JP4279983B2 - X-ray fluorescence analyzer - Google Patents
X-ray fluorescence analyzer Download PDFInfo
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- JP4279983B2 JP4279983B2 JP2000285152A JP2000285152A JP4279983B2 JP 4279983 B2 JP4279983 B2 JP 4279983B2 JP 2000285152 A JP2000285152 A JP 2000285152A JP 2000285152 A JP2000285152 A JP 2000285152A JP 4279983 B2 JP4279983 B2 JP 4279983B2
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Description
【0001】
【発明の属する技術分野】
本発明は、FP法で試料の組成を分析する蛍光X線分析装置において、X線管からの特性X線の影響を補正する装置に関するものである。
【0002】
【従来の技術】
従来より、蛍光X線分析では、試料にX線管から1次X線を照射し、発生する蛍光X線の強度を検出器等で測定して、試料の組成等を分析するが、X線管からは、ターゲット元素の特性X線の他に、X線管窓に付着した物質やX線管内の構造物の元素の特性X線、いわゆる不純線が発生する。この不純線が試料で散乱して検出器で検出されると、試料中の成分から発生した同じ波長の蛍光X線と区別がつかない。
【0003】
これに対し、例えばファンダメンタルパラメータ法すなわちFP法では、蛍光X線の測定強度に基づく理論強度スケールへの換算強度と、試料における各成分の含有率(試料の組成)を仮定して計算した蛍光X線の理論強度を対応する成分ごとに対比し、両強度が合致するように、仮定した各成分の含有率を逐次近似的に修正計算して、各成分の含有率を算出するが、前記不純線の影響を補正するため、不純線と同じ波長の蛍光X線を分析線とする成分を含まないブランク試料を用いてあらかじめ不純線の散乱強度を測定しておき、分析対象の試料における分析線の波長での測定強度から差し引いて、試料中の成分から発生した蛍光X線のみの測定強度としていた。
【0004】
【発明が解決しようとする課題】
しかし、不純線の測定強度は、試料の組成の影響を受けるため、ブランク試料と分析対象の試料との組成が大きく異なる場合には、不純線の影響を正確に補正できない。また、あらゆる品種の試料に対応すべく、膨大な数のブランク試料を準備して不純線の散乱強度を測定しておくことも、実際上きわめて困難である。同様の問題が、試料にX線管のターゲット元素が含まれる場合にも起こる。すなわち、そのような場合には、試料から発生した蛍光X線に重ならないように、X線管のターゲットからの特性X線を、1次フィルタを用いて、X線管から発生したX線から除去して1次X線とするが、完全には除去できず、上述の不純線と同様に、その影響を正確に補正できない。さらに、このようなX線管からの特性X線の影響の補正は、分析線とX線管からの特性X線の波長が同じ、すなわち同じ特性X線である場合のみならず、両者の波長が接近してスペクトルが重なる場合にも必要となる。
【0005】
本発明は前記従来の問題に鑑みてなされたもので、FP法で試料の組成を分析する蛍光X線分析装置において、X線管からの特性X線の影響を十分正確に補正できる装置を提供することを目的とする。
【0006】
【課題を解決するための手段】
前記目的を達成するために、本発明の蛍光X線分析装置は、試料に1次X線を照射するX線管と、試料から発生する2次X線の強度を測定する検出手段とを備え、また、その検出手段で測定した蛍光X線の測定強度に基づく理論強度スケールへの換算強度と、試料における各成分の含有率を仮定して計算した蛍光X線の理論強度を対応する成分ごとに対比し、両強度が合致するように、前記仮定した各成分の含有率を逐次近似的に修正計算して、前記各成分の含有率を算出する算出手段を備えている。すなわち、FP法で分析を行う蛍光X線分析装置である。
【0007】
ここで、算出手段が、前記X線管からの特性X線とスペクトルが重なる蛍光X線を分析線とする成分については、その分析線の波長において、組成が既知の試料を用いてあらかじめ求められた前記X線管からの特性X線の散乱線についての理論強度と測定強度との相関を表す不純線装置感度定数に基づいて、分析対象の試料における前記X線管からの特性X線の散乱線の測定強度を理論強度から推定し、前記検出手段による測定強度から差し引いて、分析対象の試料から発生した蛍光X線の測定強度として用いる。
【0008】
本発明の蛍光X線分析装置によれば、FP法において、X線管からの特性X線の散乱線の測定強度を、試料の組成に応じて計算した理論強度から推定するので、X線管からの特性X線の影響を十分正確に補正できる。
【0009】
【発明の実施の形態】
