Photon Factory Activity Report 2005 #23 Part B (2006)
Chemistry

9C, 10B, 12C, 14A/2005G241

Study on Quantitative Analysis Technique for thin films using XAS
Nobuyuki MATSUBAYASHI*, Motoyasu IMAMURA, Jiangwei FAN, and Isao KOJIMANMIJ/AIST, Tsukuba, Ibaraki 305-8565, Japan

Resusts and Discussion
An absorption edge jump of excitation cross section ofa specific core electron of an isolation atom is inproportion to the number of atom on optical path. The
absorption edge jump per an unit of optical density ofelement (1 g/cm2 ) is defined as absorption edge jump
2coefficient, C∆µ (cm /g), relation of ∆µ=C∆µD, where∆µ is a quantity of the absorption edge jump of the2element, D is the optical density of the element (g/cm ).
Figure 1 shows the C∆µ vs. the atomic number (Z)obtained by measurements of some standard solutions
using 2 cm cell and calculated using Victreen formula [1]and semiempirical calculation data by Henke [2]. The
values agreed well though it was difficult to determine theedge jump because the calculated values by Henke are
discretely given on some characteristic x-ray energies.
The results indicate that the C∆µ can be expressed firstorder exponential function of the Z. The result of a leastsquare fitting wasC∆µ =exp(7.62 - 0.07916 Z).
This indicates that we can estimate a value byinterpolation and extrapolation on the element that astandard sample is not provided.
The values of C∆µ• for L-edge absorption of Pt and Au
were also determined by the same method to 125.4 and2C∆µ(cm /g)

8060Exp.
VictreenHenke40204045
Atomic Number

50Fig.1 Coefficient parameter of absorption
edge jump vs atomic number.

0.002
5µm Pt foil
5nm Pt/SiO2

10.0010.5011500

12500
12000
E/eV

ABSORBANCE(log(I0/I)) for 5nm Pt/SiO2Experimental
XAFS spectra of K-edge for an elemental series fromthSr(38) to Sb(51) of the 5 periodic table and L3-edge forPt and Au in standard solutions (1000 ppm standards for
Atomic Absorption Spectrometry by Wako Pure ChemicalIndustries, Ltd.) in transmission mode were measured atPhoton Factory using precise quartz cells with 0.5, 1 and
2 cm thickness which are certified by Japan Quality
Assurance Organization using the three-dimensional
measurement system (Carl Zeiss UMM550) traceable tonational standard of Iodine-stabilized He-Ne laser (NMIJ).
The error was below 3 µm in 4 points on optical windows
at 293 K.

100

ABSORBANCE(log(I0/I)) for 5µm Pt foil

Introduction
A quantity of x-ray absorption by an absorption edge
follows Lambert-Beer law so it can be a method forquantitative analysis of an element in various materials
without destruction if the coefficient is exactlydetermined. The determination of the edge jump without
affection of state of absorbing atom is one of the technicalproblems. We have developed the method to determine
the edge jump automatically by modifying a method forXAFS analysis. Furthermore the XAFS gives informationof the chemical state and local stricture of the element.

013000

Fig 2. XAS of 5µm Pt foil and 5nm Pt/SiO2.
119.8 cm /g, respectively. Figure 2 shows XAS of a 5 µmPt foil and a Pt evaporated film to be 5 nm thickness on
SiO2 obtained by transmission mode at 9C (the collectiontime was 35 min and 120 min, respectively, under a single2bunch mode) resulting as D, 129.8 and 0.1266 g/cm ,respectively. It indicates that quantitative analysis by XAS
can be applicable to ultra thin films in a nm-scale.
2References[1] The International Tables for X-ray Crystallography 2,157(1972) .
[2] B.L.Henke et al. , Atomic Data and Nuclear Data
Tables, 54, 181(1993).
*n-matsubayashi@aist.go.jp

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