in real and reciprocal space? - Brookhaven National Laboratory · in real and reciprocal space? NSLS-II Workshop February 11, ... NSLS-II_ade_Feb_2008.ppt NC STATE University 11

NSLSNSLS--II_ade_Feb_2008.pptII_ade_Feb_2008.ppt

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Spatial resolution and spectroscopy: The ultimate “cross-over” tool

in real and reciprocal space? NSLS-II Workshop

February 11, 2008

H. Ade

Department of Physics

North Carolina State University

http://www.physics.ncsu.edu/stxm/

Thanks to J. Stoehr, G. Mitchell, for their viewgraphs/data

and many other colleagues, collaborators, and users

Thanks to organizers for invitation

and NSF, DOE, Dow Chemical for financial support over the years


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Goal: Frame afternoon discussion workshop is tasked with “what kind of beamlines”

and science case

Revolutionary of evolutionary?Extrapolation of techniques?

What will be new?

Totally new techniques?

Are we going to just move “stuff/beamlines”?We should prevent that!


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How much better? NSLS-II is not an FEL, ERL


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Soft matter

Consists mostly of C, N, and O250-600 eV covers C, N, and O edge

> 2 orders of magnitude improvement in brightness> 1 order of magnitude improvement in S/N♦

Low signal experiments> 2 order of magnitude in acquisition speed


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Opportunities: Parameter Space

Spatial resolutionSmall, with large dynamic range generally best

Spectral resolution, specific interactionsComposition, labeling

Time resolutionDynamic phenomena

Sample environmentX-ray cross sections?

Polarization control

Combination of the above!


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Opportunities: Science

MembranesWater purificationFuel cellBiology: rafts

“Shampoo” and other complex matter (Helmut Frey)

Organic devicesOLEDsPVs


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Length scales probed by some “conventional” tools

RSoXS - complement to SANS, conventional SAXS Real space info would be best, but

Contrast? Spatial resolution? Damage limits?♦

TEM needs staining♦

NEXAFS in STXM and PEEM limited to ~40 nm spatial resolution

♦

In-situ environments?

1992

H. Ade et al., Science 258, 972 (1992)

Example: Neutron-scattering at IPNS, ANL…peptides (cylinders) inserting themselves in holes they form in a cell membrane.

But:…, the best way to see part of a biomolecule

is by replacing hydrogens

with deuterium.http://www.sns.gov/aboutsns/importance.htm NEXAFS microscopy

10-11 m 10-7 m10-9 m 10-5 m 10-3 m

nano-structurecrystallography structure

atomic structure

protein

polymers

micelle

bacteria

porous media

precipitates

DIFFRACTIONX-rays, n, e- SAXS, SANS

USAXS, USANS

Light scattering

TEM

Optical microscopy

10-11 m 10-7 m10-9 m 10-5 m 10-3 m

nano-structurecrystallography structure

atomic structure

protein

polymers

micelle

bacteria

porous media

precipitates

DIFFRACTIONX-rays, n, e- SAXS, SANS

USAXS, USANS

Light scattering

TEM

Optical microscopy


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Microscopy: Morphology characterization in real space

- Contrast Mechanism- Effective “resolution”?- Quantitation?

Visible light microscopyElectron microscopyScanning probe micros.Infra RedRaman microscopyNMR microscopy

X-ray Microscopy???


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Small Angle ScatteringCoherence length larger than domains,but smaller than illuminated area

log (intensity)40

-20

-40

0

20

-40 -20 0 20 40-40

-20

0

20

40

scattering vector q (μm-1)

scat

terin

g ve

ctor

q(μ

m-1

)Structure function:

informationabout domain

statistics.

Scattering/diffraction: Structure/morphology

characterization in reciprocal space

X-rays alternative to

neutrons

Spallation Neutron Source: total cost of $1.4 billion, http://www.sns.gov/

Figure courtesy of J. Stohr

- Contrast Mechanism- Effective “resolution”?- Quantitation?


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X-ray Microscopy: X-rays have come a long way!

