--  Review - four basic quantum numbers: n, I, m_l, m_s.   Zeeman effect (splitting of lines by an ext. mag. field) 
--  spectroscopic notation, e.g. sodium (Na) in the ground state:  1s² 2s² 2p⁷ 3s
--  computer program - Micasoft, M1, "Atoms"
--  x-ray production - bremsstrahlung, characteristic radiation - demo
--  x-ray machine in room 114: photo 1, 2, 3, 4.  Diagram (PH 352 writeup).  SEM - nut, x-ray graph
--  fluorescence and phosphorescence - demo: fluorescent tube, darkroom timer dial
--  laser: light amplification by stimulated emission of radiation.
--  properties of light: 1. very directional, 2. monochromatic, 3. coherent (waves are in step)
--  demo - HeNe laser without the cover, tuning forks (440 Hz, 512 Hz)
--  distinguish:  photon absorption, spontaneous emission, stimulated emission
--  Needed for a laser: 1. cavity, 2. medium, 3. pump
--  description of a HeNe laser...  population inversion...  l = 632.8 nm, E = hf = hc/l = 1.96 eV
--  laser applications: 1. scanner (e.g. CD), 2. straight lines, 3. safety reflectors, 4. distance measurements, 5. light pipe (fiber optics), 6. absorption by dark material, 7. cutting, 8. guidance of weapons, 9. light shows, 10. laser printers, 11. holography.
--  Video 17 - "Carbon Dioxide Laser", Optics I, #8, 4:05

--  holography: 3D images recorded on photographic film.  Video 18 - "Holography", Optics II, #8, 3:18 
Chapter 30.  Nuclear Physics and Radioactive Decay
-- history:  1895 - William Roentgen discovered x-rays, 1896 - Henri Becquerel discovered radioactivity (of uranium), 1897 - Marie and Pierre Curie isolate radium and polonium (both radioactive), 1898 - Ernest Rutherford began studying the various rays that were emitted: alpha, beta and gamma
-- behavior in a magnetic field ...
-- From later experiments:  alpha are doubly ionized helium atoms (He⁺⁺), beta are electrons, gamma are electromagnetic waves (photons) with a very short wavelength.
  Z = atomic number = no. of protons in the nucleus
  A = mass number = no. of protons and neutrons in the nucleus
  N = A - Z = no. of neutrons in the nucleus
--  definitions of nuclides (same Z, A and N), isotopes (same Z), isotones (same N), isobars (same A)
--  general nuclide designation ...
--  nuclear radius = r = 1.2 fm A^1/3, nuclear volume = V = 7.2 x 10^-45 m³ A, nuclear density = 2.4 x 10¹⁷ kg/m³
--  unified atomic mass unit = 1 u = 1.6605 x 10^-27 kg = 931.5 MeV
--  show how to calculate the binding energy of ⁷Li