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MMöössbauer ssbauer EffectEffect

200582116200582116

J-H. KimJ-H. Kim

2005. 12. 052005. 12. 05

22

MotivationMotivation

- Beginning- Beginning

- Mössbauer Effect(Ir-191)- Mössbauer Effect(Ir-191)

Experiment Experiment

- Mössbauer Measurements- Mössbauer Measurements

SummarySummary

Contents

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Before the Mössbauer theory Before the Mössbauer theory

What is the Mössbauer effect ?

I am a nuclei excited state.

I am a nuclei at ground

state.

I want to go to the excited

state.

You will be unstable. Do you want it?

Ok. I will give you a gamma ray for your

exciting.

Thank you!

This energy is not enough for my exciting.

The energy of my gamma should be

smaller than excited since I

should be recoiled.

Motivation Applications Summary

Yes~!

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Before the Mössbauer theory. Before the Mössbauer theory.

What is the Mössbauer effect ?

- The nuclei recoil back with velocity v(βc).

- The frequency of gamma ray for absorption is lower than at the emission.

=> Then target nuclei cannot absorb the gamma energy. # 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

Momentum conservation.

Doppler effect.

Motivation Applications Summary

55

BeginningBeginning

- Rudolf Mössbauer.(1929~?, German - Rudolf Mössbauer.(1929~?, German physicist)physicist)

- Discovered the - Discovered the recoil-freerecoil-free emission and emission and absorption of gamma rays by nuclei. (in absorption of gamma rays by nuclei. (in 1958)1958)

- Win the Novel prize. (in 1962)- Win the Novel prize. (in 1962)

Experiment ( Recoil Free Nuclear Radiation )Experiment ( Recoil Free Nuclear Radiation )

- Ir-191- Ir-191

How atom can recoil-free emission and How atom can recoil-free emission and absorption?absorption?

- - Atoms Atoms are held tightly in crystalline are held tightly in crystalline

atomic structuresatomic structures

What is the Mössbauer effect ?

Motivation Applications Summary

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Beginning with the Mössbauer theory Beginning with the Mössbauer theory

What is the Mössbauer effect ?

I am a nuclei excited state.

Really? but.. I don’t believe

you. -_-;;

Really? I believe you

then.

I am a nuclei at ground

state.

I can give you an energy for your exciting.

I am K-U.Choi nuclei. I have a different flavor

than yours.

Motivation Applications Summary

K-U.Choi stick me on this space with silicon! so I can have little momentum.

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Beginning with the Mössbauer theory. Beginning with the Mössbauer theory.

What is the Mössbauer effect ?

- 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

Motivation Applications Summary

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Intensity

Velocity0

ΔE0

Measurement for Mössbauer effect.Measurement for Mössbauer effect.

How to measure the Mössbauer effect.

Source.Absorber

.

Detector.

Equipment Data

Motivation Applications Summary

99

What can we measure with Mössbauer effect?What can we measure with Mössbauer effect?

Applications.

1. The lifetime determinant for an excited 1. The lifetime determinant for an excited particle.particle.

2. Nuclei energy level.2. Nuclei energy level.

3. The general relativity theory. 3. The general relativity theory.

- Gravitational red shift.- Gravitational red shift.

4. The hyperfine structure.4. The hyperfine structure.

- The nuclear isomer shift.- The nuclear isomer shift.

- The nuclear Zeeman effect.- The nuclear Zeeman effect.

- The nuclear quadrupole splitting.- The nuclear quadrupole splitting.

Motivation Applications Summary

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Particle lifetime of an excited state in a nucleus.Particle lifetime of an excited state in a nucleus.

1. The lifetime determinant for an excited particle.

- τ=Δt : particle lifetime.- τ=Δt : particle lifetime.

- ΔE(Γ/2) : - ΔE(Γ/2) : can be determined can be determined in Mössbauer experiment.in Mössbauer experiment.

The Breit-Wigner distributionThe Breit-Wigner distribution : :

Γ : natural line width.Γ : natural line width.

x axis : energyx axis : energy

y axis : absorption cross section. y axis : absorption cross section.

Motivation Applications Summary

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Gravitational red shift.Gravitational red shift.

2. The general relativity theory.

- E_0 = hν = 14.4 keV- E_0 = hν = 14.4 keV

- Gravitational red shift.- Gravitational red shift.

ν=ν_0(1+(gh/c^2))ν=ν_0(1+(gh/c^2))

ΔE=2*ν_0(gh/c^2)ΔE=2*ν_0(gh/c^2)

Motivation Applications Summary

ΔE

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The nuclear isomer shift.The nuclear isomer shift.

3. The hyperfine structure.

Motivation Applications Summary

The nuclear Zeeman effect.The nuclear Zeeman effect.

The nuclear quadrupole splitting.The nuclear quadrupole splitting.

1313

3. The hyperfine structure.

Motivation Applications Summary

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What is the Mössbauer effect?What is the Mössbauer effect?

Summary

Motivation Applications Summary

How to measure the Mössbauer effect.How to measure the Mössbauer effect.

ApplicationsApplications

1. The lifetime determinant for an excited particle.1. The lifetime determinant for an excited particle.

2. The general relativity theory.2. The general relativity theory.

3. The hyperfine structure. 3. The hyperfine structure.

1. Gamma-ray source, an absorber, Gamma Detector.1. Gamma-ray source, an absorber, Gamma Detector.

2. Relative velocity of varying the gamma-ray energy.2. Relative velocity of varying the gamma-ray energy.

For nuclei in crystalline atomic structures, the gamma radiation For nuclei in crystalline atomic structures, the gamma radiation emitted from the nuclei are approximately recoil-free.emitted from the nuclei are approximately recoil-free.

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Thank you.