Create Presentation
Download Presentation

Matter and Radiation - Francis-12 Suggested reading: The Particle Adventure at: http://particleadventure.org/index.h

Matter and Radiation - Francis-12 Suggested reading: The Particle Adventure at: http://particleadventure.org/index.h

52 Views

Download Presentation
Download Presentation
## Matter and Radiation - Francis-12 Suggested reading: The Particle Adventure at: http://particleadventure.org/index.h

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Matter and Radiation- Francis-12**Suggested reading: The Particle Adventure at: http://particleadventure.org/index.html**Matter and Radiation**localized point sources of mass waves in a continuous potential field We interrogate matter with radiation Suggested reading: The Particle Adventure at: http://particleadventure.org/index.html**Fermionic Matter :**• In the paradigm of particle physics, the material world is made up of 4 “fundamental or elementary” particles called Fermionsthat have quatum spin numbers that are odd multiples of ½, and thus obey the Pauli exclusion principle (only one particle can occupy any given quantum energy state simultaneously) and that feel the force of gravity, that is to say that they have mass. Proton = 2 Up Quarks per Down Quark Neutron = 2 Down Quarks per Up Quark**Hadrons are composed of Quarks, which feel the 3 fundamental**forces: electromagnetic, weak, and strong Protons comprised of: 2 Up Quarks / 1 Down Quark Neutrons comprised of: 1 Up Quarks / 2 Down Quark; not stable in isolation**Leptons lack the colour charge which feels the strong force.**The electron is stable, but neutrino types oscillate between each other**Protons and neutrons must be colour neutral in terms of the**sum of the strong charges of their constituent quarks: red + green + blue = white. Note: the actual number of quarks in protons and neutrons is unknown, but the ratio of Up to Down quarks is fixed. Cartoon of Helium Atom**Radiation:**Unlike matter, which is conceptualized as being comprised of localized “point source” particles, radiation has classically been thought of as continuous waves in an infinite field. Electromagnetic Radiation: Continuous waves in an electromagnetic field. f = / f = frequency (cycles/sec) v = velocity (distance/sec) = wavelength (distance) The frequency of a light wave is constant, but its velocity, and thus wavelength, are functions of the media through which it is traveling. In Quantum Theory, electromagnetic radiation is composed of discrete particles of energy called photons, which interact with protons and electrons, and carry discrete amounts of energy given by their frequency: E = h × f h = Planck's constant (1.38 × 10-16 erg sec). Visible light is a small portion of the electromagnetic radiation spectrum, with wavelengths 400m(blue) and 700 m(red).**Gauge Bosons:**• Photons are members of a larger class of particles called gauge bosons, which are characterized by quantum spin numbers that are integers, and thus do not obey Pauli’s exclusion principle; that is they are able to flock together at the same energy level. Bosons are the messengers that carry or mediate the 4 fundamental forces: • Photons carry the electromagnetic force, represents the quanta of the electromagnetic field. • W+, W-, and Zo Bosons carry the weak nuclear force that controls the interaction between protons and neutrons by changing the flavors of quarks. They represent the quanta of the weak nuclear force. The W+ and W- decay rapidly to electrons or positrons plus neutrinos • 8 species of Gluons carry the strong nuclear force that keeps the quarks together in protons and neutrons. They do not feel the electromagnetic force. The residual strong force keeps protons and neutrons together in the nucleus. • Gravitons might carry the force of gravity, they are the quanta of waves in a gravitational field • Higgs particle may carry mass, a quanta of disturbance in the Higgs field, which gives mass to hadrons, Z and W bosons, electrons**Principles of conservation**In the same way that we assume there is a conservation of mass, energy, and electromagnetic charge, there are also the following additional conservations laws: Conservation of Baryon Number Particle - particle interactions can not change the number of net baryons e+ + n p+ + ve p+ n + e+ + ve Conservation Lepton Number Particle - particle interactions can not change the