciplines. Availability of Transmission Electron Microscopy in the Philippines Transmission Electron Microscopy (TEM) is available in the Philippines, primarily in major universities, research institutions, and specialized laboratories. Institutions with TEM Facilities: 1. University of the Philippines (UP): o UP Diliman: The National Institute of Molecular Biology and Biotechnology (BIOTECH) and the College of Science house advanced microscopy facilities, including TEM. o UP Los Baños: The National Institute of Molecular Biology and Biotechnology (BIOTECH) at UPLB also has TEM facilities for research in biology and agriculture. 2. Ateneo de Manila University: o The Department of Biology and the School of Science and Engineering have microscopy facilities, including TEM, for various research applications. 3. De La Salle University: o The College of Science and Engineering provides access to TEM for materials science and nanotechnology research. 4. Industrial Technology Development Institute (ITDI): o Part of the Department of Science and Technology (DOST), ITDI offers advanced analytical services, including TEM, for industrial and scientific research. Costs and Access: Academic Institutions: For students and researchers affiliated with the institution, costs may be subsidized or covered by research grants. External users may need to pay a usage fee, which can range from a few thousand to tens of thousands of pesos per hour. Research Institutions and Commercial Services: Private companies and non-affiliated researchers might incur higher costs, potentially ranging from PHP 5,000 to PHP 20,000 per hour, depending on the facility and services required. Availability of Scanning Electron Microscopy (SEM) in the Philippines Scanning Electron Microscopy (SEM) is available in the Philippines, primarily in universities, research institutions, and specialized laboratories. Institutions with SEM Facilities: 1. University of the Philippines (UP): o UP Diliman: The National Institute of Molecular Biology and Biotechnology (BIOTECH) and the College of Science have SEM facilities.  o UP Los Baños: The National Institute of Molecular Biology and Biotechnology (BIOTECH) at UPLB also provides SEM services. 2. Ateneo de Manila University: o The School of Science and Engineering has SEM facilities for various research applications. 3. De La Salle University: o The College of Science and Engineering offers SEM services for materials science and nanotechnology research. 4. Industrial Technology Development Institute (ITDI): o Part of the Department of Science and Technology (DOST), ITDI offers SEM analysis as part of its advanced analytical services. 5. Other Research Institutions: o Various government and private research institutions also provide SEM services for industrial and scientific research. Costs and Access: The cost of using SEM facilities can vary depending on the institution, the complexity of the analysis, and the duration of use. Here are some general cost considerations: Academic Institutions: Costs for students and researchers affiliated with the institution may be subsidized or covered by research grants. External users may need to pay a usage fee, which can range from PHP 1,000 to PHP 10,000 per hour. Research Institutions and Commercial Services: Private companies and non-affiliated researchers might incur higher costs, potentially ranging from PHP 3,000 to PHP 15,000 per hour, depending on the facility and services required. For specific pricing and availability, it is best to contact the institutions directly or visit their official websites for detailed information.