以下、本発明の一実施形態の装置について、図1にしたがって説明する。まず、この装置の構成について説明する。この装置は、試料13が載置される試料台8と、試料13に1次X線2を照射するX線管1と、試料13から発生する蛍光X線等の2次X線4の強度を測定する検出手段10とを備えている。検出手段10は、試料13から発生する2次X線4を分光する分光素子5と、分光素子5で分光された2次X線6の強度を測定する検出器7とを含む。
【0010】
また、この装置は、検出手段10で測定した蛍光X線4の測定強度に基づく理論強度スケールへの換算強度と、試料13における各成分の含有率を仮定して計算した蛍光X線の理論強度を対応する成分ごとに対比し、両強度が合致するように、前記仮定した各成分の含有率を逐次近似的に修正計算して、前記各成分の含有率を算出する算出手段16を備えている。すなわち、この実施形態の装置は、FP法で分析を行う蛍光X線分析装置である。
【0011】
ここで、この装置の算出手段16は、X線管1からの特性X線とスペクトルが重なる蛍光X線4を分析線とする成分については、その分析線の波長において、組成が既知の試料3,23を用いてあらかじめ求められた前記X線管1からの特性X線の散乱線4についての理論強度と測定強度との相関を表す不純線装置感度定数に基づいて、分析対象の試料13における前記X線管1からの特性X線の散乱線4の測定強度を理論強度から推定し、検出手段10による測定強度から差し引いて、分析対象の試料13から発生した蛍光X線4の測定強度として用いる。なお、X線管1からの特性X線には、X線管1の窓に付着した物質やX線管1内の構造物の元素の特性X線、いわゆる不純線と、ターゲット元素の特性X線とがある。また、不純線装置感度定数を求める際に用いる組成が既知の試料3,23には、分析対象の試料13に組成が近似する標準試料3と、X線管1からの特性X線とスペクトルが重なる蛍光X線4を分析線とする成分を含まないブランク試料23とがある。
【0012】
この装置の算出手段16には、あらかじめ、以下のように、蛍光X線装置感度係数A,B,Cおよび不純線装置感度定数a,b,cを求めて記憶させておく。まず、蛍光X線装置感度係数A,B,Cは、この装置で組成が既知の標準試料3について測定した測定強度IFMおよび計算した理論強度IFTを用いて、次式(1)から求められる。
【0013】
IFT=AIFM 2 +BIFM+C …(1)
【0014】
ここで、不純線と同じ波長の蛍光X線4を分析線とする成分を含む試料13を分析しようとする場合を例にとると、そのような成分については、次式(2)にように、標準試料3から発生した蛍光X線4のみの測定強度IFMは、不純線の散乱線4の測定強度IIMを、その波長における検出手段10によるトータル測定強度(バックグラウンドを除去したネット強度)ITMから差し引いて求める。なお、それ以外の成分については、通常のFP法どおり、トータル測定強度ITMをそのまま標準試料3から発生した蛍光X線4のみの測定強度IFMとして用いる。
【0015】
IFM=ITM−IIM …(2)
【0016】
この不純線の散乱線4の測定強度IIMについては、次のようにして推定することができる。まず、不純線の散乱線4についての理論強度と測定強度との相関を表す不純線装置感度定数a,b,cを、前述した通常のFP法で蛍光X線装置感度係数A,B,Cを求めるのと同様に、この装置で、不純線と同じ波長の蛍光X線4を分析線とする成分を含まず組成が既知のブランク試料23について測定した不純線の散乱線4の測定強度IIMおよび計算した不純線の散乱線(トムソン散乱線)の理論強度IITを用いて、次式(3)から求めることができ、あらかじめ算出手段16に記憶させておく。そして、その不純線装置感度定数a,b,cに基づいて、式(3)のように、標準試料3において、不純線の散乱線4の測定強度IIMを、計算した不純線の散乱線の理論強度IITから推定する。ブランク試料23としては、Si O2 やアクリル板を用いることができる。なお、各成分について蛍光X線装置感度係数A,B,Cを求める際に用いる標準試料3は、不純線と同じ波長の蛍光X線4を分析線とする成分を含んでもよい。
【0017】
IIM=aIIT 2 +bIIT+c …(3)
【0018】
単一のブランク試料23を用いるときには、a=c=0とすればよい。
【0019】
不純線と同じ波長の蛍光X線4を分析線とする成分についての蛍光X線装置感度係数A,B,Cおよび不純線装置感度定数a,b,cは、以下のようにして求めることもできる。
【0020】
すなわち、式(3)を式(2)に代入した式を、式(1)に代入して次式(1−2)とする。
【0021】
IFT=A(ITM−aIIT 2 −bIIT−c)2 +B(ITM−aIIT 2 −bIIT−c)+C …(1−2)
【0022】
この装置で組成が既知の標準試料3について測定したトータル測定強度ITMならびに計算した理論強度IFTおよび不純線の散乱線の理論強度IITを用いて、式(1−2)から、不純線と同じ波長の蛍光X線4を分析線とする成分についての蛍光X線装置感度係数A,B,Cおよび不純線装置感度定数a,b,cが、同時に求められる。この場合においても、a=c=0としてもよい。また、用いる標準試料3の中には、不純線と同じ波長の蛍光X線4を分析線とする成分を含まないものがあってもよい。
