Upload
hammer
View
111
Download
0
Tags:
Embed Size (px)
DESCRIPTION
CERN. Synchrotron Radiation based TDPAC. I. Sergueev European Synchrotron Radiation Facility Grenoble, France. ESRF. Outline. SR TDPAC: comparison with conventional TDPAC SR TDPAC: comparison with MS and NRS Examples of application: Site-specific phonon dynamics - PowerPoint PPT Presentation
Citation preview
Synchrotron Radiation based TDPACI. Sergueev
European Synchrotron Radiation FacilityGrenoble, France
HFI / NQI 2010, 12-17 September 2010 CERN
ESRF
CERN
Outline
• SR TDPAC: comparison with conventional TDPAC •SR TDPAC: comparison with MS and NRS
• Examples of application:
• Site-specific phonon dynamics
• Relaxation in glasses
• Study of QI in -tin
• Conclusion
HFI / NQI 2010, 12-17 September 2010 CERN
Nuclear Resonance Scattering
HFI / NQI 2010, 12-17 September 2010 CERN
ground state
excited state
life time of the excited state - 0
absorption re-emission
Time
0 200 ns
Time
A.Q.Baron et al, Europhys. Lett.,34, 331(1996)
I.Sergueev et al, Phys. Rev. B 73, 024203 (2006)I.Sergueev et al. Phys. Rev. B 78, 214436 (2008)
TDPAC vs SR TDPAC
HFI / NQI 2010, 12-17 September 2010 CERN
1
2
β-,β+,EC
TDPAC
1 2
SRPAC
1 2
sample(-source)
counterstart stop
detector 2
12 detector
SR
start stopcounter
sample
Advantages of SR TDPAC:•no chemical or electronic aftereffects•only one nuclear transition•in general, large contrast of the beats
dete
ctor
1
Formal description of SR TDPAC for M1
HFI / NQI 2010, 12-17 September 2010 CERN
Z
kin
kout
Z
k1
k2
TDPAC
)()(cos1)( 22222/ tGPAetI t )()(cos21)( 22222
/ tGPAetI t
Isotope transition 2A22
57Fe, 119Sn 1/23/21/2 0.5
61Ni, 155Gd 3/25/23/2 0.28
121Sb, 151Eu
5/27/25/2 0.22
99Ru 5/23/25/2 0.02
SR TDPAC
SR TDPAC on 57Fe
HFI / NQI 2010, 12-17 September 2010 CERN
Z
kin
kout
0 50 100 150
200
400
600
Time / ns
Inte
nsity
/ co
unts
200
400
600
200
400
600
Sample: ferrocene enriched by 57Fewith quadrupole splitting
ttG cos)( 54
51
22
)()(cos21)( 22222/ tGPAetI t
Sample: α-iron enriched by 57Fewith magnetic splitting
0 100 200 3000
100
Inte
nsi
ty /
counts
Time t / ns
Z
kin
kout
B
)(21)( 22/ tRAetI t
ttR B2cos)( 43
41
1 2
3
1
2
3
SR TDPAC for E2 transition
HFI / NQI 2010, 12-17 September 2010 CERN
Nuclear transition : 0+ 2+, Cascade: 0 2 0
0 1 2 3 4 5 60
1
2
Rela
tive Inte
nsi
ty
Time t / ns
166ErFe6Sn6
D. H. Ryan and J.M.Cadogan, Hyp. Int. 153 (2004) 43
)4cos)(cos)(cos()(
)(cos)(21)(
)4(424
1444444
1
22222/
PPtGA
PtGAetI t
Experimental setup
HFI / NQI 2010, 12-17 September 2010 CERN
Monochromator
High ResolutionMonochromator
Al foilUndulator
Sample
Detector
Detector
beam
Detector with Si APDs
APD
Dynamical range: ~106 ph/sTime resolution: ~0.1-2 ns
Energyband width:
1-30 meV
SR TDPAC vs NFS
HFI / NQI 2010, 12-17 September 2010 CERN
k0
t = 0 t = 0
k0
k1
t > 0
nuclear bragg diffraction
single nucleus scatteringSR TDPAC
k0
t > 0
coherent scattering in forward direction -
- nuclear forward scattering
Optical theorem:
t f wd( ) I m Fourier f (t) MS total cross-section
NFS amplitude
Differences:• dependence on the spatial evolution of nuclei• dependence on the ground nuclear state spin evolution
Hyp. Int.: quadrupole splitting
0 200 400 600
NFS
I(t)
Time t (ns)
SR TDPAC
-2 0 2 Velocity [ mm/s ]
Rela
tive
tra
nsm
issi
on
MS
i t i tE e e
Coherent superposition of the wavelets
I=3/2
I=1/2
Energy level diagram: 57Fe, quadrupole splitting
|m|3/2
1/2
1/2
Ferrocene
HFI / NQI 2010, 12-17 September 2010 CERN
Hyp. Int.: 2 single lines
0 200 400 600
NFS
I(t)
Time t (ns)
SRPAC
-2 0 2 Velocity [ mm/s ]
Rela
tive
tra
nsm
issi
on
MS
I=3/2
I=1/2
SR TDPACMS, NFS
HFI / NQI 2010, 12-17 September 2010 CERN
Hyp. Int.: magnetic splitting
0 100 200 300
NFS
Log
I(t)
Time t [ ns ]
SR TDPAC
-8 -4 0 4 8 Velocity [ mm/s ]
Rela
tive
tra
nsm
issi
on
MS
-ironm
+3/2+1/2-1/2-3/2
-1/2+1/2
MS, NFS
SRPAC
HFI / NQI 2010, 12-17 September 2010 CERN
SR
SR TDPAC
NFS
Applications
• Site-specific phonon dynamics
• Relaxation in glasses
• Study of QI in -tin
Phonon assisted SR TDPAC
HFI / NQI 2010, 12-17 September 2010 CERN
Weber, H., Hafner, S.S.: Z. Krist. 133 (1971) 331.
