Introduction to Electron Microscopy Prof. David Muller‚ dm24@cornell.edu Rm 274 Clark Hall‚ 255-4065 Ernst Ruska and Max Knoll built the first electron microscope in 1931 (Nobel Prize to Ruska in 1986) T4 Bacteriophage Electron Microscopy bridges the 1 nm – 1 μm gap David Muller 2008 between x-ray diffraction and optical microscopy Tools of the Trade AFM MFM Scanned Probe Microscope (includes Atomic Force Microscope) Transmission Electron Microscope Scanning Electron Microscope
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Building materials of a cell are composed of two atoms that form molecules. A chemical bond is created when two atoms share an electron. Also called covalent bond because they share valence electrons. A covalent bond‚ which is the strongest bond‚ takes action when two atoms valence overlap. For example‚ there are two suns and the light that shines from the two solid spheres forms many rays making a radiant cloud around each of the two. If these suns move closer together the radiant shine would
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JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS‚ VOLUME 1‚ NUMBER 3‚ SUMMER 2000 Comparison between TG-51 and TG-21: Calibration of photon and electron beams in water using cylindrical chambers S. H. Cho‚a) J. R. Lowenstein‚b) P. A. Balter‚c) N. H. Wells‚d) and W. F. Hansone) Department of Radiation Physics‚ The University of Texas M.D. Anderson Cancer Center‚ 1515 Holcombe Boulevard‚ Box 547‚ Houston‚ Texas 77030 ͑Received 31 March 2000; accepted for publication 8 June 2000͒ A new calibration
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Laboratory I: Problems 4 and 5 Deflection of an Electron Beam by an Electric Field and Deflection of an Electron Beam and Velocity By: John Greavu Partners: Shane Ruff‚ Hannah Eshenaur‚ & David Sturg Professor: John Capriotti TA: Barun Dhar July 19‚ 2013 OBJECTIVE: The objective of this lab was to scientifically determine the deflection of an electron from its original path due to its passing through an electric field as a function of the electric field strength (problem 4)‚ as well as its initial
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The electron charge to mass ratio is a widely known in the scientific field as a value that measures the charge of a standard electron versus its mass. Once the electron is accelerated by a voltage difference the potential energy is then converted to kinetic energy. When an electron is placed into a magnetic field it experiences a force that is perpendicular to the velocity of the electron and the magnetic field. This causes the electron to move in the pattern of a circle‚ and centripetal force is
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the atom and of covalent and ionic bonding that students have used so far emphasizes the attractions between bonding atoms. The nucleus‚ electrons‚ and double-headed arrows show that the protons and electrons from one atom attract the oppositely charged electrons and protons of the other atom‚ resulting in bonding. The energy levels show that only valence electrons are involved in bonding. After students understand the important role of attraction of opposite charges‚ you may introduce them to a common
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October 30‚ 2014 Jordan Hollenbeck Juhn Borruel Electron Gun - Effects of a Magnetic Field Purpose: The objective of this experiment is to study the motion of an electron in a magnetic field and to establish (show/verify) a relationship between the magnetic strength and the distance the electrons are deflected. Theory and Procedure: The electron gun is an instrument that consists of an electron source (which emits electrons and focus the stream into a beam)‚ a magnetic coil (which uses a voltage
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Deflection of an Electron Beam by an Electric Field Nicole N Lab Problem 1.4 – February 3‚ 2011 Problem Statement: We were asked to test the design of an electron microscope to determine how a change in the electric field affects the position of the beam spot. The goal is to find out how different variables‚ such as charge of the deflection plates providing a vertical electric field and initial velocity of the electron beam will affect the amount of deflection the electron beam experiences
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SOFTWARE CONFIGURATION MANAGEMENT Introduction Lehman’s Law of Software Evolution predicts that change in software is inevitable and it is not a consequence of bad programming. There are also limit to what can be achieved by a software evolution team in safely implementing changes and new functionality. Software evolution reacts to the need of changes on the software system for various reason including bug fixes‚ declining performance‚ increasing complexity and adapting to new platform. Software
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Software Configuration Management Section A: Multiple Choices 1) Which of the following should be considered as Configuration Items for any project: Project plan‚ Requirement specification‚ Class diagrams Design specification‚ Design tools‚ Activity diagrams Source Code‚ Test plan‚ test Script‚ Test tools‚ Test results All of the above 2) In check-in‚ check-out model‚ version branching and merging are represented by a structure known as Version Graph History Graph Structure
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