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

10B/2003G266

Development and evaluation of uncertainty of precise quantitative analysis by
XAS for a primary standard
Nobuyuki MATSUBAYASHI*1, Motoyasu IMAMURA1
1AIST, Tsukuba, Ibaraki 305-8565, Japan
0.00060.00040.000200Experimental
XAFS spectra of Zr K-edge (18 keV), Mo K-edge (20keV), and Sn K-edge (29 keV) of standard solution intransmission mode were measured at BL-10B using
precise quartz cells with 1, 2, 4 , 5 cm thickness which arecalibrated by the three-dimensional measurement system(Carl Zeiss UMM550) traceable to national standard of
Iodine-stabilized He-Ne laser (NMIJ). The error wasbelow 3 µm in 4 points on optical windows at 293 K.

46

Users' Report

100Collection Time (min)200

Fig.1 Effect of collection time on standard
deviation(σ) for Mo solution of various
concentration.

1.5

1C∆µResusts and Discussion
Though the shape of the absorption edge just above thethreshold depend on element, oxidation state andcoordination structure, we have developed analysis
algorithm to remove structure of XANES and EXAFSautomatically without arbitrariness. An absorption edge
jump of excitation cross section of a specific core electronof an isolation atom that removed structure by thismethod is in proportion to the number of atom on opticalpath, and an absorption edge jump per optical path length3
1 m of the density of element 1 mol/m is defined as mol
2
absorption edge jump coefficient, C∆µ (m /mol), relationof ∆µ=C∆µ C L, where ∆µ is absorption edge jump, C ismol density (mol/m3), L is optical path length (m).
Figure 1 shows effect of collection time on standard
deviation(s) for edge jump (∆µ) of Mo in solutions ofvarious concentration by 4 cm-cell. Each scan was takenby 10 min. Each numbers of sample data was 12, 38, 45,
for 990, 99, 9.9 ppm, respectively. Each average of ∆µwas 0.291, 0.0286, 0.0023 for 990, 99, 9.9 ppm,respectively. These results suggest that it is possible evenfor lower concentration than 10 ppm by long collection
time. A dispersion of data every scan (standard deviation)
decreases by increasing collection time.
Figure 2 shows coefficient parameter of absorption
edge jump (C∆µ) vs. atomic number obtained bymeasurements of some standard solutions using 2 cm cell.

9.9ppm (45)99ppm (38)990ppm (12)σIntroduction
All data of measurement and analytical technique
should be evaluated with internationally approved
reference and traceable to the SI.
X-ray absorption by an absorption edge follows
Lambert-Beer law so can be primary standard if thecoefficient is exactly determined. The technical problem
is determination of the edge jump without affection ofstate of absorbing atom. We have developed the method
to determine the edge jump automatically by modifying amethod for EXAFS analysis.

0.50304050
Atomic Number

60Fig.2 Coefficient parameter of absorption edge
jump vs atomic number.
The results indicate that the coefficient parameter (C∆µ)
can be expressed first order exponential function of
atomic number (Z). The result of a least square fitting
wasC∆µ =exp(1.894-0.05345xZ)
This indicates that we can estimate a value byinterpolation and extrapolation on the element that astandard sample is not provided.
We will extend the measurements to determine the C∆µof other period elements and L absorption edges.

*n-matsubayashi@aist.go.jp