Photoelectric Effect, Energy Levels & LASERs

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Across
  1. 3. the minimum amount of energy needed to eject a (photo)electron from the surface of a metal (4,8)
  2. 5. In Einstein’s photoelectric equation Ekmax is the maximum kinetic energy of an ejected _____________ (8)
  3. 6. number of spectral lines produced by this element? DIAGRAM
  4. 9. photons (or waves) of a single wavelength (13)
  5. 11. a small, cheap, efficient type of laser (13)
  6. 12. the smallest possible amount of light energy (6)
  7. 14. rainbow spectrum with dark lines (10)
  8. 16. the name of the process where a photon of sufficient energy is absorbed by an electron in the ground state, allowing it to be promoted to the topmost energy level in a LASER system
  9. 17. a large, expensive, inefficient type of LASER that utilises mirrors at each end (3)
  10. 18. type of spectrum showing a dark background with coloured lines (8)
  11. 19. a device used to detect the presence of electrical charge (12)
  12. 20. energy necessary to remove an electron from an atom (hint: not φ) (10)
  13. 21. relationship between the incident photon and emitted photon in stimulated emission (8)
Down
  1. 1. the emission of a photon from an excited atom, triggered by an incident photon of energy equal to the energy gap between the excited state and a state of lower energy in the atom (10,8)
  2. 2. In a LASER, how does the length of time spent in the topmost energy level compare to the time spent in the one directly below it? (7)
  3. 4. name for a ‘near stable’ or ‘almost stable’ energy level in a LASER (10)
  4. 6. type of emission from an unstable energy level to one below it
  5. 7. in terms of energy, what is the meaning of hf? (6,6)
  6. 8. (9,9) the minimum frequency for which (photo)electrons are emitted (symbol fo)
  7. 10. when more electrons are in a higher energy state than an (adjacent) lower energy state (10,9)
  8. 13. DIAGRAM (9, 10)
  9. 15. gradient of a kinetic energy vs. frequency graph (6,8)