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.
Ok. I will give
you a gamma ray
for your exciting.
You will be
unstable. Do you
want it?
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.
# 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
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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
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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 can give you an
energy for your
exciting.
I am K-U.Choi nuclei.
K-U.Choi stick me
on this space with
silicon! so I can
have little
momentum.
Really? but..
I don’t believe
you. -_-;;
I have a different
flavor than yours.
Really? I believe
you then.
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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’)
# 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
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Motivation
Applications
Summary
How to measure the Mössbauer effect.
Measurement for Mössbauer effect.
Data
Equipment
Source.
Intensity
0
ΔE
Detector.
Absorber.
0
Velocity
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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.
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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
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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.
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Thank you.
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