Electron tomography. fousiya kallayil
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The document discusses electron tomography, which uses electrons instead of other waves like x-rays or radio waves to generate tomographic images. Electron tomography allows for imaging surfaces at the atomic level with resolutions as small as 0.1 nm and magnifications over 100,000x. Scanning tunneling microscopy is also covered, which uses the quantum tunneling phenomenon of electrons to image surfaces at the atomic scale. Key figures from its development like Binnig and Rohrer are credited for inventing the technique and receiving the Nobel Prize for it. Advantages and challenges of both electron tomography and STM are presented.
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This document provides an overview of scanning tunneling microscopy (STM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It describes the basic principles and operation of STM, including how it uses a sharp tip to detect tunneling current at the surface of a sample. It also discusses sample and tip preparation, as well as constant current and height modes. SEM and TEM are briefly introduced, with SEM using secondary electrons to image surface topography and composition, while TEM projects electrons through a sample to image atomic structure.
ETE444-lec3.pdf
This document provides an overview of scanning tunneling microscopy (STM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It describes the basic principles and operation of STM, including how it uses a sharp tip and tunneling current to image surfaces at the atomic scale. It also discusses key aspects of SEM such as how it shoots a beam of electrons at a sample and builds an image from secondary electrons. Finally, it explains that TEM works by sending a beam of electrons through a sample and projecting the transmitted electrons to view internal structure at the nanoscale.
STM ppt
The document provides information about scanning tunneling microscopy (STM). It begins by explaining the quantum mechanical principles behind STM, specifically electron tunneling. It then describes the key components of an STM, including the scanning tip, piezoelectric scanner, distance control system, data processing unit, and vibration isolation system. The document discusses the two main imaging modes of STM - constant height mode and constant current mode. It also outlines how STM works by applying a voltage bias between the tip and sample and measuring the tunneling current. The document concludes by discussing advantages and disadvantages of STM as well as sources of artifacts in STM images.
ETE444-lec3.pptx
This document provides information on several types of microscopy techniques including scanning tunneling microscopy (STM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It discusses the principles, history, operation, and applications of STM for imaging at the nanoscale. SEM is described as using a beam of electrons to examine surface features, morphology, composition and generate images. TEM is explained as sending electrons through a sample to produce a projected image showing atomic arrangement.
TEM.pptx
The scanning tunneling microscope works by using the quantum tunneling effect to image surfaces at the atomic level. It has a sharp metallic tip that is brought very close to a sample surface. A voltage is applied, causing electrons to tunnel through the gap between tip and sample. The tunneling current is measured and used to construct a 3D image of the surface by scanning the tip across in the x and y planes. It has picometer scale resolution and can image individual atoms. The main components are the scanning tip, piezoelectric scanner for precise tip positioning, and electronics to control the distance and measure current. It operates in either constant height or constant current mode.
TEM.pptx
The scanning tunneling microscope works by using the quantum tunneling effect to image surfaces at the atomic level. It has a sharp metallic tip that is brought very close to a sample's surface. A voltage is applied, causing electrons to tunnel between the tip and sample, producing a tunneling current. This current is measured and mapped as the tip scans across the sample, generating a 3D image at the atomic scale with sub-nanometer resolution. The main components are the scanning tip, piezoelectric scanner for precise tip positioning, and a computer for controlling the voltage and recording tunneling current data. It can operate in constant height or constant current mode to produce images related to surface topography or charge density.
Chapter 4 electronic
The document discusses electronics components including cathode ray oscilloscopes, diodes, transistors, and logic gates. It describes how a cathode ray oscilloscope works by using electric fields to deflect electron beams and allows measuring voltage and time periods. Diodes are formed using p-n junctions in semiconductors and allow current to flow in only one direction, enabling rectification. Transistors are three-layer semiconductor devices that can amplify signals and act as switches by using a small current to control a larger current. Logic gates are electronic components that take multiple inputs and provide single outputs to make decisions in electronic systems.
Scanning Electron Microscopy
An electron beam is used to scan the surface of a sample in a SEM. Signals produced from the sample include secondary electrons, backscattered electrons, and X-rays. Secondary electrons provide topographic information and backscattered electrons provide compositional contrast related to atomic number. X-rays allow identification of elements in the sample. The SEM provides higher magnification, greater depth of field, higher resolution, and compositional/crystallographic data compared to an optical microscope, making it useful for research and industry applications.