【0023】
次に、この実施形態の装置の動作について、不純線の影響を補正する場合を例にとり、説明する。試料台8に載置した試料13に1次X線2を照射して、試料13の各成分(元素)から発生する2次X線4の強度を測定する。この測定強度に基づいて、算出手段16が、FP法により、例えば以下の手順で各成分の含有率を算出する。
【0024】
(ステップ1)
各測定強度に基づく換算強度を求める。すなわち、各成分について、前式(1)のように、測定強度IFMを蛍光X線装置感度係数A,B,Cを用いて理論強度スケールに換算して換算強度IFT M とする。ここでは、不純線と同じ波長の蛍光X線4を分析線とする成分についても、不純線の散乱線4の測定強度IIMを差し引かず、トータル測定強度ITMをそのまま試料から発生した蛍光X線4のみの測定強度IFMとして用いる。
【0025】
(ステップ2)
各成分についての換算強度IFT M とその成分の純物質からの蛍光X線の理論強度IFTとの強度比から、各成分の含有率Wの初期値を仮定する。
【0026】
(ステップ3)
そのように仮定した組成から、各蛍光X線と不純線の散乱線の理論強度IFT,IITを計算する。
【0027】
(ステップ4)
不純線と同じ波長の蛍光X線4を分析線とする成分について、計算した不純線の散乱線の理論強度IITを用いて、ステップ1で求めた換算強度IFT M を計算しなおす。すなわち、前式(3)のように、不純線装置感度定数a,b,cに基づいて、不純線の散乱線4の測定強度IIMを、計算した不純線の散乱線の理論強度IITから推定し、その推定した不純線の散乱線4の測定強度IIMを、前式(2)のように、トータル測定強度ITMから差し引いて、試料13から発生した蛍光X線4のみの測定強度IFMとして用いる。そして、その試料13から発生した蛍光X線4のみの測定強度IFMを、前式(1)のように、蛍光X線装置感度係数A,B,Cを用いて理論強度スケールに換算して、次のステップ5のための新たな換算強度IFT M とする。他の成分については、ステップ1で求めた換算強度IFT M をそのまま用いる。
【0028】
(ステップ5)
各成分について、ステップ1または4で求めた換算強度IFT M とステップ3で計算した理論強度IFTとから、次式(4)により含有率の更新を行う。ここで、W(n+1) はn+1回目の含有率、W(n) はn回目の含有率、IFT M(n)はn回目の換算強度(不純線と同じ波長の蛍光X線4を分析線とする成分については、ステップ4で不純線の散乱線4の測定強度IIMを除去済み)、IFT (n) はn回目の理論強度である。
【0029】
W(n+1) =W(n) ×(IFT M(n)/IFT (n) ) …(4)
【0030】
(ステップ6)
各成分について、n回目の含有率とn+1回目の含有率を比較し、すべての成分の含有率の変化が所定値以下になったときに収束とする。収束していないときには、ステップ3以降の手順を繰り返す。
【0031】
すなわち、ステップ1または4で求めた換算強度と、ステップ2で各成分の含有率を仮定してステップ3で計算した蛍光X線の理論強度を、ステップ5、6で対応する成分ごとに対比し、ステップ3〜6を繰り返すことで、両強度が合致するように、仮定した各成分の含有率を逐次近似的に修正計算して、各成分の含有率を算出する。
【0032】
このように、本実施形態の蛍光X線分析装置によれば、FP法において、不純線の散乱線4の測定強度IIMを、試料13の組成に応じて計算した理論強度IITから推定するので、不純線の影響を十分正確に補正できる。
【0033】
以上は、不純線と同じ波長の蛍光X線4を分析線とする成分を含む試料13について、不純線の影響を補正して分析する場合を例にとったが、試料13にX線管1のターゲット元素が含まれる場合にも、同様に対処できる。すなわち、そのような場合には、試料13から発生した蛍光X線4に重ならないように、X線管1のターゲットからの特性X線を、1次フィルタ(図示せず)を用いて、X線管1から発生したX線から除去して1次X線2とするが、完全に除去できない分については、上述の不純線と同様に扱い、その影響を補正する。したがって、X線管1のターゲットからの特性X線の散乱線4の測定強度IIMを、試料13の組成に応じて計算した理論強度IITから推定することにより、X線管1のターゲットからの特性X線の影響を十分正確に補正できる。
【0034】
さて、分析線とX線管1からの特性X線のスペクトルが重なる場合としては、上述のように、分析線とX線管1からの特性X線の波長が同じ、すなわち同じ特性X線(例えばRh −Kα線)である場合の他に、両者の波長が異なるものの接近してスペクトルが重なる場合(例えば、分析線がCd −Kα線で、X線管1からの特性X線がRh −Kβ2 線である場合)があり、この場合にもX線管1からの特性X線の影響の補正が必要である。この場合も、不純線装置感度定数a,b,cは、分析線の波長についてのものであり、分析線の波長における測定強度および理論強度を用いて、式(1)または(1−2)から求められる。
【0035】
【発明の効果】
