SANS at ISISRichard Heenan – ISIS Facility. r.k.heenan@rl.ac.uk

DIAMONDLight Source

ISIS TS-1

ISIS TS-2

ISIS 800Mev Proton accelerator

Rutherford-Appleton Laboratory & Harwell Science and Innovation Campus

New Logo April 2007

ISIS second target station, takes 1 in 5 pulses at 10Hz from 300μA synchrotron (currently being upgraded from 200μA).

First phase - 7 beam linesautumn 2008. Includes new SANS instrument with 20-30 times neutrons!

Neutron generation at ISIS800 MeV protons, pulsed 50Hz, mean 200 µA, 160 kW on tungsten target,produce ~2×1016 neutrons/sec from spallation

70 MeVH-

800 MeV H+

~90% light speedneutrons

muons

30 Instruments at ISIS - end 2008

4 of 5 at 50Hz

StructuresNIMROD Intermediate

range order in liquidsWISH High-resolution

magnetic structureSANS2D Large molecule

structure in multi-component systems

ISIS TS-2 Phase One Instruments

ReflectometryINTER Air/ liquid/ solid interface interactionsOFFSPEC Structures of membrane, protein and liquid interfacesPOLREF Interface measurements in magnetic sensor devices

DynamicsLET High-resolution measurement of material energy scales

1 of 5 at 50Hz = 10Hz

07/03/05

ISIS TS-2

08/09/06

07/09/06

27/07/07

27/07/07

Sample position 19m from moderator

Two 1m square detectors in a 13m long, 3.25m diameter vacuum tank.

SANS2d on ISIS TS-2

5 x 2m long removable guides in 3 ton shielding blocks

Sample position 19m from moderator

)2/sin(4 θλπ=Q

Two 1m square detectors in a 13m long, 3.25m diameter vacuum tank.

5 x 2m long removable guides in 3 ton shielding blocks

SANS2d Collimation L1 = 2 to 12 m,

Sample at 19m from moderator, Sample to detector L2 = 2 to 12 m, Qmin~ 0.002 Å-1, λ = 1.5 to 12 Å by time of flight,Qmax~ 3 Å-1

ChopperBender

Sample MovableDetectors

Removable Guides

SANS2d Progress• Bender, guides, detectors delivered.

• Rails etc in tank Oct 2007.

• Moving guide blocks being assembled.

• Some test beam in summer 2008 ?

• Extremely wide simultaneous Q range, ~ 0.002 to 3 Å-1 using λ ~ 1.5 to 12 Å, with L2 ~ 2 to 12m and two 1m square detectors.

21st March, 3.25m ID, 13m long

vacuum tank

24th Aug, concrete plinths

What SANS ( & SAXS) tells us ...

• Nanostructure (size, shape)

• Internal features (contrast variation)

• Molecular weight - aggregation number

• Surface/volume (Porod)

• Interactions (hard, soft, charged)

• Location of components (contrast variation, interfaces)

• Relation to microstructure (porous solids etc.)

Dilute particles

Concentrated systems

We always learn something ….

SANS2d - science

Overall size & shape of Tn3 resolvase (protein) – DNA complex, using neutron & X-ray contrasts plus known crystal structures.

“Small Angle Scattering” = “big”structures of colloidal droplets or particles, surfactants, polymers (plastics), biomolecules, drug delivery systems and much more !Many practical applications, on ever more complex samples.Clever sample environment, D2O/H2O contrast variation, wide range of scattering angles are key.

xy

Lipid coated DNA, delivery system.

Hierarchical structure in polymer gel.

Ordered structures in flowing surfactants

I

III

VIVIIV

f e

c

HOOC

d

a

NH2

b

I

III

VIVIIV

f e

c

HOOC

d

a

NH2

b

Surfactant stabiliseddrug targets membrane protein

SANS ( & SAXS) experiments ...

• Usually looking at systematics – change concentration, temperature, pH etc.

• Or apply stimulus such as shear, or temperature jump, or laser.

• Trend to more complex systems.

• Can use contrast variation to highlight parts. (Often just D2O/H2O or other D/H solvent mixtures.)

• Some simple examples here, without any expensive deuteration.

We always learn something ….

)sin(4 θλπ== kQ

Scattering vector, units Å-1 or nm-1,for scattering angle θ, wavelength λ

EXAMPLE: “SMALL PARTICLES” Ionic liquid dissolved in water.

Ian Goodchild, Laura Collier, Sarah L. Millar, Ivan Prokeš, Jason C.D. Lord, Craig P. Butts, James Bowers, John R.P. Webster, Richard K. Heenan, Journal of Colloid and Interface Science 307 (2007) 455–468

1-alkyl-3-methylimidazolium in D2O[Cnmim]X, where n = 2, 4, 6, 8, 10, X =Br or Cl

“cmc” is very high up to 2M, φ ~ 40%v for n = 2;at n = 8 is ~ 0.15M ~ 4%v

Systematic study of phase diagrams, NMR, surface tension, conductivity, and direct measure of bulk aggregation by SANS and surface structure by Neutron Reflection.