Electron spectroscopy
This document provides an overview of electron spectroscopy techniques, including X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and ultraviolet photoelectron spectroscopy (UPS). It discusses the basic principles, instrumentation, applications, and advantages/limitations of each technique. XPS is described as using X-rays to eject core electrons and measure their kinetic energy to determine elemental composition. AES uses electrons to eject core electrons which cause additional electrons to fall into the vacancy, emitting energy measured to identify elements. UPS uses UV light to eject valence electrons and measure their kinetic energy to determine molecular orbital energies.
Microwave advancement
1. Microwave diagnostics techniques such as interferometry, reflectometry, scattering and electron cyclotron emission (ECE) have been powerful tools for diagnosing magnetically confined plasmas.
2. Recent advances in electronics and computer technology have enabled the development of advanced microwave diagnostic systems that can measure 2D and 3D profiles of plasma density, temperature, and fluctuations.
3. Key microwave diagnostic techniques discussed in the document are interferometry, reflectometry, and ECE. Interferometry measures line integrated density, reflectometry measures local density, and ECE measures local electron temperature. These techniques provide important information for understanding issues in plasma physics like stability, waves, and transport.
Ion energy Distribution of Multi-Frequency Capacitively Coupled Plasma
This document outlines a study on ion energy distribution (IED) in multi-frequency capacitively coupled plasma. It presents analytical models for IED in triple frequency discharges and examines the effects of various plasma parameters on IED through simulations. The parameters investigated include operating pressure, ion density, RF current density, low frequency, and their effects on the mid-position and width of the IED. The study shows IED can be adjusted by choosing the appropriate fundamental frequency, pressure, and ion density for applications like plasma etching and deposition.
Microprobing with electrons
Electron microprobe analysis (EMPA) is a technique that uses a focused electron beam to determine the elemental composition of materials at the micrometer scale. It works by generating characteristic x-rays from sample atoms when bombarded by electrons. These x-rays can then be analyzed using either wavelength dispersive spectrometry (WDS) or energy dispersive spectrometry (EDS) to identify and quantify elemental composition. EMPA provides highly accurate micrometer-scale compositional data but requires standards for quantification and corrections due to factors like excitation volume.
Scanning tunneling microscope (STM)
This document provides information about a scanning tunneling microscope (STM) including its basic operating principles, design, modes of operation, applications, and related imaging techniques. The STM works by using the quantum tunneling effect to measure electric currents between a sharp tip and conductive sample surface. This allows it to image surfaces at the atomic level with high resolution. The document outlines the key components of an STM including the sample, scanning tip, piezoelectric scanner, and control electronics. It also describes the two main imaging modes of constant current and constant height. Common applications and examples of STM images showing atomic structures are also presented. Finally, related microscopy techniques developed from STM principles are briefly discussed.
Electron microscopy 2
The document provides information about various electron microscopy techniques, including transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and analytical electron microscopy (AEM). It discusses the development of TEM since its invention in the 1930s. It describes various imaging modes in TEM and STEM such as bright field, dark field, high-resolution, and techniques that provide elemental composition like energy-dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS). The document is an introduction to electron microscopy methods.
Search for Neutron Electric Dipole Moment
The document summarizes a proposal for a new neutron electric dipole moment (EDM) experiment at the Spallation Neutron Source (SNS). The experiment aims to improve the current neutron EDM sensitivity by two orders of magnitude using ultra-cold neutrons produced in superfluid helium-4 and polarized helium-3 as a co-magnetometer. Many feasibility studies have been conducted, including tests of the helium-3 spin precession frequency matching technique. Construction of the new neutron EDM experiment is expected to begin in fiscal year 2010 with the goal of reaching a sensitivity of less than 1×10-28 e-cm.
Langmuir probe diagnostics at VINETA II experimental apparatus
VINETA II is an experiment to investigate magnetic reconnection in a controlled laboratory environment. The purpose of this work is to test the Langmuir probe diagnostics system by measuring the time evolution of 2D profiles of highly reproducible transient argon plasma discharges generated by an array of 7 electron guns. This is done by positioning the tip of a Langmuir probe at various positions on a 2D plane and by biasing it with an AC voltage with amplitude in the range 60V-80V and frequency in the range 10 kHz – 100 kHz. The end result is a 2D profile evolving in time for each parameter that can be extracted from the probe (T_e, n_e).
Principle Of A F S
This document discusses various techniques used to characterize surfaces including scanning probe microscopies, electron spectroscopies, vibrational spectroscopies, and ion spectroscopies. It provides details on scanning tunneling microscopy (STM) including the basic principles, instrumentation, imaging modes, applications and examples of STM used to image surface structures and molecular adsorption. Transmission electron microscopy (TEM) is also summarized briefly.
