Photon Factory Activity Report 2004 #22 Part B (2005)
Materials Science

10C, 2004G066

Study on Nano-Structure Formation of Organic Metal polymer
by Small-Angle X-ray Scattering utilized with Anomalous X-ray dispersion Effect3
Masaaki SUGIYAMA*1, Yuji SOEJIMA 2, Kazuhiro HARA
, Keiji ITOH1, Kazuhiro MORI1,
1
Toshiharu FUKUNAGA
1
Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494, Japan
2
Research and Development Center for Higher Education, Kyushu University, Ropponmatsu,Fukuoka 810-8560, Japan
3
Institute of Environmental Systems, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan

Experimental
Dodecyl-ferrocenecarboxylic potassium (DFCP) wasused for the sample with an anomalous atom, Fe. DFCP
makes microphase separation between domains of alkyl
chains and carboxylic potassium. The phase-separated
structure is one-dimensional periodic one, lamella. It
means that Fe atoms also periodically locate in the sample.
One of the features of A synchrotron light (SL) is Xray source with wide wavelength range. Therefore, SL isa suitable X-ray source of our SAXS method with energy
sweep. The SAXS measurements sweeping the energyaround the Fe-K absorption edge were performed at
BL10C of Photon Factory, synchrotron light facility inHigh Energy Accelerator Research Organization (KEK),Tsukuba Japan. The SAXS intensities were measured in
the sweep range of X-ray energy between 7.09-7.13 keVwith an energy step of 20 eV. The energy of the incident
X-ray was tuned with double monochromatores of Si witha resolution δE/E=10-4. The scattered X-ray was detectedwith a one-dimensional detector and the intensity wasaccumulated for 600 sec at each energy scanning step: thecorrections were made for absorption by the specimen
and for the decay of the orbit current of the synchrotron.
Results and discussion

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Users' Report

In most of the SAXS profiles of DFCP, a peak was
observed around 2.0×10-1 Å-1, indicating that there exists
a periodic structure with an interval of 31.9 Å. This value
shows a good agreement with the published datum. The
lamellar structure could be formed by the microphaseseparation between alkyl chains and carboxylic acid.
Therefore, Fe atoms in ferrocene molecules also locate
periodically with the same interval of the lamella.
Figure 1 shows the energy dependence of peak profiles
by energy-sweep SAXS experiments. As you can see, thepeak almost disappears at the Fe-K absorption edge (7.11keV). It means that a negative anomalous atomic form
factor f’ does not ignore at the absorption edge. This
result also indicates that we can control the contrast ofsample for X-ray by sweeping the energy of an incident
X-ray.

6

Intensity / a.u.

Introduction
It is well-known that small-angle X-ray scattering(SAXS) is one of powerful tools to investigate structureswith nano scale. The SAXS observes a spatial fluctuationof electron density of a sample. There are two kinds ofthe fluctuations: one is a density fluctuation and the otheris a heterogeneous distribution of the atoms and/or
molecules. However, it is difficult to distinguish between
two electron density fluctuations only with a standard
SAXS method. Therefore, our purpose is to find out amethod to be able to distinguish these two fluctuations.
Here, we focus attaint ion on X-ray anomalous dispersion
effect to solve this problem: The anomalous atomchanges its atomic form factor around the absorption edge.
Using this feature, we could derive a distribution of
anomalous atoms from the fluctuation of the electron
density distribution, which is observed with the standard
SAXS method. Along this line, we have made an attempt
to utilize the X-ray anomalous dispersion effect in SAXS
method by sweeping the incident X-ray energy around theabsorption edge of the anomalous atom.

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0.18

0.19

0.20

0.21

Scattering vector / Å0.22-1

Figure 1. Energy dependence of of SAXS peak
profiles of DFCP around the Fe-K absorption edge
(7.1109 keV). The thick, thin and dot lines indicate
the profiles of peaks observed with incident X-ray
energies of 7.09, 7.11 and 7.13 keV, respectively.
*sugiyama@rri.kyoto-u.ac.jp