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)

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 *c

hi(

k)

25500 25525 25550 25575 25600

0

1

Ag XANES

AgBr Nanorod sample Ag Overgrown sample Ag Ag foil

no

rm. a

bso

rpti

on

(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 Vision

Advantage: 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

hydrophilic

hydrophobic

A

V 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)

sphericalspherical

icosahedralicosahedral

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) = 0

Bending 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 sin

q

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)

2d

q

2q

Do an angle averaged integration

2D images from SAXS

2

3

4567

1

2

3

456

norm

aliz

ed in

tens

ity

0.012 3 4 5 6 7 8 9

0.12

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