(Examples “biased” towards polymers/magnetic materials)

1895

1993

2003

1 μm

1992

1993 1996

NEXAFS microscopy XMCD microscopy

XLD microscopy XMLD microscopy Dynamics


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Soft X-rays

Unique interaction with matter yields unique contrast

and unique characterization capabilities


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e-

hν

C 1s edge ~ 290 eVN 1s edge ~ 405 eVO 1s edge ~ 540 eV

CH2 CH2

n[ ]

[ ]C C

n

CH2C

CH3

C

O

O

CH3

n[ ]

N

H

CC

C

C

CC N C

H

C

O

C

C

C

CC C

O

][n

Unoccupied Molecular Orbital

Near Edge X-ray Absorption Fine Structure (NEXAFS) SpectroscopyExample: “”Richness” of Polymer NEXAFS Spectra


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13Photon Energy / eV285 290

C OO

73O

C

O

27

vectra™

CH3

CH3

O CO

O n

PC

PAR

CH3

CH3

O CO C O

O

n

CCO O

NH

NH

n

Kevlar™

CCO

OO

O (CH2)4 n

PBT

PNIC

O

O

CH2 CH3

CH3

CH3

CH2 *CO

O*

n

CCO

OO

O (CH2)2 n

PET

Photon Energy / eV285 290

PS

PBrS

SAN

n

78

Br

22

n

*

C N

m

CH2 NH CO

NHNH ** n

MDI polyurea

CH2 NH CO

ONHCO

OCH2 4* *n

MDI polyurethane

CH3

N

HN

H

C

O

n

TDI polyurea

CH3

NH

NH

CO

OC

O*

O

(CH2)4 *n

TDI polyurethane

Photon Energy / eV285 290

CH2 CC

CH3

OO

CH3(CH2)3

n PBMA

CH2 CC

CH3

OO

CH3

n PMMA

* NH

C *

O

n

On PEO

Nylon-6

EPRCH3

* n

PP *CH3

n

PE * n

Fingerpt.ppt 8 May 1998

Spectroscopy = high resolution Dhez, Ade, and UrquhartJ. Electron Spectrosc. 128, 85 (2003)

Data: Stony Brook STXM at NSLS


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Types of X- ray

Microscopes

Sample

MagnifiedImage

X-ray Beam

Objective LensProjective Lens

Screen

MCP

Aperture

X-Photoemission Electron Microscope

PEEM

ALS 5.3.2 and 11.0.2 STXM

TXM

Also: Scanning Photoemission X-ray Microscope (SPEM) Ade et al. Appl. Phys. Lett. 56, 1841 (1990)

Best for NEXAFSRelatively slow

FastLimited NEXAFS


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15 C. R. McNeill et al. Macromolecues 40, 3263 (2007)

poly(9,9´-dioctylfluorene-co-bis-N,N´-

(4,butylphenyl)-bis-N,N´-phenyl-1,4-phenylene-

diamine) (PFB) and poly(9,9΄-dioctylfluorene-co-

benzothiadiazole) (F8BT)

solar cells

280 285 290 295 300 305 310 315 3200.0

2.0x104

4.0x104

6.0x104

8.0x104

1.0x105

1.2x105

F8BT PFB

Mas

s A

bsor

ptio

n C

o-ef

ficie

nt (

cm2/g

)

Energy (eV)

283 284 285 286 287

F8BT

NS

N

N N n

PFB

n

0 nm

15 nm

60

100

1:5 PFB:F8BTwt.%0

50

wt.%1 μm

0 nm

50 nm

0 wt.%

100

0 nm

50 nm

5:1 PFB:F8BT

0

50

wt.%50

90

wt.%1 μm

ihg

fed

1 μm

F8BT % composition PFB % composition Height

a cb

1:1 PFB:F8BT0

wt.%

100

Figure courtesy C. McNeill


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“Parameter space” for real space microscopy: Higher brightness, more intensity

SoXBIC would clearly benefitDamage threshold?

Surface (SPEM, PEEM) microscopy would benefitDamage threshold?

Traditional NEXAFS microscopyTransmission: Relatively little benefit from NSLS-II undulator♦

Unless some form of time resolution is achieved ♦

Would need better detectors and scanning stages♦

Great workhorse on bending magnet beamlineSecondary yield mode♦

Clear benefit, but technological hurdles♦

Damage threshold for soft matter?


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Resonant Scattering/Reflectivity

Contrast: Carbon edge examples

280 290 3000.000

0.001

0.002

0.003

0.004

0.005

β

E (eV)

PS PMMA P2VP

270 280 290 300 310

-0.003

-0.002

-0.001

0.000

0.001

0.002

δ

E (eV)

PS PMMA P2VP

Scattering factors f’

and f”

(optical const. δ

and β, respectively) show strong energy dependence

“Bond specific”

scattering!Substantial potential as complementary tool!

