* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Diapositive 1 - SLC Home Page
Probability amplitude wikipedia , lookup
Renormalization wikipedia , lookup
History of quantum field theory wikipedia , lookup
Matrix mechanics wikipedia , lookup
Ensemble interpretation wikipedia , lookup
Bremsstrahlung wikipedia , lookup
Relational approach to quantum physics wikipedia , lookup
Photon polarization wikipedia , lookup
Elementary particle wikipedia , lookup
Wave packet wikipedia , lookup
Standard Model wikipedia , lookup
Nuclear structure wikipedia , lookup
Future Circular Collider wikipedia , lookup
Dirac equation wikipedia , lookup
Relativistic quantum mechanics wikipedia , lookup
Arthur Compton wikipedia , lookup
Quantum electrodynamics wikipedia , lookup
Atomic nucleus wikipedia , lookup
Quantum tunnelling wikipedia , lookup
Uncertainty principle wikipedia , lookup
Old quantum theory wikipedia , lookup
Double-slit experiment wikipedia , lookup
Photoelectric effect wikipedia , lookup
Bohr–Einstein debates wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
3/21/2013 Quantum Physics versus Classical Physics The Thirty-Year War (1900-1930) Models of the Atom • Democritus, Dalton and Mendeleïev Interactions between Matter and Radiation • 1897 Thomson’s Plum Pudding Model and the Discovery of the Electron • Models of the Atom • 1911 Rutherford’s Model and the Discovery of the Nucleus • Bohr’s Model of the Atom • 1913 Bohr’s Planetary Model and Spectral Lines • Planck’s Blackbody Radiation • 1926 Schrödinger’s Cloud Model and the Probability Wave Function • Einstein’s Photoelectric Effect • Compton’s Effect • De Broglie’s Matter Waves • Quantum Mechanics Democritus, Dalton, and Mendeleev 1897 Thomson’s Plum Pudding Model and the Discovery of the Electron Dalton’s compounds Mendeleev's periodic table of elements Experimental Set-Up Plum Pudding Model 1 3/21/2013 1911 Rutherford’s Model and the Discovery of the Nucleus Bohr’s Model of the Atom • Classical Model of the Atom • Atomic Spectra • 1913 Bohr’s Planetary Model • Bohr’s Atom • Atomic Spectra Explained • Bohr’s Correspondence Principle • Energy-Level Diagrams Classical Model of Atom Atomic Spectra Why do atoms of a given element exhibit only certain spectral lines? Why do atoms absorb only the frequencies (wavelengths) that they were emitting? Hydrogen Spectral Lines The Balmer Spectrum of Hydrogen 2 3/21/2013 1913 Bohr’s Planetary Model • What is the arrangement of the electrons around the nucleus? • What keeps the electron from falling into a positive nucleus by electrical attraction? • Why do elements exhibit different atomic spectra of discrete lines? Atomic Spectra Explained 1900 Planck’s Blackbody Radiation • Thermal Radiation • Blackbody • Blackbody Radiation • The UV Catastrophe • Planck’s Quantum of Energy • Blackbody Explained by Bohr’s Atom Bohr’s Atom Energy-Level Diagrams Thermal Radiation 3 3/21/2013 Blackbodies Blackbody Radiation • Stars’ Surface Temperatures Power (area under curve) increases with T Stefan-Boltzmann’s Law P = A e T4 • Peak wavelength decreases as T increases Wien’s Law max T = 0.002898 m K The energy output and peak wavelength of the blackbody radiation curve both give the surface temperature of stars. 