SPring-8, the large synchrotron radiation facility

Inquiry number

SOL-0000001069

Beamline

BL01B1 (XAFS I)

Scientific keywords

A. Sample category	inorganic material, biology, medicine
B. Sample category (detail)	solution, environmental material
C. Technique	absorption and its secondary process
D. Technique (detail)	XAFS, XANES
E. Particular condition	polarization (linear), time-resolved (slow), room temperature
F. Photon energy	X-ray (4-40 keV)
G. Target information	chemical state, trace element

Industrial keywords

level 1---Application area	environment, others
level 2---Target	catalysis, Environmental material
level 3---Target (detail)	ash
level 4---Obtainable information	valence, chemical state
level 5---Technique	XAFS, NEXAFS

Classification

A80.40 environmental materials, M40.10 XAFS

Body text

In this solution, in-situ fluorescence XANES method at Se K-edge was applied to study change in chemical state of dilute Se (83 ppm concentration) in aquatic sediment by bacteria. For dilute aquatic samples, the fluorescence XANES method is a powerful technique to study local electronic structure (valence, species of neighbor atoms) and chemical composition of selected elements. Pattern fitting analysis of the XANES spectra (Fig. 1) using reference samples revealed that toxic Se (VI) is reduced to Se (0) through Se (IV) by bacteria treatment (Fig. 2).

Fig.1 Se K-edge XANES spectra. Each broken line shows peak energy of Se (0), Se (IV) and Se (VI), respectively.

Fig.2 Time course of chemical composition of Se by bacteria treatment.

Source of the figure

Bulletin from SPring-8

Bulletin title

SPring-8 Research Frontiers 2003

Page

97, 98

Technique

XAFS spectra of dilute samples are taken by fluorescence XAFS method. This method is performed by measuring fluorescence from excited atoms as a function of x-ray energy around an absorption edge of a selected element. A 19-element Ge detector is used for measurement of 1-1000 ppm samples. Acquisition time per XANES spectrum is 15-30 min in this solution.

Source of the figure

No figure

Required time for experimental setup

4 hour(s)

Instruments

Instrument	Purpose	Performance
XAFS Measurement System	Measurement of XAFS spectra	3.8-113 keV
19 Ge Detector	Measurement of XAFS spectra of dilute sample and thin film	concentration: 1-1000　ppm, thickness > 0.1 nm

References

Document name
S. Fujiwara et al., SPring-8 Research Frontiers 2003, (2003) 97

Related experimental techniques

Questionnaire

This solution is an application of a main instrument of the beamline.
With user's own instruments.

Ease of measurement

Middle

Ease of analysis

Easy

How many shifts were needed for taking whole data in the figure?

Two-three shifts