以上詳細に説明したように、本発明の蛍光X線分析装置によれば、FP法において、X線管からの特性X線の散乱線の測定強度を、試料の組成に応じて計算した理論強度から推定するので、X線管からの特性X線の影響を十分正確に補正できる。
【図面の簡単な説明】
【図1】本発明の一実施形態の蛍光X線分析装置を示す概略図である。
【符号の説明】
1…X線管、2…1次X線、3,23…組成が既知の試料、4…試料から発生する2次X線、10…検出手段、13…分析対象の試料、16…算出手段。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for correcting the influence of characteristic X-rays from an X-ray tube in a fluorescent X-ray analyzer that analyzes the composition of a sample by an FP method.
[0002]
[Prior art]
Conventionally, in fluorescent X-ray analysis, a sample is irradiated with primary X-rays from an X-ray tube, and the intensity of the generated fluorescent X-rays is measured with a detector or the like to analyze the composition of the sample. From the tube, in addition to the characteristic X-rays of the target element, characteristic X-rays of the substances attached to the X-ray tube window and the elements of the structure in the X-ray tube, so-called impure lines, are generated. When this impure line is scattered by the sample and detected by the detector, it cannot be distinguished from fluorescent X-rays of the same wavelength generated from the components in the sample.
[0003]
On the other hand, for example, in the fundamental parameter method, that is, the FP method, the fluorescence X calculated by assuming the converted intensity to the theoretical intensity scale based on the measured intensity of fluorescent X-rays and the content of each component (sample composition) in the sample. The theoretical intensity of the line is compared for each corresponding component, and the assumed content rate of each component is calculated by successive approximation so that both intensities match, and the content rate of each component is calculated. In order to correct for the influence of the line, the scattering intensity of the impure line is measured in advance using a blank sample that does not contain a component that uses fluorescent X-rays of the same wavelength as the impure line as the analysis line, and the analysis line in the sample to be analyzed is analyzed. By subtracting from the measured intensity at the wavelength of 1, the measured intensity of only the fluorescent X-rays generated from the components in the sample was obtained.
