X -Ray Interface Science

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