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X -Ray Interface Science. Michael Bedzyk Materials Research Science and Engineering Center ( MRSEC ) Institute for Catalysis in Energy Processes (ICEP ) International Institute for Nanotechnology (IIN) Center for Electrical Energy Storage (CEES) Synchrotron Research Center (SRC). - PowerPoint PPT Presentation
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X-Ray Interface ScienceMichael Bedzyk
Materials Research Science and Engineering Center (MRSEC)Institute for Catalysis in Energy Processes (ICEP)International Institute for Nanotechnology (IIN)Center for Electrical Energy Storage (CEES)Synchrotron Research Center (SRC)
Funding: NSF, DoE, Airforce
X-rays: APS, NU X-ray Lab, ESRF
Group Party June 2013
Group breakdown: 2 postdocs, 7 graduate students
Bedzyk Group Overview: Atomic Scale View of Interfacial and Nanoscale Processes with X-Rays
X-ray Scattering and Absorption Studies of Au Nanostructures for DNA Functionalization and
Assembly
C3-SH
A10
18bp duplex Au
0 2 4 6 8 10
-0.5
0.0
0.5Ag EXAFS
Overgrown sample Ag As Synthesized sample Ag
k (A-1)
k2 *chi
(k)
25500 25525 25550 25575 25600
0
1
Ag XANES
AgBr Nanorod sample Ag Overgrown sample Ag Ag foil
norm
. abs
orpt
ion
(A.U
.)
E (eV)
X-ray Standing Wave studies
of graphen
e
DNA-NP Schematic
Nanorod growth and functionalization
Ion distribution around DNA-NPs
Incidence X-ray, 18-20 keV
In-situ interfacial structural studies of SEI formation
Nanostructured Electrodes for High Rate Li-ion Batteries
In-situ X-ray reflectivity structural studies of lithiation in anode materials
Nanoscale Electrodes for Li-Ion Batteries
Some X-ray Basics: Wave Property Structural Info λ = 0.1 to 10 Å wavelength E-M radiation X-rays scatter coherently from electrons
Particle Property Compositional Info Eϒ = 1 to 100 keV energy Photo effect: Inner shell (K, L) ionization XRF : Decay of excited ion to ground state by characteristic XRF emission
X-ray VisionAdvantage: Weak interaction with matter High penetrating power
In situ analysis Buried structures
Atomic-scale resolution
Problem: Weak interaction with matter weak signal
Need very intense X-ray source
Brightest X-ray Source in Western Hemisphere
= Advanced Photon Source
relativistic electrons pass thru periodic magnetic array
Undulator Device
Argonne National Laboratory
NU
ANL
ORD
NU-ANL Carpool
Funded by US Dept. of Energy Lab
Simultaneous SAXS-MAXS-WAXS at DND-CAT/APS
Capillary Tube with flowingSample Solution
3 CCD Areal Detectors
SAXS
MAXS
WAXS
Incident X-ray Beam
$1.2 M, Just completed Upgrade
Self-assembled systems of amphiphiles
Critical packing parameter = V/AL
Spherical micelle
Fiber
Curvedmembrane
Planar membrane
hydrophilichydrophobic
AV L
Applications
Template for synthesis, tissue regeneration…..
Drug delivery
Gene therapy
Cell model
Photovoltaic cells
Mimvirus(~200 nm across)
HIV virus(~150 nm across)Mouse Polyoma Virus
(~50 nm)
Crystalline lipid vesicle(~1 mm across)
(Dubois, et al., Nature 2001)
spherical
icosahedral
Shells of different shapes
-Walby’s archaea organism-hexagonal lattice
(W. Stoeckenius J. BACTERIOLOGY, (1981))
(Iancu, et al., J. Mol. Biol. (2010) 396, 105–117)
-size and shape variability of cellular carboxysomes
100 nm
- Mixed component system
- Fluid Membranes (no internal order):
Young’s modulus (Y) = 0Bending rigidity (κ)
- Crystalline membranes (with internal order): Young’s modulus > 0
+cation anion
Catanionic self-assembled membranes
cones cylinders
+ -
Cation aloneCation + anion mixture
500 nm
100nm
500 nm
Quick-freeze deep-etch TEM microscopy images
( ) ( )v
A e d q rq r r
2( ) ( )I Aq q
X-ray
Fourier Transform4 sinq
q (nm-1)
SAXS - 1-100 nm scale features - size and shape
WAXS - molecular packing - crystal structure
I
Small/ Wide Angle X-ray Scattering (SAXS/ WAXS)
2dq
2
Do an angle averaged integration
2D images from SAXS
2
34567
1
2
3456
norm
alize
d inte
nsity
0.01 2 3 4 5 6 7 8 9 0.1 2
q(A-1)
1D graph of intensity vs q
q (Å-1)
X-Ray
Vesicles or membranes flowing freely in solution
SAXS/WAXS Data Processing
+3 Cation and -1 anion mixture vesicles Porod Power Law
α = 2 2D platelet
5.3 nm Fit the data with a bilayer model to obtain thickness
Model fit of bilayer structure
3.8 nm
2.1 nm
cation
Cation only
+3 Cation and -1 anion mixture vesiclesCation alone
α = 2
Hexagonal lattice
Area/ molecule = 0.197 nm2
0.477 nm
Electrostatic attraction induces crystallization of tails
WAXS
Packing of tails 19
Molecular packing within membrane
d = 2π/q = λ/2sinθ = 0.413 nm
- Crystal structure can change morphology
- Molecule flow rate across membrane can be controlled by packing density and membrane thickness
- Hydrophobic drugs encapsulated inside membrane
20
Why do we want to control membrane crystal structures?
- Can we control the crystal structure?
- Can we control the shape of the vesicles or membrane morphology?
Play with electrostatics!
• Change pH to change effective charge of head groups.
• Change tail length to change dipolar van der Waals attraction
21
Questions
What a new student in the Bedzyk group might expect to be involved with while pursuing their
PhD • Gain an expertise with general x-ray techniques and
experimental design
• Learn fundamental materials science/ chemistry/ physics/ biology relevant to the systems they are studying (interdisciplinary research)
• Take measurements at the Advanced Photon Source and help develop the Dupont-Northwestern-Dow beamline (sector 5)
• Understand atomic-scale structure and how it applies to desirable materials properties