Electron ballistics
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This document discusses electron ballistics and its applications. Electron ballistics is a branch of electronics that deals with the motion of free electrons in electric or magnetic fields. Some applications of electron ballistics include ballistic electron emission spectroscopy (BEEM), which uses a scanning tunneling microscope technique to study ballistic electron transport through materials and interfaces with nanometer resolution. Another application is ballistic electron surface-emitting devices that use carbon nanotubes as electron emitters for field emission displays.
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This document discusses the physics of atoms and their subatomic particles. It describes the Bohr model of the atom, which depicts electrons orbiting the nucleus in fixed orbits or shells. When electrons move between these shells, energy is absorbed or emitted in the form of radiation. The document also outlines the discoveries of subatomic particles like electrons, protons, and neutrons through experiments such as Rutherford's gold foil experiment and Chadwick's work. Finally, it provides the names, symbols, masses, and charges of the basic particles that make up an atom: protons, neutrons, and electrons.
Atomic structure & chemical bond
1) The presentation summarizes atomic structure and chemical bonding models including fundamental particles, Rutherford and Bohr atomic models, quantum numbers, and types of chemical bonds.
2) It discusses limitations of earlier atomic models and introduces concepts like electron energy levels, photon energy, and spectral lines.
3) Various types of chemical bonds are defined including ionic, covalent, and metallic bonds. Molecular orbital theory of covalent bonding is also introduced.
Structure of atoms .pdf
1. Dalton's atomic theory proposed that matter consists of indivisible atoms and that atoms of different elements differ in mass. Compounds are formed by atoms combining in fixed ratios.
2. Rutherford's gold foil experiment showed that the positive charge and mass of an atom are concentrated in a very small nucleus, with electrons orbiting the nucleus.
3. The discovery of subatomic particles like electrons, protons, and neutrons led to modifications of atomic structure, with atoms composed of a nucleus surrounded by electrons.
Structure of atom
Introduction
Discovery of Sub-atomic Particles
Atomic Models
Developments leading to Bohr’s Model of atom
Bohr’s Model for Hydrogen atom
Quantum Mechanical Model of the atoms
Quantum numbers chemisrty
1) The document discusses the topic-structure of an atom and summarizes the key discoveries that led to modern atomic theory, including the discovery of the electron, proton, neutron, and development of atomic models.
2) It describes Michael Faraday's experiments in the 1830s that provided early insights into atomic structure and the discovery of the electron in the 1850s from cathode ray experiments.
3) The document also summarizes Bohr's 1913 model of the hydrogen atom which explained its spectral lines by postulating stable electron orbits, and the development of quantum mechanics and Schrodinger's equation to more fully describe atomic structure.
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- 2. 1. The electron is subatomic particle. 2. It belongs to lepton particle family. 3. Negatively charged particle. 4. They revolve around nucleus. 5. Posses both wave and particle nature. ELETRON-
- 3. BALLISTICS- • Ballistics is the science of mechanics that deals with the launching, flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance. • BALLISTIC BODY- A ballistic body is a body with momentum which is free to move, subject to forces, such as the pressure of gases in a gun or a propulsive nozzle, by rifling in a barrel, by gravity, or by air drags.
- 4. HISTORY OF BALLISTICS- 1. Stones, spears and sticks. 2. Archery. 3. Catapult. 4. Guns, rifles. 5. Present…
- 5. PRESENT TECHNOLOGY- • HIGH CALIBER PISTOLS. • SNIPERS. • RIFLES. • ICBM: INTER CONTINENTAL BALLISTIC MISSILE. AGNI-III
- 6. ELECTRON BALLISTICS- • Electron ballistics is a branch of electronics that deals with the motions of free electrons or other electric particles in electric or magnetic fields.
- 7. APPLICATIONS- 1. BEEM – Ballistic Electron Emission Spectroscopy. 2. Ballistic electron surface-emitting device. 3. Sub-100-nm negative bend resistance ballistic sensors for high spatial resolution magnetic field detection.
- 8. BALLISTIC ELECTRON EMISSION SPECTROSCOPY: • BEEM is a technique for studying ballistic electron transport through a variety of materials and material interfaces. BEEM is a three terminal scanning tunneling microscopy (STM) technique. The most popular interfaces to study are metal-semiconductor Schottky diodedes.
- 9. BEEM-WORKING: 1. Eelectrons are injected from a STM tip into a grounded metal base of a Schottky diode. 2. A small fraction of these electrons will travel ballistically through the metal to the metal-semiconductor interface where they will encounter a Schottky barrier. 3. Those electrons with sufficient energy to surmount the Schottky barrier will be detected as the BEEM current. 4. The atomic scale positioning capability of the STM tip gives BEEM nanometer spatial resolution. 5. In addition, the narrow energy distribution of electrons tunneling from the STM tip gives BEEM a high energetic resolution (about 0.02 eV).
- 10. BALLISTIC ELECTRON SURFACE- EMITTING DEVICE: • A ballistic electron surface-emitting device (BSD) emitter that can be used in a field emission display (FED). The emitter being made of metallic carbon nanotubes extending in a direction that is normal to a surface of the cathode. The carbon nanotubes are designed so that electrons therein can experience a ballistic effect where the mean free path between collisions is as large or larger than a length of the carbon nanotube and that the width of the carbon nanotube being a fermi wavelength. On an opposite end of the carbon nanotubes is a thin metal electrode layer and a thin insulating layer to protect the carbon nanotubes from damage. • ZUSAMMENFASSUNG(COMBINATION).