small angle x-ray scattering · small angle x-ray scattering christopher j. tassone stanford...
TRANSCRIPT
Small Angle X-ray Scattering
Christopher J. Tassone
Stanford Synchrotron Radiation Lightsource
Materials Science Department
7th Annual SSRL Scattering School
An Overview
Outline
Overview of SAXS:
• Beamline Nuts & Bolts
• Calculating q-range
• SAXS Fundamentals and Scattering Patterns
• Real World Science Examples
• Moving into the future
- In-operando
- Probing materials off equilibrium
- In-situ growth
Beamline Nuts and Bolts
Calculating q-range
λ = 2dsin(θ)
Q = 2π/d
Easiest way to do this is to find your q/pixel
D S θpix
Xs-d
Xpix
To do this you need: •Detector Pixel Size
•Sample to detector distance
•Energy of incident x-ray photons
•Beamstop Size
•Detector Size
1) Solve for θpix
θpix = tan-1(xpix/xs-d)
2) Convert θpix to qpix
qpix = 4πsin(θpix)/λ
3) Find first real pixel p1= (rbstop/xpix)
4) qmin= qpix * p1
5) qmax= qpix * pdet/2
SAXS Fundamentals
Fundamentally looking at form factor scattering only:
I(q) = F(q)2Z(q)2
I(Q) = ∫Γn(r)e-iqrdr
Scattering from 1-100 nm density
inhomogeneities
k
2q
incident
scattered
k’
Q
SAXS Fundamentals
Fundamentally looking at form factor scattering only:
I(q) = F(q)2Z(q)2
I(Q) = ∫Γn(r)e-iqrdr
Scattering from 1-100 nm density
inhomogeneities
k
2q
incident
scattered
k’
Q
Understanding SAXS Profiles
• Guinier regime:
gives Rg, which is a measure
for the size of the particles
• Porod exponent:
provides
information about
shape of the
particles
polydisperse in
shape and/or size
Understanding SAXS Profiles
monodisperse in
shape and size
Form factor:
• depends on geometrical
shape of particles
• gives size and electron
density distribution of
particles
Understanding SAXS Profiles
Structure factor:
• Sequence of peaks Symmetry of structure
• Position of peaks Size of structure
• Width of peaks Size of domains/grains
• Intensity of peaks Degree of crystallinity
• Azimuthal distribution of peaks Orientation of domains
periodic
structures
10
Science at Beamline 1-5
Block-co-polymers
Mesoporous Materials
Nanomaterial Synthesis
Nanoparticle Characterization
Batteries/Energy Storage
Catalysts
Energy Generation Materials
11
Science Highlight-BCP Ordering
Rao, et. Al. Adv. Mater. 2010, 22, 5063. www.elitenetzwerk.bayern.de
Can we use BCP for:
• Improved transport in oFETs?
•Membranes for ionic transport?
Organic Electronics •Flexible
•Low cost
•Facile processing
•Light weight
12
Science Highlight-BCP Organization
Understanding BCP Phase Diagram through SAXS
Ho, Victor; Boudouris, B.W.; McCulloch, B.L.; Shuttle, C.G.; Burkhardt, M; Chabinyc, M.L.; Segalman, R.A. “Poly (3-alkylthiophene) Diblock
Copolymers wuth Ordered Microstructures and Continuous Semiconducting Pathways” J. Amer. Chem Soc. 133, 2011, 9270.
13
Science Highlight-BCP Templated Nanoparticle Films
Electrochemical
Charge Storage
TiO2 H2O
OH-
H2O
O2
O2-
CO2
+ Organic
Precursors Catalysts
Photovoltaics
Adv. Mater. 2011, 23, 3144
14
Science Highligh-BCP Templated Nanoparticle Films
Me
erw
in’s
Salt
BC
P
inco
rpo
ration
Film
Co
nd
en
sa
tion
Th
erm
al
Annealin
g
Rauda, I.E.; Saldariaga-Lopez, L.C.; Helms, B.A.; Schelhas, L.T.; Membreno, D.;
Milliron, D.J.; Tolbert, S.H. “Nanoporous Semiconductors Synthesized Through
Polymer Templating of Ligand-Stripped CdSe Nanocrystals.” Adv. Mater. 25, 2013.
1315.