NP2VPPS PMMA

R or I ∝

(Δδ2+Δβ2)

Absorption (NEXAFS)

Dispersion

270 280 290 300 310 320

1x10-6

2x10-6

3x10-6

4x10-6

5x10-6

Energy (eV)

PS-PMMA Interface PS-Vacuum Interface

(c)

Ref

lect

ivity


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270 eV

Si

PMMA

Momentum transfer:

if kkqrrr

−=λαπ i

zq sin4=

Reflectivity: Tuturial-1


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100 nm PMMA 270 eV


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21 Data: Araki, BL6.3.2. ALS, Berkeley

NC STATE

University Ade Research Group (Polymer Physics/XAde Research Group (Polymer Physics/X--ray Characterization Techniques)ray Characterization Techniques)

Complementary Tool to Neutrons and hard X-

rays

Soft X-ray Resonant Reflectivity PS/PMMA bilayer

Potential: Diffuse scattering from interfaces

Observed strong photon energy dependence

0.0 0.5 1.0 1.5 2.0

Fit Data

14.2 KeV

PS(15nm)/PMMA(42nm)

320 eV

288.5 eV

285.2 eV

283.4 eV280 eV270 eV

10-12

10-9

10-6

10-3

0

Ref

lect

ance

q (nm-1)

PS

Si

PMMA

air

270 280 290 300 310 320

1E-6

2E-6

3E-6

4E-6

5E-6 PS-PMMA Interface PS-Vacuum Interface

(c)

Ref

lect

ivity

(dδ2+dβ2)/4

C. Wang, T. Araki, H. AdeAppl. Phys. Lett. 87, 214109 (2005)


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PS 50nm/PMMA 200nmReflectivity: Tuturial-2

PS

Si

PMMA

air


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Interpretation of Reflectivity Data

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

1E-4

1E-3

0.01

0.1

1

Ref

lect

ance

q (nm -1)

PS/PM M A 50 nm /200 nm 270 eV

PS

Si

PMMA

Phenomenon Physics behind it

High frequency fringes Total film thickness, sensitivity to the surface

Damping of the amplitude Surface roughness

Low frequency beating Sensitivity to the interface

Damping of the beating Interfacial roughness

Momentum transfer:if kkqrrr

−=

λαπ i

zq sin4=


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MEH-PPV is a neutral conjugated polymer spun-cast from non-polar solvent

PFNBr is a charged conjugated polymer (conjugated polyelectrolyte) spun-cast from polar solvent

interface influence?little is known about the interfacial structure and how it affects properties of such devices

C.Wang, B. Watts, T. Araki, H. Ade (NCSU) A. Hexemer, A. Garcia, T.- Q. Nguyen, G. C. Bazan, K.E. Sohn, and E.J. Kramer (UCSB).

N+ N+

n

Br- Br-MEH-PPV PFNBr

Polymer LED interfaces poly[2-methoxy-5-(2'-ethylhexyloxy)-p-

phenylene vinylene] (MEH-PPV) and

poly[9,9-bis(6’-N,N,N,-

trimethylammoniumhexyl)fluorene-co-

alt-1,4 phenylene

bromide] (PFNBr)


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Multilayer Device

270 eV

~80 nm MEH-PPV

20 nm PFNBr

~ 30 nm PEDOT:PSS

~ 30 nm ITO

Glass

Sample A. Garcia, T.-Q. Nguyen, G. C. Bazan, K.E. Sohn, and E.J. Kramer (UCSB).


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Multilayer Device

~80 nm MEH-PPV

~20 nm PFNBr

~ 50 nm PEDOT:PSS

~ 30 nm ITO

Glass


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-500x10-6

-400

-300

-200

-100

0

100

Re

flect

ance

*q4

1.21.00.80.60.40.20.0q (nm

-1)

284.6 eV

285.2 eV

285.4 eV

284.8 eV

data fit

σVacuum/PFNBr=0.9 nmσPFNBr/MEHPPV=1.1 nmσMEHPPV/PEDOT:PSS=3.5 nm

d=23.8 nm

d=75.8 nm

Sample A. Garcia, T.-Q. Nguyen, G. C. Bazan, K.E. Sohn, and E.J. Kramer (UCSB).


