Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron...

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Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson, Jacob Tarver

Transcript of Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron...

Page 1: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Microemulsion Dynamics fromNeutron Spin Echo

Spectroscopy

Group DNCNR Summer School

2007

Sheila Khodadadi, Maggie Johnson, Jacob Tarver

Page 2: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Why study microemulsions?

1987 J. Huang et alPRL 59

Role of interfacetension vs bendingenergy

Fluctuations drivenby bending elasticity

2nm

Page 3: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

How do we measure the dynamics?

0.05-15ns

SANS Structure Factor

Radius ~30A

Coherent scattering-collectivedynamics of surfactant shell

Contrast Match SLDs

solvents(D20, d-hexane)~6.1E-6

Surfactant (AOT) ~0.7E-6

Page 4: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

NSE Spectrometer

Scatters from the nuclear interactionMeasured property-Final polarization

!

"# $%tF

!

tF"#3I

I is field Integral

Page 5: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Elastic Scatter

Page 6: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Data - Intensity for 1 detector

!

PZ =2A

Nup " Ndown

A

Also normalize to Carbon powder (Resolution)

Page 7: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Results on microemulsion

I(Q,t) atQ=.065,0.1,0.125

13 fourier times atλ=6A

!

I(Q,t)

I(Q,0)= exp "Deff (Q)Q

2t( )

Page 8: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Results-Elastic modulus

Q

Def

f

!

Deff (Q) = Dtr (Q) + Ddef (Q)

Extract Fit parameters R0, a2, Dtr,λ2

k=0.25kT

Page 9: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Conclusions

Were able to measure dynamics andelastic modulus for surfactant shell

Subsequent experiments have used spin-echo to study elastic modulus ofmembranes. (Bossev 2005 SS Invited Talk)

Page 10: Microemulsion Dynamics from Neutron Spin Echo Spectroscopy · Microemulsion Dynamics from Neutron Spin Echo Spectroscopy Group D NCNR Summer School 2007 Sheila Khodadadi, Maggie Johnson,

Acknowledgments

Antonio Faraone, Yamali HernandezMichihiro Nagao , Jason Gardner, Maikel

RheinstadterSummer School Instructors & PresentersJulie KeyserDAVE software http://www.ncnr.nist.gov/dave/download.hmtl

CHRNSTHANKS!