[0004]
[Problems to be solved by the invention]
However, since the measured intensity of the impure line is affected by the composition of the sample, the influence of the impure line cannot be accurately corrected when the composition of the blank sample and the sample to be analyzed are greatly different. In addition, it is actually very difficult to prepare a huge number of blank samples and measure the scattering intensity of impure lines in order to deal with samples of all kinds. A similar problem occurs when the target element of the X-ray tube is included in the sample. That is, in such a case, the characteristic X-rays from the target of the X-ray tube are generated from the X-rays generated from the X-ray tube using a primary filter so as not to overlap the fluorescent X-rays generated from the sample. Although it is removed to form a primary X-ray, it cannot be completely removed, and its influence cannot be corrected accurately as in the case of the impure line described above. Further, the correction of the influence of the characteristic X-ray from the X-ray tube is not only performed when the wavelength of the characteristic X-ray from the analysis line and the X-ray tube is the same, that is, the same characteristic X-ray. It is also necessary when the spectrum approaches and the spectra overlap.
[0005]
The present invention has been made in view of the above-described conventional problems, and provides an apparatus capable of sufficiently accurately correcting the influence of characteristic X-rays from an X-ray tube in a fluorescent X-ray analyzer that analyzes the composition of a sample by the FP method. The purpose is to do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an X-ray fluorescence analyzer of the present invention comprises an X-ray tube that irradiates a sample with primary X-rays, and detection means that measures the intensity of secondary X-rays generated from the sample. In addition, the converted intensity to the theoretical intensity scale based on the measured intensity of fluorescent X-rays measured by the detection means and the theoretical intensity of fluorescent X-ray calculated on the assumption of the content of each component in the sample for each corresponding component In contrast to the above, a calculation means for calculating the content ratio of each component by sequentially correcting and calculating the assumed content ratio of each component so that both intensities coincide with each other is provided. That is, it is a fluorescent X-ray analyzer that performs analysis by the FP method.
[0007]
Here, the calculation means uses a sample having a known composition at the wavelength of the analytical line for a component having a fluorescent X-ray whose spectrum overlaps with the characteristic X-ray from the X-ray tube. The characteristic X-ray scattering from the X-ray tube in the sample to be analyzed based on the impure line device sensitivity constant representing the correlation between the theoretical intensity and the measured intensity of the scattered X-ray from the X-ray tube. The measured intensity of the line is estimated from the theoretical intensity, and subtracted from the measured intensity by the detection means, and used as the measured intensity of the fluorescent X-ray generated from the sample to be analyzed.
[0008]
According to the X-ray fluorescence analyzer of the present invention, in the FP method, the measured intensity of scattered X-rays from the characteristic X-ray tube is estimated from the theoretical intensity calculated according to the composition of the sample. The effect of characteristic X-rays from can be corrected sufficiently accurately.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an apparatus according to an embodiment of the present invention will be described with reference to FIG. First, the configuration of this apparatus will be described. This apparatus includes a sample stage 8 on which a sample 13 is placed, an X-ray tube 1 that irradiates the sample 13 with
[0010]
In addition, this apparatus uses the converted intensity to the theoretical intensity scale based on the measured intensity of the fluorescent X-ray 4 measured by the detection means 10 and the theoretical intensity of the fluorescent X-ray calculated by assuming the content of each component in the sample 13. And calculating means 16 for calculating the content ratio of each component by sequentially correcting and calculating the assumed content ratio of each component so that both intensities coincide with each other. Yes. That is, the apparatus of this embodiment is a fluorescent X-ray analyzer that performs analysis by the FP method.