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Other organic electronic materials

F8BT P3HT PCBM PFB


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Resonant Soft X-ray Scattering (hard x-rays terminology ASAXS)


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Resonant Scattering: Low Contrast Example -

Developmental Porous SiLK* Resins

G. Mitchell, Dow Chemical

Decreasing feature size in integrated circuits require lower dielectric constants for insulating layers to:

increase circuit speed, decrease power consumption, decrease crosstalk

Adding pores to SiLK dielectric resin is used to decrease dielectric constant from 2.65 to 2.1 and lessFuture materials require more and smaller pores

* SiLK

is a trademark of The Dow Chemical Company

G. E. Mitchell et al., Appl. Phys. Lett. 89, 044101 (2006)


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Systematic variation in porogen size

Smallest pores collapse

Still issues with background, need to improve instrumentationWouldn’t be able to do the experiment with STXM, TEM, or SAXS. - Deuteration and SANS would work.

G. E. Mitchell et al., Appl. Phys. Lett. 89, 044101 (2006)


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Scat

terin

g In

tens

ity [a

.u]

q (1/nm)

PMMA/P(BA-co-S)

Idealized, “consensus” particle

“PS”“PS”

“PS”-”shell”

J.M. Stubbs, D.C. Sundberg Polymer 46 (2005) 1125

P(MA-b-MMA) / PS

Fuzzy TEMmodified core/shell structure?Phase less separated?Where really is the PS?

“PS”

effective radius larger than PMMA “radius”

“PS”

about same size than PMMA/acrylate!Scattering indicates PS is slightly more in center of nanoparticle relative to PMMA/P(BA-co-S)

Different process and composition

T. Araki et al. Appl. Phys. Lett. 89, 124106 (2006

(Figure courtesy J. Stubbs UNH)

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University Ade Research Group (Polymer Physics/XAde Research Group (Polymer Physics/X--ray Characterization Techniques)ray Characterization Techniques)

10-1

100

101

102

103

0.120.080.040.00

200 nm

150 nm

100 nm

280.0 eV285.2 eV288.4 eV320.0 eV

10-1

100

101

102

103

0.120.080.040.00

qR=4.5q=0.39

qR=7.73q=0.68

qR=10.9q=0.95

R=115 nm

q (1/nm)

Scat

terin

g In

tens

ity [a

.u] 280.0 eV

285.2 eV288.4 eV320.0 eV


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0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.71E-3

0.01

0.1

1

10

100

1000

10000

284.75 eV as cast 120oC for 10 min 180oC for 10 min 200oC for 10 min

I/Bea

mcu

rren

t

q(nm-1)

#0: As spun

200 deg C annealed

All polymer Solar Cell: PFB:F8BT cast from chloroform

Scale bar: 200nm

STXM

RSoXS

S. Swaratj, B. Watts, H. Ade, C. McNeill


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All polymer Solar Cell: PFB:F8BT cast from chloroform

RSoXS

278 280 282 284 286 288 290 292 294 296 298 300 302

0.0

8.0x10-3

1.6x10-2

284.8 eV #6

I/Io

Photon energy [eV]

Energy scans: 1deg off-axis

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.71E-3

0.01

0.1

1

10

100

1000

10000

284.75 eV as cast 120oC for 10 min 180oC for 10 min 200oC for 10 min

I/Bea

mcu

rren

t

q(nm-1)

S. Swaratj, B. Watts, H. Ade, C. McNeill


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GoalUse model systems (with two or three components) to establish utility and applicability of GIRSoXSCan sensitivity of each component can be tuned by tuning photon energy?

ExperimentDiblock and triblock copolymer thin films were prepared by S-J.Park, C. TangGIRSoXS experiment was carried at BL5-2 SSRL by C. Wang, B. Watts, T. Araki and B. Schlotter.9 degree incident angle, i..e above critical angle - Not true GIRSoXS.

Brief SummaryBasic quality of GIRSoXS data looks promising, but the instrument needs to be further optimizedContrast variations and scattering intensity changes as a function of photon energy have been observedFuture experiments with three-component-systems with a photon energy dependent structure factor should be explored

Resonant GISAXS on block copolymersC. Wang, T. Araki, B. Watts, H. Ade (NCSU), A. Hexemer (LBNL)

S-J. Park, T.P. Russell (UMass), B.Schlotter (SSRL) C.Tang, E.J.Kramer (UCSB)


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qy

qz

qx

Sample

CCD

CCD area 1300 x 1340, 20 μm/pixel

CCD -

Sample ~ 43 mm

Incident Angle ~ 9 deg (above critical angle)

Beam stop 15 um wire with a 200 um diameter epoxy bead. About 1 cm from the CCD

Aperture (75 x 125 μm)

Beam size: ~400 μm x ~100 μm (H x V)

X-ray

Experimental Setup•Chamber is not optimized for the reflection geometry

•The CCD angle is approx. perpendicular to the specular reflected beam.