number of net leptons ve+ n p+ + e-**There are 2 successive families of heavier unstable**fundamental particles. In string theory, these successive families of fundamental particles would correspond to increasing harmonics in the vibrational frequencies of strings, branes, etc. that determine mass. Unstable These heavier particles have very short half-lives and decay rapidly to the more familiar stable Family 1 particles. Stable Particles constituents of Protons and Neutrons**Fundamental Equivalencies:**• Energy of Photons • E = h×ergs per single photon • E = h×c / ergs per single photon • h = Planck's constant = 1.38 10-16 erg sec • Etotal = ×T4 = ergs/sec/m2 of all photons • =Stefan-Boltzman Constant • Energy Equivalent of Mass: • Eannihilation = M ×c2 ergs gm cm2/sec2 • c = speed of light = 2.997 1010 cm/sec**Kinetic Energy:**• Ekinetic = 1/2 × n × Mm × V2 3/2 ×n ××T = 3/2 ××P ×V / R = Boltzmann factor = 1.38 10-16 erg/K • * Only strictly true for relatively low temperature (T < 500 K). Between 500 and 3000 K • rotation energy becomes important, and above 3000 K, bond vibrational energy • becomes a significant factor. • Gravitational Energy: • Egravitational pot. = - G × M / R gravitational potential energy per unit mass • at the surface of a sphere of uniform mass • of radius R • Ecollapse = - G × M2 / (1/R2 - 1/ R1) = ∆Egp M • gravitational energy release for the collapse • of uniform cloud of mass M from a radius • of R1 to a radius of R2. • G = gravitational constant = 6.673 10-8 cm3 / sec2**Electromagnetic Radiation**• Black Body Radiation: • All matter emits continuous • background electromagnetic • radiation whose energy • is a function of temperature. • Total emitted radiant energy: • Etotal = ×T4 = ergs/sec/m2 • = Stefan-Boltzmann constant = 5.672 10-16 erg/K • Eλ = 2hc2/λ5×1/(e(hc/λ(T-1)) • Energy of most abundant photon: • E = hm = hc/m 3 ××T • = Boltzmann factor = 1.38 10-16 erg/K • T = hc/3m • T = (2897.8 / m) K = Wien’s Law, where m is the wavelength of the most abundant photons**Emission Spectra:**In addition to continuous background radiation, relatively diffuse matter, such as a heated gas or spark source, emits radiation with specific energies related to the energy differences between the orbital levels of the atoms making up the source. When a given atom is excited, energy is absorbed by electrons being promoted to higher energy orbitals. When a promoted electron falls back to a lower energy orbital, it gives off a photon whose wavelength corresponds to the energy difference between the orbitals. The electronic orbital structure of any given atom leads to a characteristic set of spectral emission lines whose energies correspond to the energy differences between the atoms orbitals. The energies (and thus wavelengths) of set of spectral emission lines constitute a fingerprint of the electronic structure of the atom, which forms the basis of most modern analytical techniques.**Chemical Analysis**Characteristic Spectral Lines**~ 1 micron**spot Elemental Emission lines from Excited Matter Electron Microbe Analysis of a Hornblende Crystal**Absorption Spectra:**When radiation passes through relatively cool (compared to the effective temperature of the radiation) gas, a characteristic set of dark absorption lines is produced in the electromagnetic spectrum, whose wavelengths (and thus energies) correspond to the emission lines of the same material. The atoms of the gas selectively absorb photons whose energies correspond to the energy differences between their orbitals by promoting electrons from lower to higher energy orbitals. The intensity and distribution of these absorption lines are used to determine the chemical composition of stars, as well as the relative velocities of stars with respect to ourselves. Characteristic Spectral Lines**Electromagnetic Radiation and the State of Matter:**• The state of matter is a function of temperature and the energy of the dominant photons of electromagnetic radiation at that temperature: • Plasma or fully ionized Gas: O & B spectral class stars • M2+ M(Z) + (Z-2)e-T 25,000+K, Eion 10 eV • Ionic Gas: A & F spectral class stars • Mo M2+ + 2e- • Atomic Gas:G & K spectral class stars • M2 2MoT 6000+K, Edissoc 60 kcal/mole • MO2 Mo + O2 • Oxide Condensate:Rocky Planets • MO, MO2, M2O3T 1000 - 1500K, Evap10 kcal/mole • Hydroxide Condensate: • MO2 + H2O M(OH)2T 500K, Ehydration 5kcal/mole