nuclear resonant scattering (nrs) and its applications

Nuclear Resonant Scattering (NRS)and its Applications using pulsed SR

Feb 28, 2005Dr. Zhang Xiaowei

Why Nuclear Scattering usingSynchrotron Radiation?

1) Obtain an ultra-monochromatic x-ray beam:a frontier of energy resolution

2) Develop some new experimental techniques: inelastic, quasi-elastic x-ray scattering

3) Develop new possibility of traditional Mössbauerspectroscopy4) Develop applications of ultra-

monochromatic x-ray beam: x-ray wavelengthstandard

γ-ray vs. synchrotron radiation

ideallyΔE~100µeVEnergytunability

ideallydifficultPulsed radiation

ideallypoor or difficultPolarization

>1051Relativebrilliance

10-3~10-2eV10-8eVEnergybandwidth

SRγ-ray

Overcome a huge S/N

forbiddenallowedlySpecialized

opticaldevice

E1M1, E2Polarizationdependence

Prompt responseTime-delayedresponse

Time gateddetection

Noise (Electricscattering)

Signal (Nuclearscattering)technique

Ultra-monochromatic x-raybeam can only be obtainedfrom a nuclear system insolid, can not be obtainedfrom any electric systems.

Resolution power ofdiffraction lattice is limited byerror of Δd/d.

Nature of nuclei frequencyresonance in x-ray range(Mössbauer resonance) is akey technique of Ultra-monochromatic x-ray beam.

To separate nuclear resonantsignal from electric scattering,the difference in behavior ofpulse response is utilized.

10-0

10-1

10-2

10-3

10-4

10-5

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!E/E

10-0101 102 103 104 105 106 107 108 109100

filter/tuner

!!""##$

SSD

Mössbauer$%#%&"'$%'%#

10-19

10-18

10-17

10-16

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& $#%

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&+"-.

Dopplar shift

multilayer,grating

Scale of energy resolution

crystal diffraction

high-resolution

NaI detector

principle and operation in ElectromagneticWaves Spectroscopy

wave length (m)

frequency (Hz)

106

(1MHz)109

(1GHz)1012

(1THz)1015

(1PHz)1018

(1EHz)1021

c = !!, k = 2" / !, # = 2"!

1Å105 103

(1km)1

(1m)10-3

(1mm)10-9

(1nm)10-12

(1pm)

10-15

(1fm)

LF MF HF VHF UHF SHF EHF

10-6

(1µm)

1eV 1keV 1MeV

x-ray $-ray

Wave: A(t)exp(i(#t-k•r))P

band-pass filter, an electronic instrumentation

cavity resonator monochromatordispersion material, grating, crystal lattice

continuous or pulsed wave

# k"!#!! !

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Unified point of view on spectroscopy of electromagnetic wave:Spectrometer operates on ω in long wavelength range, operates on k(= ω /c) in high frequency range.

Frequency tuning in radio-wave band!"#$%&'(

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y(t) = g(t – !)x(!)d!

–"

t

= g(t – !)x(!)d!–"

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, when t – ! < 0, g(x) = 0

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InputOutput

Instrument

Mathematical description

t-space

ω-space

Spectrometer for light or x-ray

3-dimensional view of light source

Y1(!)Y

2(k) = G

1(!)G

2(k)X

1(!)X

2(k)

Y(!, k) = G1(!)G

2(k) X(!, k)

Y (!, k) = G(!, k)X(!, k)

脉冲 !

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Pulsed wave

Point source

Continuous wave

Finite extension source

Pulsed wave я Point source

Continuous wave я Finite extension source

Study of resonant system essentially needs a short pulsed wave я δ function response

Few bunches э High-brilliance in time domain

Correlations between NRS in energydomain and time domain

NRS Amplitudef(!, k)F(t, k)

Fourier transform

"-ray

!f(!, k)

pulsed SR

F(t, k) !

NRS Amplitude

NR time spectraNR energy absorption spectra

optical theorem

#"!#$%&

#"!#$%&k/4$ Im(f)

power spectrum

Fourier transform Energy difference of hyperfine levels

Theoretical level

Experimental level

Nuclear resonant absorptionspectra in energy domain(Mössbauer spectra)

Nuclear resonant responsefor short x-ray pulse(Quantum beats)

Fourier transformation ofquantum beats (Powerspectra, energy differencebetween energy levels)

Comparing nuclear resonance in 3 worlds

Develop a new experimental technique

configuration of inelastic scattering using NRS

high-resolution monochromator

sample containing NR element

detect time-delayed NRS signal

!

high-resolution monochromator

sample

detector

detector

detector

detector

Foil containing NRS element

monochromator

analyzer

standard configuration of inelastic scattering

detector

sample

First result of inelastic NRS

Develop new applications of traditionalexperimental technique

Control x-ray penetration depth

conclusion• 1) not a simple short bunch, but high-brilliant

short pulse• 2) NRS technique brings us a new energy

resolution frontier in x-ray region• 3) NRS technique combines with pulsed SR let us

be able to do something new where the traditionalMössbauer spectroscopy can not do