SANS show “micellar” type aggregates for higher n, with classic charged particle interactions.

“Head”

water

“Tail”

SANS data in D2O, with core/shell model fits:

[C10mim]Br [C8mim]Br [C6mim]Br

0.6 M

0.04 M

1.5 M

0.2 M

1.5 M

1.2 M

1.0 M

0.6 M

Nagg ~ 40, Rcore ~ 13Å, growing prolate at higher concs, cmc ~ 0.04M.

Nagg ~ 22, Rcore ~ 11Å, cmc ~0.15M

Nagg ~ 22, Rcore ~ 11Å, possibly oblate, cmc ~ 0.5M, 12%vn = 2, 4 show no SANS signal, but tensions and conductivity show cmc ~ 2.0 & 0.8 M

BKGQSQPNVQI +Δ==Σ )()()()( 22 ρ∂ω∂

Interactions – hard or charged spheres

Size & Shape

Composition

)sin(4 θλπ== kQ

EXAMPLE: “Small copolymer (or large surfactant ? ) micelles”

E18B10 poly(oxyethylene)-poly(oxybutylene) dissolved in water, E= (CH2CH2O); B = CH2CH(CH2CH3)O

J.P.A. Fairclough, A. Norman, B. Shaw, C.Booth, V.M. Nace, R.K. Heenan & S.M. King,

Polymer International 55 (2006) 793-797.

0.01

0.1

1

10

100

1000

0 0.05 0.1 0.15 0.2 0.25q/Å-1

I(q) /

cm-1

25°C

35°C45°C

65°CFit 25°C

Fit 35°CFit 45°C

Fit 65°C

(85)(71)(24)(30)65

(84)(66)(30)(29)45

6455243035

6554202925

Wshell%v

Router Å

Wcore%v

RcoreÅ

T (°C)

Constrained core/shell polydisperse spheres.Lower temps fit well and absolute scaling is good, if allow some water in core. (Possibly some E/B block disorder ?)

As temperature increases fits (brackets) are worse and parameters and absolute scaling do not make sense!

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80

Polymer fraction vs Radius T=25,35,45°C

Constrained core/shell polydisperse spheres.

0.01

0.1

1

10

100

1000

0 0.05 0.1 0.15 0.2 0.25 0.3

q/Å-1

I(q) /

cm-1

45°C

Fit 45°C

65°C

Fit 65°C

(65)26480016065

(95?)30761.545

Wshell%v

Router ÅContour length L Å

n segments

T (°C)

Worm like chain works well at 65°C, but it may be starting to phase separate, as absolute intensity is not too good and details are not quite same as similar systems in literature.

45°C may be a mixture of shapes & sizes.

Alas should have recorded some more intermediate temperatures!

Worm like chain (Kholodenko-Dirac)

A.L.Kholodenko, Macromolecules 26(1993)4179-4183

FISH programme lets you try a lot of different model types quite easily ........

R

sld

R1

ρ1

R2

ρ2

ρ3

e.g. Dilute spherical Shell R1 = 40 Å (R2-R1) = 15 Å (with 15% polydispersity)

}{ 222321121 ),()(),()()( RQFVRQFVNQI ρρρρ −+−= ( )

3)()cos()sin(3),(

QrQrQrQrrQF −=

Constrained core plus shell models

For spheres, cylinders or ellipsoids, may compute shell thickness from expected (head group)/(tail) volume ratio, also include %v of hydration water in head group.

I(Q) is integrated numerically for a Schultz distribution of particle sizes for either inner or outer radius.

Least squares fit for mean radius, polydispersity σ/Rbar, etc.

Shell interference

EXAMPLE - CONTRAST VARIATION: EC/DDAO/water - oil in water microemulsion

Core

Shell x5

Drop x25

S(Q) x10

1.4% vol, RDROP ~ 32 Å, RCORE ~ 17 Å

Simultaneous polydisperse, charged sphere, fits have ~ 29% vol ester oil in tails.

Dashed lines - no oil in tails, SSE is x5 worse

D.J.Barlow, M.J.Lawrence et.al. Langmuir 16(2000)10398-10403.

Ethyl caprlate, ester, oil, stabilised by N,N-Dimethyldodecylamine-N-oxide (LDAO).

DROP contrast – Hoil, H-DDAO, D2OSHELL contrast – Doil, H-DDAO, D2OCORE contrast – Doil, H-DDAO, H2O

“Studies on the incorporation of testosterone enanthate into microemulsion droplets stabilised by N,N-dimethyldodecylamine-N-oxide”

D J Barlow, M J Lawrence1, R Shah, T Zuberi, S Zuberi & R.K.Heenan, Submitted.