[0011]
Here, the calculation means 16 of this apparatus, for a component whose analysis line is the fluorescent X-ray 4 whose spectrum overlaps with the characteristic X-ray from the X-ray tube 1, is a sample 3 whose composition is known at the wavelength of the analysis line. , 23 based on the impure line device sensitivity constant representing the correlation between the theoretical intensity and the measured intensity of the scattered X-ray 4 of the characteristic X-ray from the X-ray tube 1 obtained in advance, using the sample 13 to be analyzed. The measured intensity of the scattered X-ray 4 of the characteristic X-ray from the X-ray tube 1 is estimated from the theoretical intensity, and subtracted from the measured intensity by the detection means 10 to obtain the measured intensity of the fluorescent X-ray 4 generated from the sample 13 to be analyzed. Use. The characteristic X-rays from the X-ray tube 1 include the characteristic X-rays of the substances attached to the window of the X-ray tube 1 and the elements of the structure in the X-ray tube 1, so-called impure lines, and the characteristic X of the target element. There is a line. Samples 3 and 23 having known compositions used for determining the impure line device sensitivity constant include standard sample 3 whose composition approximates that of sample 13 to be analyzed, and characteristic X-rays and spectra from X-ray tube 1. There is a blank sample 23 which does not contain a component having the overlapping fluorescent X-rays 4 as analysis lines.
[0012]
In the calculation means 16 of this apparatus, fluorescent X-ray apparatus sensitivity coefficients A, B, and C and impurity line apparatus sensitivity constants a, b, and c are obtained and stored in advance as follows. First, the X-ray fluorescence apparatus sensitivity coefficients A, B, and C are obtained from the following equation (1) using the measured intensity I FM and the calculated theoretical intensity I FT measured for the standard sample 3 whose composition is known with this apparatus. It is done.
[0013]
I FT = AI FM 2 + BI FM + C (1)
[0014]
Here, taking as an example a case where a sample 13 including a component having a fluorescent X-ray 4 having the same wavelength as an impure line as an analysis line is to be analyzed, such a component is expressed by the following equation (2). The measured intensity I FM of only the fluorescent X-ray 4 generated from the standard sample 3 is the total measured intensity (net intensity with the background removed) of the measured intensity I IM of the scattered scattered light 4 of the impure line at the wavelength. ) Subtract from ITM. For other components, the total measurement intensity I TM is used as it is as the measurement intensity I FM of only the fluorescent X-rays 4 generated from the standard sample 3 as in the normal FP method.
[0015]
I FM = I TM −I IM (2)
[0016]
The measured intensity I IM of the impure scattered ray 4 can be estimated as follows. First, impure line device sensitivity constants a, b and c representing the correlation between the theoretical intensity and the measured intensity of the scattered scattered light 4 of the impure line are converted into X-ray fluorescence apparatus sensitivity coefficients A, B and C by the above-described normal FP method. In this apparatus, the measured intensity I of the impure line scattered ray 4 measured with respect to the blank sample 23 having a known composition and not including the component having the fluorescent X-ray 4 having the same wavelength as the impure line as the analysis line. It can be obtained from the following equation (3) using the theoretical intensity I IT of IM and the calculated impurity scattered ray (Thomson scattered ray), and is stored in the calculating means 16 in advance. Then, based on the impure line device sensitivity constants a, b, and c, the measured intensity I IM of the impure line scattered line 4 is calculated from the impure line scattered line in the standard sample 3 as shown in Equation (3). Estimated from the theoretical intensity I IT of . As the blank sample 23, SiO 2 or an acrylic plate can be used. In addition, the standard sample 3 used when calculating | requiring fluorescent X-ray apparatus sensitivity coefficient A, B, C about each component may also contain the component which uses the fluorescent X-ray 4 of the same wavelength as an impure line as an analysis line.
[0017]
I IM = aI IT 2 + bI IT + c (3)
[0018]
When a single blank sample 23 is used, a = c = 0 may be set.
[0019]
The X-ray apparatus sensitivity coefficients A, B, and C and the impurity apparatus sensitivity constants a, b, and c for components using the fluorescent X-ray 4 having the same wavelength as that of the impure line as the analysis line may be obtained as follows. it can.
[0020]
That is, an expression obtained by assigning expression (3) to expression (2) is assigned to expression (1) to obtain the following expression (1-2).
