Techniques studying polymers - Seoul National...
Transcript of Techniques studying polymers - Seoul National...
Chapter 2.Chapter 2.Techniques for studying
polymers
Characterization of Polymersy
Thermal analysis
Microscopy
SpectroscopySpectroscopy
Diffraction or scatteringDiffraction or scattering
Density measurement and etc…y
Thermal analysisy
-Thermal analysis for BULK samples
Differential scanning calorimeter (DSC)Differential thermal analysis (DTA)y ( )
Thermal gravimetric analysis (TGA)Thermal gravimetric analysis (TGA)
-Typical amount of sample for DSC: 1~10 mgTypical amount of sample for DSC: 1 10 mg
-Is it available in thin film analysis? Absolutely NOT
Microscopypy
Optical Microscopy
Scanning Electron Microscopy
Transmission Electron Microscopy
Scanning Prove Microscopy
Electron MicroscopyElectron Microscopy
• SEM – Secondary electron
imicroscopy
• TEMTransmission electron– Transmission electron microscopy
Acquiring surface image(Microscopy)
Scanning Electron Microscopy
Scanning Electron Microscopy (SEM)Scanning Electron Microscopy (SEM)
SEM vs OMSEM vs. OMSEM Optical microscope
Source of light electron beam wavelength: 2000~7500Awavelength : 0.064~
Medium vacuum air
Lens elect on lens optical lensLens electron lens optical lens
Resolution limit 30A~10A visible : 2000Aultra : 1000Aultra : 1000A
Focal depth 30 about 0.1Magnification 10~30 000 10~2000Magnification 10~30,000 10~2000 Kinds of phase secondary&reflec. Transmitted or reflected
Electron beam lithography
20 um
EBL Plasma EtchHSQ resist
g p y
20 um
e- e- e- e- e- 7
Silicon substratespin coat resist trim
e e e e e 7nm
exposure silicon etch10 HOURS!!10 HOURS!!
develop resist strip
80nm line70nm space
11nm 30nmdiameter
Transmission Electron Microscopy
• High e Energy (100~300keV)• Thin specimen (<2000Å)• Thin specimen (<2000Å)• Transmitted beam – bright
fieldfield• Diffracted beam – crystal
structurestructure• Very high resolution (0.15nm)
Thin section preparationThin section preparation
Ion milling법을 이용한 cross section 시료 제작Ion milling법을 이용한 cross-section 시료 제작
Scanning Prove Microscopy
Scanning Probe Microscopy
CNT on electrodesCNT on electrodesCNT on electrodesCNT on electrodes
Scanning Probe Microscopy
Spectroscopyp py
-Analysis for chemical structure identification
-Difference between scattering and spectroscopy?
-Rayleigh scattering
-UV/VIS, IR, Raman scattering
NMR spectroscopy
Scatteringg
-Structure analysis via
Small angle or wide angle x-ray scattering
Neutron scattering
Light scattering
X‐ray Scatteringy g
- Small angle or wide angle x-ray scattering
Wavelength of incident x-ray:
Small angle vs. wide angle:
Not only for bulk materials but also for films
elastic scattering: ki=kfelastic scattering: ki kf
ki kf
dd
2f t ti i t f 2k kfor constructive interference: 2k s k⋅ =
2 sinn dλ θ= 2 sinn dλ θ=
Synchrotron Radiation Facility
Storage ring at PLS
Pohang Light Source
LINAC Storage ring
just before front-end
Neutron Scatteringg
- Elastic vs. inelastic or quasi-elastic scattering
Wavelength:
Unique features of neutron beam:
Spallation Source: IPNS (Argonne National Lab, USA)
Neutron Reactor: NIST (USA)
Confined building
Guide hall
Sample stage
Detector chamber
Detector chamber (1)
Detector chamber (2)
Neutron Scatteringg
- Elastic vs. inelastic or quasi-elastic scattering
Wavelength:
Unique features of neutron beam:
elastic scattering: ki=kfelastic scattering: ki kf
ki kf
dd
2f t ti i t f 2k kfor constructive interference: 2k s k⋅ =
2 sinn dλ θ= 2 sinn dλ θ=
Scattering pattern of nanocrystal
Background of scattering
elastic scattering: ki=kfelastic scattering: ki kf
ki kf
dd
2f t ti i t f 2k kfor constructive interference: 2k s k⋅ =
2 sinn dλ θ= 2 sinn dλ θ=
( ) ( ) ir qA q r e drρ − ⋅= ∫
u( ) ( )* ( )r r z rρ ρ=FT
( ) ( ) ( )A q F q Z q=SLDD Scattering amplitude
∫
IFTForm factor lattice factor
uarin
g
X squ
*
( )( ) ( )
I qA q A q= ⋅
( )I q
for n atomic crystal
( ) ( ) ( )f∑ ∑
for n atomic crystal,
nj j( ) exp( ) exp( )j n
F q f iq r iq R= − ⋅ − ⋅∑ ∑
unit cell structure factor lattice sumPosition determination
2 integernq R π⋅ = ×
∑th i
nexp( ) ~n
iq R N− ⋅∑since
( ) 1i R∑otherwise, nexp( ) ~ 1n
iq R− ⋅∑
Real and inverse lattice
2 integerr q π⋅ = × (Laue condition ~ Bragg Law)
b b b2 32 a ab ×
1 1 2 2 3 3q v b v b v b= + +1 1 2 2 3 3r u a u a u a= + +
i j ij2
when 0
b a
i j
πδ⋅ =
≠
2 31
2 3 1
2ba a a
π=⋅ ×3 12 a ab × when , 0
when , 2i ji j π≠=
3 12
3 1 2
2ba a a
π=⋅ ×
a a×1 23
1 2 3
2 a aba a a
π ×=
⋅ ×
( )1 1 2 2 3 32r q u v u v u vπ⋅ = × + +
3b
a3a
2a
1a
Structure factor for a uniform sphere
[ ]2( ) ( )P F ρ~ 0ρ2 s qπ =
[ ]( ) ~ ( )P q F q ρ2R
( ) ( ) ( )F i d∫( ) ( ) exp( )F q r iq r drρ= − ⋅∫
Structure factors for several structures
Thin rod
At a certain orientations Θ a
4 cos( ) sin( )2
qLF qL
Θ=
Θ
At a certain orientations, Θ
Lcos 2qL Θ L
V=aLV aL
Circular disk
R1(2 )2( ) 1 J qRP q ⎡ ⎤
= −⎢ ⎥F 2 2( ) 1P qq R qR
= ⎢ ⎥⎣ ⎦
F
Structure factors for several structures
Circular disk
R
⎡ ⎤12 2
(2 )2( ) 1 J qRP qq R qR
⎡ ⎤= −⎢ ⎥
⎣ ⎦q q⎣ ⎦
How about this?--synthetic polymer, DNA, protein…synthetic polymer, DNA, protein…
[ ]2( ) ~ ( )P q F q
constant form factor?
Random coil 2 2 2 2exp( ) 1R R+Or Gaussian coil4 4
exp( ) 1( ) ~ 2 g g
g
q R q RP q
q R− − +
g
htt // i t / / / df/ l t t dfhttp://www.ncnr.nist.gov/programs/sans/pdf/polymer_tut.pdf