Mössbauer Effect

200582116 J-H. Kim 2005. 12. 05

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Contents

Motivation - Beginning - Mössbauer Effect(Ir-191) Experiment - Mössbauer Measurements Summary

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Motivation Applications Summary What is the Mössbauer effect ?

Before the Mössbauer theory Yes~!

I am a nuclei at ground state.

I am a nuclei excited 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.

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Motivation Applications Summary What is the Mössbauer effect ?

Before the Mössbauer theory. Momentum conservation.

Doppler 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.

E # For Ir-191 (hν = 129 keV) v = 202 m/s

’

= 128.999912874 keV ΔE= 8.71E-5 keV Γ = 3.22E-8 keV (natural line width) ΔE ≫ Γ 4

Motivation Applications Summary 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 5

Motivation Applications Summary What is the Mössbauer effect ?

Beginning with the Mössbauer theory I am a nuclei at ground state.

I am a nuclei excited state.

I am K-U.Choi nuclei.

I can give you an energy for your exciting.

I have a different flavor than yours. Really? but.. I don ’ t believe you. -_-;; K-U.Choi stick me on this space with silicon! so I can have little momentum.

Really? I believe you then. 6

Motivation Applications Summary 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

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) # For Ir-191 (hν = 129 keV) N=2700, v = 7.5 cm/s, E

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= 128.99999999

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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 7

Motivation Applications Summary How to measure the M össbauer effect .

Measurement for Mössbauer effect.

Equipment Intensity Data 0 ΔE Source.

Absorber.

Detector.

0 Velocity 8

Motivation Applications Summary 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.

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Motivation Applications Summary 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. 10

Motivation Applications Summary 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 11

Motivation Applications Summary 3. The hyperfine structure.

The nuclear isomer shift.

The nuclear Zeeman effect.

The nuclear quadrupole splitting.

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Motivation Applications Summary 3. The hyperfine structure.

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Motivation Applications Summary 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. 14

Thank you.

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