PEO Domain
Aromatic Domain
Inter-domain
spacing
Inter-molecular
spacing
Domain
size
How Does Membrane Morphology Relate to
Ionic Conductivity?
•Use SAXS to characterize nano and
mesoscale morphology as a function of
PEG loading
•Random co-polymer PEO-PI
•Conductivity peaks when PEG loading
is high enough to observe PEO-PEO
domain correlations (20 nm)
Science Highlight-Random co-polymer Membranes
Controlling BHJ Morphology
Thermal
Annealing Increases
crystallinity
Increases phase
segregation
Solvent Additives Increases crystallinity
Increases or decreases phase segregation
More isotropic crystal distribution
No Post Processing
Solvent
Annealing Increases
crystallinity
Increases phase
segregation
Processing Additives Tune Morphology Uniquely
Processing additives… •enhance crystallinity
•increase isotropic distribution
of crystallites
•can increase or decrease
degree of phase segregation
Pure CB DIO
Liang, Y. et. Al. doi:10.1002/adma.200903528
OT Pure oDCB
J. Rogers et al., doi: 10.1021/ja2104747
Y.Yao et. al. doi:10.1002/adfm.200701459
How Does Solution Behavior Effect Solid Film
Formation?
How Does Solution Behavior Effect Solid Film
Formation?
?
Probing Solid State Film and Casting Solution
Solution SAXS
Solid State SAXS
Interpreting SAXS Data
Two Regimes •Guinier domain size
•Porod •Diffuseness of interface
between domains
•Shape of aggregate
Probing Solid State Film
Solution SAXS
Solid State SAXS
Processing Additives Decrease Phase Segregation
-2.7
-3.5
Visualizing Morphologies
Representative 3D morphologies
B. Ingham et al., doi:
10.1107/S00218898110048557
no additive
w/ ClN
w/ DIO
w/ ODT
Probing Casting Solution
Solution SAXS
Solid State SAXS
C16-PDPP2FT Solution Phase Conformation
10-4 10-3 10-2 10-110-3
10-2
10-1
1
101
102
103
104
105
106
Inte
nsi
ty[a
.u.]
q [Å-1]
41 kDa
36 kDa
29 kDa
23 kDa
q-3
q-1
‡‡
†
a)
Low Mn High Mn
b)
10-4 10-3 10-2 10-110-3
10-2
10-1
1
101
102
103
104
105
106
Inte
nsi
ty[a
.u.]
q [Å-1]
41 kDa
36 kDa
29 kDa
23 kDa
q-3
q-1
‡‡
†
a)
Low Mn High Mn
b)
Chloronapthalene has little effect on PCBM Aggregation
Neat CB
Increasing Concentration
Neat CB 5% CN
10-4 10-3 10-2 10-110-3
10-2
10-1
1
101
102
103
104
105
106
Inte
nsi
ty[a
.u.]
q [Å-1]
41 kDa
36 kDa
29 kDa
23 kDa
q-3
q-1
‡‡
†
a)
Low Mn High Mn
b)
Putting Together Polymer and Fullerene Behavior
5% CN
Neat CB
K. Schmidt. Adv. Mater. doi:10.1002/adma.201303622
Mechanism Summary
1. Additive promotes ordering within solution phase aggregates
2. PCBM stays well dispersed in solution with or without additive
3. Films cast with additive show small more intermixed domains
Weakly ordered polymer aggregates act as dispersed seed
sites for crystallization during film formation
30
Enabling Science Through Beamline Upgrades
• Characterization of disordered soft
materials
• Fuel cell membranes
• Organic Photovoltaics
• Bioelectronics
• Anatomical materials
31
Increasing In-situ Capabilities
• Increased in-situ capabilities
• Solution phase reactor
• Electrochemical fluid cell
- Battery materials
- Catalyst materials
- Electrochemical Capacitors
• Stress-strain curves
Dogbone
Force Transducer
32
In-situ Printing at BL 1-5
Print Film
Collect SAXS/WAXS
Extract Metrics
Change Printing
Conditions
Beamline Information
Website:
http://www-ssrl.slac.stanford.edu/content/beam-lines/beam-lines-
by-number (1-5 page under construction)
Deadlines:
Beamtime Requests
November - February scheduling August 20
February - May scheduling November 15
May - August scheduling February 15
New Proposals
Beam time eligibility beginning in February September 3
Beam time eligibility beginning in May December 1
My Info: [email protected]