4 3/21/2013 The UV Catastrophe Formative Quiz The temperature of your skin is approximately 35 0C. (a) What is the peak wavelength of the radiation it emits? (b) What is the total power emitted by your skin. Assume that the area of your skin is 2.0 m2. (c) Why don’t you glow as bright as a light bulb? Blackbody Explained by Bohr’s Atom Our Universe is a Blackbody (Cosmology and Quantum Physics) 1905 Einstein’s Photoelectric Effect Albert Einstein Nobel Prize 1921 • Experiment • Classical Physics • Experimental Results • Einstein’s Interpretation • Applications 5 3/21/2013 Experiment Einstein’s Interpretation Kmax = h f - Kmax maximum kinetic energy of elected electrons (photoelectrons) h Planck’s constant f frequency of light work function of the metal Applications Classical Physics vs Experimental Results Formative Quiz The maximum electron energy in a photoelectric experiment is 3.4 eV. When the wavelength of the illuminating radiation is increased by 25%, the maximum electron energy drops to 2.6 eV. (a) What is the original wavelength of the illuminating radiation? (b) What is the work function of the emitting surface? Medicine Automatic Door Openers 6 3/21/2013 Film Photomultiplier Tube Automatic Camera Solar Panels Smoke Detector 7 3/21/2013 Experiment 1923 Compton’s Effect Arthur Compton Nobel Prize 1927 • Experiment • Classical Physics • Experimental Results • Compton’s Interpretation • Applications Classical Physics vs Experimental Results Compton’s Interpretation Photons have momentum p = h / Compton Shift = ’ - 0 = (h / (me c)) (1 – cos ) Compton’s Wavelength of Electron C = h / (me c) = 0.00243 nm Peak at 0 Photons interact with electrons tightly bound to the atom (effectively they collide with the atom itself) leading to a Compton shift too small to be detected. Formative Quiz X-rays of wavelength = 22 pm are scattered from a carbon target and the scattered x-rays are detected at 850 to the incident beam. Application Dental X - Rays (a) What is the Compton shift of the scattered x-rays? (b) What percentage of the initial x-ray energy is transferred to an electron in such scattering? 8 3/21/2013 Photons and Electromagnetic Waves 1923 De Broglie’s Matter Waves Louis De Broglie Nobel Prize 1929 Shortest doctoral thesis on record • Matter Waves • Davisson-Germer Experiment • Electron Diffraction and Interference Patterns • Application: The Electron Microscope Matter Waves 1927 Davisson-Germer Experiment De Broglie’s wavelength = h / p = h / (m v) frequency of a particle f = E/h Equations contain both particle (p and E) and wave ( and f) quantities. First experimental evidence of the wave nature of particles (electrons). Electron Diffraction Pattern The Electron Microscope 9 3/21/2013 Quantum Mechanics • 1925 Heisenberg’s Uncertainty Principle • Barrier Tunnelling • Applications Head of an Antarctic Mite magnified 1500 times • 1926 Schrödinger’s Cloud Model • Probability Density and Electron’s Orbitals • Schrödinger's Cat • 1928 Dirac’s Equation 3-D nanostructure: “flowers" of silicon carbide and gallium Hydrothermal Worm 1925 Heisenberg’s Uncertainty Principle Barrier Tunnelling x px h / 4 E t h / 4 Applications Scanning Tunnelling Microscope • Alpha Decay • Nuclear Fusion • Scanning Tunnelling Microscope 10 3/21/2013 1926 Schrödinger’s Cloud Model Schrödinger’s Cat Probability Density and Electron’s Orbitals 1928 Dirac’s Equation • Dirac’s equation describes the evolution of the wave function of a relativistic particle. It includes quantization of energy. • Dirac predicted the existence of antimatter (positron). The positron was first observed in 1933. First positron track observed in a cloud chamber. Summary • • • • • • • • • • • 1897 Thomson Discovery of the Electron 1900 Planck Blackbody Radiation 1905 Einstein Photoelectric Effect 1911 Rutherford Discovery of Nucleus 1913 Bohr Quantum Model ofAtom 1923 Compton Effect 1923 De Broglie Matter Waves 1925 Heisenberg Uncertainty Principle 1926 Shrödinger Wave Function 1927 Davisson-Germer Experiment 1928 Dirac Equation 11