Testosterone

CONTRAST VARIATION: EC/DRUG/DDAO/water - oil in water microemulsion

Add drug to ethyl caprlate, ester, oil, stabilisedby Dodecyldimethylamineoxide (LDAO).

DROP contrast – Hoil/DRUG/H-DDAO, D2OSHELL contrast – Doil/DRUG/H-DDAO, D2OCORE contrast – Doil/DRUG/ H-DDAO, H2O

•Now a 4 component system where BOTH drug and oil can partition into the surfactant shell. Drug in first paper is TE, recent work on eutectic mixture.

•Droplets ought to be spheres, but irregular shaped drug so test prolate and oblate ellipsoids also!

•Highly constrained models fit droplet size and fractions of oil and drug in shell (with exact composition of every sample).

•Have data for low, medium, high oil with zero, low, medium, high drug ( 12 systems) x 3 contrasts each.

Testosterone enanthate

DDAO

EC

Oil

Low Drug 0.05%v, Medium Oil 0.75%v DDAO 1.75%v:Simultaneous fits. All have Poil ~ 0.7,

black lines spheres (slight preference for Pdrug towards zero), Rdrop 28.1 Å, polydisp 16%, shell 14.8 Åblue lines oblate (cannot tell Pdrug)red dash prolate (cannot tell Pdrug)

(sum of squared errors is best for spheres, then oblate x1.5, then prolate x2 worse)

Core

Shell x5

Drop x50S(Q) x100

Here can usually locate the oil, but not always the drug (need SANS2d), as droplets are small.

The trends are rather complex !

A rare case of “too much information” in SANS patterns.

Cowpea Chlorotic Mottle Virus is well studied and available in large quantities.

The goal of the Nijmegen group is to:

1. Disassemble the 280 Å diam virus.

2. Remove the interior RNA.

3. Re-assemble the protein “capsid” shell ( ~ 265 Ådiam).

4. Use the shells as a “nano-reactor” or to trap polymers.

Alas re-assembly is not perfect, the shell “degrades”, in ways that are difficult to model, and seem to vary with pH, [salt] and in some cases over time:

Example: SANS from Virus & Viral CapsidsUnpublished data and samples from Martin J.Feiterset.al. Nijmegen

CCMV 180 subunit protein cage, from Douglas et.al. Adv.Mater. 14(2002) 415-418, based on Speir et.al. Structure 3(1995)63-78.

Schematic e/m illustrations of the viral capsid in its normal (i) and swollen (ii) state and as a virus-polymer biohybridarchitecture (mega amphiphile) (iii)

+ Virus, monodisperse sphere model

Capsid :

+ pH 5, polydisperse sphere

+ pH 5 low salt, prolate shell ellipsoid

+ pH 6.5, prolate shell, oblate shell

Virus

Capsid

SANS data

• Shape change and polydisperse size distributions are being tried by RKH using FISH program.

• Want “simple”, fast method to characterise many samples.

• Other methods, such as “Debye sphere modelling” would be slow and only suit monodisperse systems (need to try some).

• Least squares fits to spherical shells with complex density profiles are however also “difficult”!

• Simultaneous fit to “whole virus” in D2O and “RNA matched” virus in 68% D2O, suggests that RNA (not seen in crystal structures due to disorder) is not uniformly distributed:

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 25 50 75 100 125 150

Radial Φ(R)

RNA

Protein

R (Å)

68% D2O, RNA matched

100% D2Owhole virus

WHOLE VIRUS – simultaneous monodisperse sphere fit.

Q (Å-1)

SANS experiments ...

• Can tell us a great deal about systems in the 10 – 1000 Å ( 1- 100 nm) size range.

• Much new investment at ISIS, particularly for soft matter & biology !

• Contrast variation is powerful. Though specific deuteration may be worthwhile, much can be done with D- and H- solvents.

• A lot of sample environment is available –cryostats, furnaces, shear & flow cells, simultaneous rheology – please ask!

• We can help with data fitting and analysis if you can do the chemistry!

THANK YOU, especially Gino, for your Hospitality !

www.isis.rl.ac.ukelectronic proposals 16 April & 16 October, discuss first with an instrument scientist. r.k.heenan@rl.ac.uk

Main Detector 65cm square at 4.1m

)2/sin(4 θλπ=Q

The neutron source is LARGE ~ 10 x 10 cm so the beam line is LONG.

Neutrons are a form of radiation, so there is a LOT of shielding to keep users safe.

Two circular apertures A1 and A2, usually 20 & 10 mm diameter, collimate the beam.

Neutrons

BenderChopper

A1 A2 High Angle Bank50cm square at 0.5m

Sample

Wax

Steel

Concrete + Steel shot

Mirror

LOQ at ISIS