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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 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 Photon attenuation Consider nuclear resonant absorption Assumesourceandabsorberare identical
emission absorption Source Detector x Absorber for resonant absorption E* E* 0.0 0.0 Kinematics Assumesourceandabsorberare identical
Ignore energy scale Source Absorber
E* E* 0.0 0.0 Natural width of the state Estimates Consider an 57Fe source 57Co 57Co Fe
Enter -- Mr. Mossbauer Place 57Fe source bound in a metal matrix Resonant Absorption! Place 57Fe absorber bound in a metal matrix
+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
-v no resonant absorption Source Absorber
-v no resonant absorption Source Absorber
-v small resonant absorption Source Absorber
-v more resonant absorption Source Absorber
v = 0.0 maximum resonant absorption Source Absorber
-v less resonant absorption Source Absorber
-v small resonant absorption Source Absorber
-v no resonant absorption Source Absorber
-v no resonant absorption Source Absorber
Source Detector x Absorber Es* Ea* 0.0 0.0 Kinematics Assume source and absorber are NOT identical
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
-v Absorber transition energy shifted no resonant absorption Source
-v Absorber transition energy shifted small resonant absorption Source
-v Absorber transition energy shifted more resonant absorption Source
-v Absorber transition energy shifted more resonant absorption Source
Absorber transition energy shifted v = 0.0 less resonant absorption Source
-v Absorber transition energy shifted smallresonant absorption Source
-v Absorber transition energy shifted no resonant absorption Source
-v Absorber transition energy shifted no resonant absorption Source
-v Absorber transition energy shifted no resonant absorption Source
“Isotope shift” Doppler energy shifted
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
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
move source with constant acceleration -v +v Source Detector x Absorber m-sublevels Es* 0.0 57Fe
= 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
Source Detector x Absorber m-sublevels Es* 0.0 Possible absorption transitions
m-sublevels Possible absorption transitions 6 4 2 5 3 1
Possible absorption transitions Compare these predictions with the measurements… …follow guidelines in Problem. 10.C. and eventually determine
The Pound-Rebecca Experiment Be prepared to explainwhat the experiment discoveredandhow the Mossbauer resonant photon absorption was essential to the measurement.
m-sublevels Possible absorption transitions Case1 6 4 2 5 3 1
m-sublevels Possible absorption transitions Case2 5 3 1 6 4 2
6 5 3 4 2 1 Possible absorption transitions m-sublevels Case3
6 5 4 3 2 1 Possible absorption transitions m-sublevels Case4