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Resonant photon absorption

Resonant photon absorption. The Mossbauer effect. Source. Detector.  x. Absorber. Atomic interactions. Photon attenuation. Radiation attenuation by: -- photoelectric effect -- compton scattering (E  << 1.02 MeV). Source. Detector.  x. Absorber. E *. E *. 0.0. 0.0.

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Resonant photon absorption

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  1. Resonant photon absorption The Mossbauer effect

  2. Source Detector x Absorber Atomic interactions Photon attenuation Radiation attenuation by:-- photoelectric effect-- compton scattering (E << 1.02 MeV)

  3. Source Detector x Absorber E* E* 0.0 0.0 Photon attenuation Consider nuclear resonant absorption Assumesourceandabsorberare identical

  4. emission absorption Source Detector x Absorber  for resonant absorption E* E* 0.0 0.0 Kinematics Assumesourceandabsorberare identical

  5. Ignore energy scale Source Absorber

  6. E* E* 0.0 0.0 Natural width of the state Estimates Consider an 57Fe source 57Co 57Co Fe

  7. Enter -- Mr. Mossbauer Place 57Fe source bound in a metal matrix Resonant Absorption! Place 57Fe absorber bound in a metal matrix

  8. +v -v Source Detector x Absorber E* E* 0.0 0.0 move source Kinematics Doppler shift frequency:h’- h = ED move source Assumesourceandabsorberare identical

  9. -v no resonant absorption Source Absorber

  10. -v no resonant absorption Source Absorber

  11. -v small resonant absorption Source Absorber

  12. -v more resonant absorption Source Absorber

  13. v = 0.0 maximum resonant absorption Source Absorber

  14. -v less resonant absorption Source Absorber

  15. -v small resonant absorption Source Absorber

  16. -v no resonant absorption Source Absorber

  17. -v no resonant absorption Source Absorber

  18. Resulting transmission curve

  19. Source Detector x Absorber Es* Ea* 0.0 0.0 Kinematics Assume source and absorber are NOT identical

  20. move absorber! +v -v Source Detector x Absorber Es* Ea* when - 0.0 0.0 Doppler kinematics Assume source and absorber are NOT identical Resonant absorption

  21. -v Absorber transition energy shifted no resonant absorption Source

  22. -v Absorber transition energy shifted small resonant absorption Source

  23. -v Absorber transition energy shifted more resonant absorption Source

  24. -v Absorber transition energy shifted more resonant absorption Source

  25. Absorber transition energy shifted v = 0.0 less resonant absorption Source

  26. -v Absorber transition energy shifted smallresonant absorption Source

  27. -v Absorber transition energy shifted no resonant absorption Source

  28. -v Absorber transition energy shifted no resonant absorption Source

  29. -v Absorber transition energy shifted no resonant absorption Source

  30. “Isotope shift” Doppler energy shifted

  31. move absorber! +v -v Source Detector x Absorber Es* Ea* 0.0 0.0 when - Isotope shift Isotope shift:Level shifts due to atomic electronic charge distribution in the nucleus. Resonant absorption Constant velocity data

  32. 57Fe What is the J for the ground state and the 14.4 Kev state? ENSDF/NNDS What is the multipolarity of the transition? What is the degeneracy for the-- ground state and the -- 14.4 Kev state? If there is a B field, then we can have a nuclear Zeeman effectthat will remove the degeneracies

  33. move source with constant acceleration -v +v Source Detector x Absorber m-sublevels Es* 0.0 57Fe

  34. Dipole transition selection rules

  35. = dwell time v = one channel 0 -v +v Source velocity curve t v = 0 maximum +v v = 0 time maximum -v v = 0 Source displacement curve Mossbauer resonant absorption with constant acceleration Use MCS/MCA data

  36. Source Detector x Absorber m-sublevels Es* 0.0 Possible absorption transitions

  37. m-sublevels Possible absorption transitions 6 4 2 5 3 1

  38. Possible absorption transitions Compare these predictions with the measurements… …follow guidelines in Problem. 10.C. and eventually determine

  39. The Pound-Rebecca Experiment Be prepared to explainwhat the experiment discoveredandhow the Mossbauer resonant photon absorption was essential to the measurement.

  40. m-sublevels Possible absorption transitions Case1 6 4 2 5 3 1

  41. m-sublevels Possible absorption transitions Case2 5 3 1 6 4 2

  42. 6 5 3 4 2 1 Possible absorption transitions m-sublevels Case3

  43. 6 5 4 3 2 1 Possible absorption transitions m-sublevels Case4

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