[0021]
I FT = A (I TM −aI IT 2 −bI IT −c) 2 + B (I TM −aI IT 2 −bI IT −c) + C (1-2)
[0022]
Using the total measured intensity I TM measured for the standard sample 3 whose composition is known with this apparatus, the calculated theoretical intensity I FT, and the theoretical intensity I IT of the impure line scattered line, the impure line is obtained from the equation (1-2). X-ray apparatus sensitivity coefficients A, B, and C and impure line apparatus sensitivity constants a, b, and c for components having the X-ray fluorescence 4 having the same wavelength as the analysis line are simultaneously obtained. Also in this case, a = c = 0 may be set. Further, the standard sample 3 to be used may be one that does not include a component having the fluorescent X-ray 4 having the same wavelength as the impurity line as an analysis line.
[0023]
Next, the operation of the apparatus of this embodiment will be described by taking as an example the case of correcting the influence of impure lines. The sample 13 placed on the sample stage 8 is irradiated with the
[0024]
(Step 1)
Calculate the converted intensity based on each measured intensity. That is, for each component, the measured intensity I FM is converted into a theoretical intensity scale using the fluorescent X-ray apparatus sensitivity coefficients A, B, and C as converted intensity I FT M as in the previous equation (1). Here, for the components to be analyzed line X-ray fluorescence 4 having the same wavelength as impure line, not deducted measured intensity I IM scattered radiation 4 of impure lines, fluorescent X generated total measured intensity I TM directly from the sample Used as measured intensity IFM of line 4 only.
[0025]
(Step 2)
From the intensity ratio between the converted intensity I FT M for each component and the theoretical intensity I FT of fluorescent X-rays from the pure substance of that component, the initial value of the content W of each component is assumed.
[0026]
(Step 3)
From the assumed composition, the theoretical intensities I FT and I IT of the scattered X-rays and impure rays are calculated.
[0027]
(Step 4)
The component to be analyzed line X-ray fluorescence 4 having the same wavelength as impure line, using the theoretical intensity I IT of scattered radiation calculated impure lines, recalculate the converted intensity I FT M obtained in step 1. That is, as shown in the previous equation (3), the measured intensity I IM of the impure line scattered radiation 4 is calculated based on the impure line apparatus sensitivity constants a, b, and c, and the calculated impulsive scattered light theoretical intensity I IT is calculated. The measured intensity I IM of the estimated impulsive scattered radiation 4 is subtracted from the total measured intensity I TM as shown in the previous equation (2), and only the fluorescent X-ray 4 generated from the sample 13 is measured. Used as intensity I FM . Then, the measured intensity I FM of only the fluorescent X-ray 4 generated from the sample 13 is converted into a theoretical intensity scale using the fluorescent X-ray apparatus sensitivity coefficients A, B, and C as shown in the previous equation (1). The new converted intensity I FT M for the
[0028]
(Step 5)
For each component, the content rate is updated by the following equation (4) from the converted intensity I FT M obtained in step 1 or 4 and the theoretical intensity I FT calculated in step 3. Here, W (n + 1) is the content of the n + 1th time, W (n) is the content of the nth time, I FT M (n) is the converted intensity of the nth time (fluorescent X-ray 4 having the same wavelength as the impurity line ) For the component having the analysis line as the analysis line, the measured intensity I IM of the impure line scattered line 4 has been removed in step 4), and I FT (n) is the nth theoretical intensity.
[0029]
W (n + 1) = W (n) * ( IFTM (n) / IFT (n) ) (4)
[0030]
(Step 6)
For each component, the n-th content rate and the (n + 1) -th content rate are compared, and convergence is determined when the change in the content rate of all the components becomes a predetermined value or less. If not converged, the procedure from step 3 is repeated.
[0031]
That is, the converted intensity obtained in step 1 or 4 and the theoretical intensity of fluorescent X-ray calculated in step 3 assuming the content of each component in
[0032]
As described above, according to the fluorescent X-ray analyzer of the present embodiment, the measured intensity I IM of the impure-line scattered radiation 4 is estimated from the theoretical intensity I IT calculated according to the composition of the sample 13 in the FP method. Therefore, the influence of the impure line can be corrected sufficiently accurately.