A site: tetrahedral, B = 49.0 T
B site: octahedral, B = 46.0 T
Handke B et al., Phys. Rev. B 71 (2005) 144301Sample:Magnetite, Fe3O4
Phonon assisted SR TDPAC
HFI / NQI 2010, 12-17 September 2010 CERN
)(21)( 22/ tRAetI t
)2cos()2cos()( 43
41
43
41 tBtAtR BA
B site
A site
16 meV22 meV
35 meV
0
1
A=0.5, B=0.5
A=0.6, B=0.4
A=0.8, B=0.2
0
1
Ani
sotrop
y
0 50 100 150 2000
1
Time / ns
Relaxation in glasses
HFI / NQI 2010, 12-17 September 2010 CERN
EFG
ferrocene Fe(C5H5)2
Sample:
Glass-former:Di-butyl phthalate, Tg = 178 K
Task: resolve rotational and translational degrees of motions
Relaxation in glasses
HFI / NQI 2010, 12-17 September 2010 CERN
Relaxation process
a aα
α
λ
k – jump rate, sec-1
a – jump distanceα – jump angleλ – wave length, 0.86 AR – radius of the molecule, 2 A
22
32
akT
223 kR
R
a 3
2
03.02
232
RT
R
Relaxation in glasses
HFI / NQI 2010, 12-17 September 2010 CERN
1000
2000
1000
2000
1000
2000
Inte
nsity
T = 180 K
1000
2000
500
0 100 200 300 400 500 600101
102
Time / ns
T = 280 K
102
103
101
102
T =205 K
Inte
nsity
0 100 200 300 400 500 600100
101
102
103
T =215 K
Time / ns
T =180 K
Sample:
Di-butyl phthalate, Tg = 178 K
Di isobytyl phthalate, Tg = 188 K5% ferrocene +
DiBP+FCSR TDPAC
DiBP+FCNFS
SR
SR TDPAC
NFS
Relaxation in glasses
HFI / NQI 2010, 12-17 September 2010 CERN
140 160 180 200 220 240 260 280 300
105
107
109
SR TDPAC NFS + MS
NR
S d
ampi
ng /
s-1
Temperature / K
DS
rat
e / s
-1
105
107
109
dielectric spectroscopy J .Phys.Chem.B 108(2004)4997
140 160 180 200 220 240 260 280 300
105
107
109
NR
S d
ampi
ng /
s-1
Temperature / K
SR TDPAC NFS + MS
105
107
109
DS
rat
e / s
-1
dielectric spectroscopy J .Phys.Chem.B 108(2004)4997
DBP+FC DiBP+FC
Conclusions:The probe reproduces the dynamics of the glass former.At low T dynamics of the probe follows slow β branchAt low T only molecular rotation is seen in both NFS and SR TDPAC.
Study of -tin by SR TDPACC. Strohm et al., in preparation
K.P.Mitrofanov et al., Sov. Phys. JETP 21 (1965) 524
0 100 200 300 400100
101
102
103
104
Time / ns
90 K
105
Inte
nsi
ty / c
ounts
190 K
104
105
295 K
104
105
573 K
0 100 200
0.8
1.0
1.2
Time / ns
0.8
1.0
1.2
0.8
1.0
1.2
Anis
otropy
0.8
1.0
1.2
Measurements by SR TDPAC
HFI / NQI 2010, 12-17 September 2010 CERN
J.C. Soares et al.,Phys.Lett. 45A(1973)465
Study of -tin by SRPAC
1970 1975 1980 2008
17.5
18.0
18.5
19.0
Deca
y half
time /
ns
Year of measurements
Nuclear Data Sheets value: 1/2
= 18.030.07 ns
Result of SRPAC measurements:1/2
= 18.290.01 ns
Results of measurements
0 100 200 300
0.24
0.26
0.28
0.30
0.32
this measurements previous MS and TDPAC
measurements
Qua
drup
ole
split
ting
/ mm
/s
Temperature / K
Conclusion:•value of the life time of 23.9keV nuclear state of 119Sn was obtained with high precision•quadrupole splitting of -tin have been seen in the time spectrum and was measured for different temperatures
HFI / NQI 2010, 12-17 September 2010 CERN
Conclusion
SR TDPAC – method which allows to extend study of hyperfine interactions by TDPAC on to Mössbauer isotopes
– method which allows to extend study of hyperfine interactions by MS into the range of zero Lamb-Mössbauer factor.
3 main directions of application:
Complementary to MS information about hyperfine splitting and dynamics
Hyperfine interactions in high energy Mössbauer isotopes
Study of hyperfine interactions and dynamics in soft condensed matter
HFI / NQI 2010, 12-17 September 2010 CERN
Acknowledgment
HFI / NQI 2010, 12-17 September 2010 CERN
• U. Van Bürck – TU München, Germany• G. Smirnov – Kurchatov Institute, Moscow, Russia
Members of ESRF nuclear resonance group:• R. Rüffer• A. Chumakov• T. Asthalter• C. Strohm•T. H. Deschaux-Beaume