• The Sample-CCD distance and incidence angle are estimates


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Use NSLS-II for improved energy resolution?

NEXAFS already limited by core-hole lifetimeResonant Inelastic X-ray Scattering for improved spectroscopy

But, damage!Need to back off on spatial resolution

Photon Energy (eV)

280 285 290 295 300 305 310 315 320

Opt

ical

Den

sity

0

1

2

3

4

5

6

7

Kevlar®

149

Kevlar®

49

N N C C

OO

HH][

n

Spectra with horizontal polarization in locations indicated

-30°

38°

8°

Determine degree of orientational

order


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Radiation DamageTypical critical dose ~ 1000 eV/nm3

Rose criterion for detection: S/N=5Transmission, S=-ln(I/I0)(10 nm)3 PS feature has S/N of 5 for 650 incident photons, and 115 absorbed photons in pi* peak at 285 eV

Dose= ~32 eV/nm3

Quantitation/spectra/tomography typically require 100x dose

Near critical at 10 nm for PSDose ∝ 1/(Δα)

Imaging using phase contrastScattering using phase and absorption contrast

T. Coffey et al. J. Electron Spectroscopy 122 (2002) 65 –78


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39 Data: Beamline 6.3.2 ALS

What about a “cross-over”?

I ∝ Δδ2 + Δβ2Works with low contrast

Q-range ~ 3 nm-1 (@300 eV)Dose is distributed!!Time resolution could be quite good“RSoXS” not intrinsically a brightness driven experiment

Combine low resolution STXM and RSoXS: Microbeam resonant scattering

Damage?


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Incoherent vs. Coherent X-Ray ScatteringSmall Angle ScatteringCoherence length larger than domains,but smaller than illuminated area

SpeckleCoherence lengthlarger than illuminated area

log (intensity)40

-20

-40

0

20

-40 -20 0 20 40-40

-20

0

20

40


scat

terin

g ve

ctor

q(μ

m-1

)

log (intensity)40

-20

-40

0

20

-40 -20 0 20 40-40

-20

0

20

40


scat

terin

g ve

ctor

q(μ

m-1

)

informatio n

about domainstatistics

trueinformatio

nabout

domainstructureFigure courtesy J. Stohr

Resonant scattering and resonant speckle should be excellent tools for organic materials !!!!


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Other possibilities

Resonant x-ray photon correlation spectroscopy?R-XPCS

Resonant coherent imaging?Coherent imaging proposed by other workshop!

Spatially resolved inelastic scattering?Damage?Sensible domain size?


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Conclusions

NEXAFS microscopy and resonant reciprocal space techniques are excellent “compositional” tools with 1D, 2D, and 3D (tomography) spatial resolution well below 1 micron.C,N, O edges have feature-rich spectroscopy for organic materials.

SpecificityMany organic, soft condensed matter application will continue to benefit from these toolsThin samples 100-2000 nm thick.

Science opportunitiesSee Helmut Frey


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If we were a rich man?

Bending magnet STXM workhorseBending magnet RSoXR/RSoXR workhorse

Microfocus RSoXS undulator beamlineIntensity at sample scales with brightness/coherenceSoft x-ray EPU beamline

R-XCPSNeeds coherenceSoft x-ray EPU beamline

……..

Beamline design(s) most likely relatively conventional (except heatload). Most advances are in the endstations


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Thank you for your attention!!!!

Thanks to members of my group: B. Watts, S. Swaratj, T. Araki, and C. Wang

and

Bill Slotter, Jan Luning

(Stanford). C. McNeill (Cambridge), A. Hexemer

(ALS), A. Garcia, T.-Q. Nguyen,

G. C. Bazan, K.E. Sohn, and E.J. Kramer (UCSB).

Documents

in real and reciprocal space? - Brookhaven National Laboratory · in real and reciprocal space? NSLS-II Workshop February 11, ... NSLS-II_ade_Feb_2008.ppt NC STATE University 11