[0033]
The above is an example in which the sample 13 including the component having the fluorescent X-ray 4 having the same wavelength as the impurity line as the analysis line is analyzed while correcting the influence of the impurity line. The same can be dealt with when the target element is included. That is, in such a case, the characteristic X-rays from the target of the X-ray tube 1 are converted into X-rays using a primary filter (not shown) so as not to overlap the fluorescent X-rays 4 generated from the sample 13. The
[0034]
Now, in the case where the spectrum of the characteristic X-ray from the X-ray tube 1 overlaps, as described above, the wavelength of the characteristic X-ray from the analytical line and the X-ray tube 1 is the same, that is, the same characteristic X-ray ( In addition to the case of Rh-Kα ray, for example, when the two wavelengths are different but the spectra overlap each other (for example, the analysis line is a Cd-Kα ray and the characteristic X-ray from the X-ray tube 1 is Rh − If a Kbeta 2-wire) there is, it is necessary to correct the influence of the characteristic X-rays from the X-ray tube 1 in this case. Also in this case, the impure wire device sensitivity constants a, b, and c are for the wavelength of the analytical line, and the measured intensity and theoretical intensity at the wavelength of the analytical line are used to calculate the equation (1) or (1-2). It is requested from.
[0035]
【The invention's effect】
As described above in detail, according to the fluorescent X-ray analysis apparatus of the present invention, in the FP method, the theoretical intensity calculated from the measured intensity of scattered X-rays from the X-ray tube according to the composition of the sample is calculated. Therefore, the influence of characteristic X-rays from the X-ray tube can be corrected sufficiently accurately.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an X-ray fluorescence analyzer according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 2 ... Primary X-ray, 3,23 ... Sample with known composition, 4 ... Secondary X-ray generated from sample, 10 ... Detection means, 13 ... Sample to be analyzed, 16 ... Calculation means .
Claims (1)
試料から発生する2次X線の強度を測定する検出手段と、
その検出手段で測定した蛍光X線の測定強度に基づく理論強度スケールへの換算強度と、試料における各成分の含有率を仮定して計算した蛍光X線の理論強度を対応する成分ごとに対比し、両強度が合致するように、前記仮定した各成分の含有率を逐次近似的に修正計算して、前記各成分の含有率を算出する算出手段とを備えた蛍光X線分析装置において、
前記算出手段が、前記X線管からの特性X線とスペクトルが重なる蛍光X線を分析線とする成分については、その分析線の波長において、組成が既知の試料を用いてあらかじめ求められた前記X線管からの特性X線の散乱線についての理論強度と測定強度との相関を表す不純線装置感度定数に基づいて、分析対象の試料における前記X線管からの特性X線の散乱線の測定強度を理論強度から推定し、前記検出手段による測定強度から差し引いて、分析対象の試料から発生した蛍光X線の測定強度として用いることを特徴とする蛍光X線分析装置。An X-ray tube that irradiates the sample with primary X-rays;
Detection means for measuring the intensity of secondary X-rays generated from the sample;
The converted intensity to the theoretical intensity scale based on the measured intensity of fluorescent X-rays measured by the detection means and the theoretical intensity of fluorescent X-ray calculated on the assumption of the content of each component in the sample are compared for each corresponding component. In the fluorescent X-ray analysis apparatus comprising: a calculation means for calculating the content ratio of each component by sequentially correcting and calculating the content ratio of each assumed component so that the two intensities match.
For the component in which the calculation means uses the fluorescent X-ray whose spectrum overlaps with the characteristic X-ray from the X-ray tube as the analysis line, the above-mentioned calculation was performed using a sample having a known composition at the wavelength of the analysis line. Based on the impure line device sensitivity constant representing the correlation between the theoretical intensity and the measured intensity of the characteristic X-ray scattered ray from the X-ray tube, the characteristic X-ray scattered ray from the X-ray tube in the sample to be analyzed A fluorescent X-ray analysis apparatus characterized in that a measurement intensity is estimated from a theoretical intensity and is subtracted from a measurement intensity obtained by the detection means and used as a measurement intensity of fluorescent X-rays generated from a sample to be analyzed.
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