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M ö ssbauer Effect

M ö ssbauer Effect. 200582116 J-H. Kim 2005. 12. 05. Contents. Motivation - Beginning - Mössbauer Effect(Ir-191) Experiment - Mössbauer Measurements Summary. Summary. Motivation. Applications. What is the M ö ssbauer effect ?. Before the Mössbauer theory . Yes~!.

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M ö ssbauer Effect

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  1. Mössbauer Effect 200582116 J-H. Kim 2005. 12. 05

  2. Contents • Motivation - Beginning - Mössbauer Effect(Ir-191) • Experiment - Mössbauer Measurements • Summary

  3. Summary Motivation Applications What is the Mössbauer effect ? • Before the Mössbauer theory Yes~! I am a nuclei at ground state. I am a nuclei excited state. You will be unstable. Do you want it? I want to go to the excited state. Ok. I will give you a gamma ray for your exciting. Thank you! The energy of my gamma should be smaller than excited since I should be recoiled. This energy is not enough for my exciting.

  4. Summary Motivation Applications What is the Mössbauer effect ? • Before the Mössbauer theory. - The nuclei recoil back with velocity v(βc). - The frequency of gamma ray for absorptionis lower than at the emission. => Then target nuclei cannot absorb the gamma energy. Momentum conservation. Doppler effect. # For Ir-191 (hν = 129 keV) v = 202 m/s E’ = 128.999912874 keV ΔE= 8.71E-5 keV Γ = 3.22E-8 keV (natural line width) ΔE ≫ Γ

  5. Summary Motivation Applications What is the Mössbauer effect ? • Beginning - Rudolf Mössbauer.(1929~?, German physicist) - Discovered the recoil-free emission and absorption of gamma rays by nuclei. (in 1958) - Win the Novel prize. (in 1962) • Experiment ( Recoil Free Nuclear Radiation ) - Ir-191 • How atom can recoil-free emission and absorption? - Atoms are held tightly in crystalline atomic structures

  6. Summary Motivation Applications What is the Mössbauer effect ? • Beginning with the Mössbauer theory I am a nuclei at ground state. I am a nuclei excited state. I can give you an energy for your exciting. Really? but.. I don’t believe you. -_-;; I am K-U.Choi nuclei. I have a different flavor than yours. K-U.Choi stick me on this space with silicon! so I can have little momentum. Really? I believe you then.

  7. Summary Motivation Applications What is the Mössbauer effect ? • Beginning with the Mössbauer theory. - We don’t know the share the required momentum. - I calculate the number of nuclei for the condition. ΔE<Γ (ΔE=E_pt-E_pt’) # For Ir-191 (hν = 129 keV) N=2700, v = 7.5 cm/s, E’ = 128.99999999… keV - N ≪ 1 mol(10E23) =>velocity and energy loss is very small. # For Ir-191 (hν = 129 keV), N = 1mol v = 2E-19 cm/s≒ 0 cm/s

  8. Intensity 0 ΔE 0 Velocity Summary Motivation Applications How to measure the Mössbauer effect. • Measurement for Mössbauer effect. Data Equipment Source. Detector. Absorber.

  9. Summary Motivation Applications Applications. • What can we measure with Mössbauer effect? 1. The lifetime determinant for an excited particle. 2. Nuclei energy level. 3. The general relativity theory. - Gravitational red shift. 4. The hyperfine structure. - The nuclear isomer shift. - The nuclear Zeeman effect. - The nuclear quadrupole splitting.

  10. Summary Motivation Applications 1. The lifetime determinant for an excited particle. • Particle lifetime of an excited state in a nucleus. - τ=Δt : particle lifetime. - ΔE(Γ/2) : can be determined in Mössbauer experiment. The Breit-Wigner distribution : Γ : natural line width. x axis : energy y axis : absorption cross section.

  11. Summary Motivation Applications 2. The general relativity theory. • Gravitational red shift. - E_0 = hν = 14.4 keV - Gravitational red shift. ν=ν_0(1+(gh/c^2)) ΔE=2*ν_0(gh/c^2) ΔE

  12. Summary Motivation Applications 3. The hyperfine structure. • The nuclear isomer shift. • The nuclear Zeeman effect. • The nuclear quadrupole splitting.

  13. Summary Motivation Applications 3. The hyperfine structure.

  14. Summary Motivation Applications Summary • What is the Mössbauer effect? For nuclei in crystalline atomic structures, the gamma radiation emitted from the nuclei are approximately recoil-free. • How to measure the Mössbauer effect. 1. Gamma-ray source, an absorber, Gamma Detector. 2. Relative velocity of varying the gamma-ray energy. • Applications 1. The lifetime determinant for an excited particle. 2. The general relativity theory. 3. The hyperfine structure.

  15. Thank you.

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