Small-angle scattering technique : From X-rays to
neutrons to lightShahidan Radiman
School of Applied Physics , Faculty of Science and TechnologyUKM Bangi 43600 , Selangor DE.E-mail: [email protected]
www.ukm.my/fst
UPNM Invited Talk 16 June 2015
The First British Neutron Summer School at Rutherford Appleton Lab , 1986
Arrow – me excited in this 2 weeks Summer School staying at St Annes College, Oxford University (nearby)
Content of Talk•1. Overview of Small-angle Scattering Technique (some from Eric Kaler’s slide)•2. Methods of Analysis•3. Some applications•4. Conclusions
1.Overview of Small Angle Scattering Techniques
(SANS , SAXS, SALS)
Small-angle scattering techniques:
Neutron scattering length density differences
SANS Basic Concepts
At large q:
S/V = specific surface are
10 % black90 % white
)()()( 2 QSQPVQdd
pcoh
Δθ
Sizes of interest = “large scale structures” = 1 – 300 nm or more
SANS Approach QS
ki
kS
SSD SDD≈
S1 ≈ 2 S2
Optimized for ~ ½ - ¾ inch diameter sample
2 θ
S1
3m – 16m 1m – 15m
An early application of our UKM SAXS facility –elucidating LLC structures !
2. Methods of Analysis
F = 10-13 cm
3. Some Applications
4. Conclusions
1.SAXS, SANS and SALS are complementary techniques – they cover different q-ranges but also they “see” different parts of the molecules/ nanoparticles2.Ultra small-angle techniques (X-rays and neutrons) makes light scattering technique obsolete3.SANS are preferable where contrast variation can be made (mainly biological samples) and where not too high resolution is needed.4.SAXS are prefered when high resolution (higher ordered peaks) are needed not only for weakly scattering species but also for “finger- print “ purposes ( many types of proteins)- here the role of synchrotron source (typical intensities a million x more than lab sources) becomes important !
5. Small-angle scattering techniques are model-dependent , so that complementary methods must be used hand-in-hand with this techniques for conclusive determinations.
6. For biological samples (Malaysia is mega -biodiversity country) there is already a bank for small-angle scattering samples , see : www.sasbdb.org
In this groundbreaking paper, we showed for the first time the existence of triply-periodic minimal surface of the cubic type occuring in a lyotropic liquid crystal system which is ONLY possible using contrast variation technique on SANS
Sophisticated Bayesian Error Analysis are also currently available
Facilities in the SEA Region
1.Synchrotron source (Small-angle Xray scattering) : SIAM Photon Source, Thailand (Dr. Supagorn Rugmai)2.Ultra Small-angle Neutron Scattering and Small-angle Neutron Scattering Facility , BATAN –Serpong, Indonesia ( Dr. Edy Giri Putra Rachman)3.SANS Facility at Malaysia Nuclear Agency ( Dr. Mohd Rawi )4.SAXS facilities around the country – UKM ( Prof. Shahidan Radiman), UM ( Prof. Rauzah Hashim) , MIMOS ( ?)
Further development of neutron instrumentation at the Triga Mark II Reactor will need simulation support (SIMRES) for optimisation and instrumentation component selections.
Photo: Prof. Dr. Jan Saroun, Nuclear Physics Inst. , Czech Academy of Science, giving workshop on SIMRES at the Malaysian Nuclear Agency (2 -5 , June 2015).
Most recent review paper on Small Angle X-ray Scattering technique- its still popular !
Thank you very muchfor your attention !ال�ـصـواب� ع�لُم ب�� وال�له ا�
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