Transmission electron microscope
This document provides an overview of transmission electron microscopy (TEM). It discusses the history and development of TEM, the theoretical background explaining why electron microscopes were needed, an explanation of TEM instrumentation including the electron gun, condenser lens, objective lens and screen. It also covers TEM sample preparation techniques and the types of information that can be obtained from TEM such as thickness, orientation, composition and bonding states. Finally, it notes some limitations of TEM including small sample size, challenges of interpreting 2D images of 3D samples, potential radiation hazards, and the need for very thin electron transparent samples.
Electromagnetically actuated cantilevers
Electromagnetically actuated cantilevers for multi-resonant operation in force/stress sensing application and scanning probe microscopy
Similar to Electron tomography. fousiya kallayil (20)
STM finalfor scanningtunnelingmicroscope experiments.ppt
STM finalfor scanningtunnelingmicroscope experiments.ppt
Ion energy Distribution of Multi-Frequency Capacitively Coupled Plasma
Ion energy Distribution of Multi-Frequency Capacitively Coupled Plasma
Langmuir probe diagnostics at VINETA II experimental apparatus
Langmuir probe diagnostics at VINETA II experimental apparatus
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Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...
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bordetella pertussis.................................ppt
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The debris of the ‘last major merger’ is dynamically young
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Electron tomography. fousiya kallayil
- 3. Imaging by sections or sectioning, through the use of any kind of penetrating wave • Tomograph • Tomogram • Tomographic reconstruction
- 4. Superposition of free tomographic cross sections S1 and S2 compared with the projected image P.
- 5. Physical phenomenon Type of tomogram X-rays CT hyperlinkct.docx Radio-frequency waves MRI hyperlinkmri.docx Muons Muon tomography hyperlinkmt.docx Magnetic particles Magnetic particle imaging hyperlinkmpi.docx Gamma rays SPECT Electron-position annihilation PET hyperlinkpet.docx archaeology Geophysics Oceanography Radiology Biology Materials science Astrophysics Quantum Information and other sciences…
- 7. Wave nature of electrons λ=h/mvλ=h/mv ½ mv½ mv22 =eV=eV λλ=h/=h/√2meV√2meV
- 11. Electron beam hits the sample Producing electron and photon signals Collected by detectors and converted to a voltage and amplified. Applied to grid of CRT Image is formed
- 12. Figures of Merit -higher resolving power~0.1nm -higher magnification~10,00,000X -higher depth of field
- 17. Allows for the imaging of the surfaces of metals and semiconductors at the atomic level. Developed by Gerd Binnig and Heinrich Rohrer at the IBM Zurich Research Laboratory in 1982. The two shared half of the 1986 Nobel Prize in physics for developing STM. Binnig Rohrer
- 18. In classical physics e flows are not possible without a direct connection On an atomic scale a quantum mechanical particle behaves in its wave function. An electron will “jump” from one surface to the other of lower potential. How tunnelling works????? "... I think I can safely say that nobody understands Quantum Mechanics" Richard P. Feynman L
- 19. Basic Principles of STM Electrons tunnel between the tip and sample, a small current I is generated (10 pA to 1 nA). d ~ 6 Å Bias voltage: mV – V range Transmission Probability: T ≈ 16ε(1 – ε)e-2κL
- 20. Two Modes of Scanning Constant Height Mode Constant Current Mode Usually, constant current mode is superior.
- 21. Instrumental Design: Controlling the Tip Raster scanning Precise tip control is achieved with Piezoelectrics Displacement accurate to ± .05 Å
- 22. Raster the tip across the surface The tip-surface separation is controlled to be constant by keeping the tunneling current at a constant value. The voltage necessary to keep the tip at a constant separation is used to produce a computer image of the surface.
- 23. Advantages No damage to the sample Vertical resolution superior to SEM Spectroscopy of individual atoms Relatively Low Cost Disadvantages Samples limited to conductors and semiconductors Limited Biological Applications Generally a difficult technique to perform Figures of Merit Maximum Field of View: 100 μm Maximum Lateral Resolution: 1 Å Maximum Vertical Resolution: .1 Å
- 24. An STM representation of the surface of silicon at the atomic level
- 25. Copper Surface
- 26. Iron on Copper
- 27. Iron on Copper
- 28. Carbon Monoxide Man: CO on Platinum
- 29. Xenon on Nickel
- 30. Wikipedia Google Scanning Tunneling Microscopy.” National Center for Photovoltaic at the National Renewable Energy Laboratory. http://nrel.gov/measurements/tunnel.html “The Nobel Prize in Physics 1986.” Nobel e Museum. http://www. nobel.se/physics/laureates/1986/index.html STM Image Gallery. http://www.almaden.ibm.com/vis/stm/gallery.html