JPH10282026A - Simultaneous quantitative analysis method for state of element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which performs a quick and handy quantitative analysis for multiple states of elements to be measured individually when the elements of such multiple states mingle in a sample to be measured. SOLUTION: As for an element to be measured, standard Auger electron spectrums are obtained from more than one kind of standard substances merely different in chemical bond states and extended or reduced in the direction of intensity as axis while being shifted in the direction of Auger electron dynamic energy as axis to combine. Thus, a sum spectrum is obtained and is compared to an Auger electron spectrum of the element to be measured in the sample to be measured to estimate the state of the element to be measured and the relative existence quantity thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simultaneous and quantitative analysis of element states.

[0002]

2. Description of the Related Art Conventionally, as a method of analyzing the state of an element, a method using a photoelectron binding energy value peculiar to the same element in X-ray photoelectron spectroscopy (hereinafter referred to as method 1), and the same spectroscopy. A method using Auger parameter values (hereinafter referred to as
Called method 2. ), Electron spin resonance spectroscopy (hereinafter, referred to as method 3) and other instrumental analysis methods, and various titration methods (hereinafter, referred to as method 4) have been used. However, when the same element in multiple states is mixed in the sample to be measured,
In order to determine these states and amounts individually, it is necessary to use a special method, and the method cannot be carried out depending on the method and / or the kind of element.

[0003] Method 1 utilizes the fact that the bond energy value of a photoelectron inherent to an element differs depending on the chemical bond state of the same element, and changes the chemical bond state of a known substance having the same value as the bond energy value of the sample to be measured. In addition, if the same substance is present in a plurality of chemical bonding states in the substance to be measured, the spectrum is separated into multiple peaks by a mathematical process called waveform separation. Quantitative analysis can also be performed. However, when the binding energies of a plurality of types of chemical bonding state are close to each other, it is difficult to assign them.

[0004] In the method 2, the Auger parameter value AP or AP 'peculiar to the element is generally used even when the binding energy value of the photoelectron peculiar to the element is close to a plurality of kinds of chemical bonding states.
(The unit is eV (electron volt), where AP = E
_{A -E p = K p -K A} , the binding energy value of E _A is element-specific Auger electron binding energy value of E _p is characteristic of element optoelectronic, K _p is the kinetic energy value of the photoelectron K
_{p = E X -E p, E} X is the energy value of the measurement when X-ray irradiation, K _A is the kinetic energy value of the Auger electron K _{A
= E X -E A, AP '} = E X -AP = E X -E A + E p
= K _A + E _p ), which is based on the relatively different values, and belongs to the chemical bonding state of a known substance exhibiting the value corresponding to the Auger parameter value of the sample to be measured. However, the Auger electron spectrum is composed of a number of peaks with different generation mechanisms overlapping each other, and the Auger parameter is calculated using only the kinetic energy value of a specific type of peak. When the same element exists in the state, there is a problem in that only one kind of state, which is the main component, can be known.

[0005] Method 3 is an analysis method utilizing the magnetic properties of a sample, and poses a problem in that the substance to be measured is limited to those having certain magnetic properties.

Method 4 is a method for individually quantifying the same element in a plurality of states existing in a sample to be measured by utilizing properties inherent to the state of each element such as a difference in ease of reaction.
Problems arise in that a large amount of sample is required, that the operation content differs depending on the type of element and / or the type of state, and that generally a large number of complicated operations are required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to replace the conventional method for analyzing the state of elements, that is, when the same element is present in a plurality of states in a sample, these states are individually determined. Another object of the present invention is to provide a rapid quantitative analysis method.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have compared the Auger electron spectrum shape in X-ray photoelectron spectroscopy with the sum spectrum shape obtained by combining a standard spectrum. As a result, the inventors have found that the same element in a plurality of states can be separated and quantified, thereby completing the present invention.

That is, in the analysis method of the present invention, two or more kinds of standard substances containing the element to be measured and having different chemical bonding states are measured by X-ray electron spectroscopy, and the chemical bonding of each of the elements to be measured is performed. The standard Auger electron spectrum corresponding to the state is obtained, and these standard Auger electron spectra are expanded and contracted in the direction of the intensity axis by the intensity parameter and shifted in the direction of the Auger electron kinetic energy axis. The spectra obtained from the Auger electron spectra are combined with each other to produce a sum spectrum, and the sample is measured by X-ray spectroscopy. By determining the intensity parameter and the shift amount in the direction of the Auger electron kinetic energy axis so that the two coincide with each other. The is elemental and quantitative simultaneous analysis method characterized by estimating the state and relative abundance of those under measurement element.

The analysis method of the present invention utilizes the Auger electron spectrum shape of an element measured by X-ray photoelectron spectroscopy when analyzing the state and quantitative analysis of the element in the sample to be measured. In addition, the analysis method of the present invention is different from a method based on ordinary waveform separation using a specific function as a shape of an Auger electron spectrum, in which elements to be measured having different bonding states obtained by measurement of two or more kinds of standard substances are used. Using the measured standard Auger electron spectrum corresponding to, the appropriate amount is shifted in the direction of the Auger electron kinetic energy axis, and the intensity ratio between the standard Auger electron spectra is changed according to the relative abundance of the corresponding bonding state. A series of sum spectra obtained in advance, focusing on only the similarity of the shape of the spectra, and comparing the Auger electron spectra of the element to be measured in the sample to be measured with this, allowing for easy and quick waveform separation Quantitative analysis to estimate the relative abundance of the state analysis from the obtained results It is those that can be carried out.

In particular, when the element to be measured in the sample to be measured has two kinds of bonding states, the first standard substance containing the element to be measured is different from the first standard substance in the chemical bonding state. Using two kinds of standard materials of a second standard material containing an element,
A first standard Auger electron spectrum obtained from the first standard substance has a first intensity parameter ka (0 ≦ k ≦ 1,
a is a constant for normalization), and a second intensity parameter (1-k) is added to a first spectrum obtained by multiplying the first spectrum obtained by multiplying the first standard spectrum obtained by the second standard substance.
When producing a sum spectrum using the second spectrum obtained by multiplying a, the relative distance ΔK in the Auger electron kinetic energy axis direction between the first standard Auger electron spectrum and the second standard Auger electron spectrum is calculated as A series of sum spectra is prepared by changing the value of k for each ΔK, and focusing only on the similarity of the shapes of the spectra, the Auger electron of the element to be measured in the sample to be measured is changed. Comparing the spectrum and the sum spectrum, shifting the coincident sum spectrum in the direction of the Auger electron kinetic energy axis to match the Auger electron spectrum of the element to be measured in the sample to be measured. , For each of the plurality of ΔK, the value of k is set to 0
A series of sum spectra obtained in a stepwise manner from 1 to 1 are prepared in advance, and the Auger electron spectra of the element to be measured in the sample to be measured obtained by measuring the sample to be measured by X-ray spectroscopy are And a method for simultaneous analysis of elemental states and quantification, characterized by comparison with a series of sum spectra.

The analysis of the state of the element to be measured in the sample to be measured is carried out based on the type of each standard spectrum used for preparing the sum spectrum and the Auger electron kinetic energy value thereof, and the quantitative analysis of the state is carried out for the element. Can be carried out by multiplying the quantitative value of the total amount of the same element obtained in the photoelectron spectrum measurement by the relative ratio of the intensity parameter of each standard spectrum used to create the sum spectrum.

Samples to be analyzed in the analysis method of the present invention are limited to solids that can be measured by X-ray photoelectron spectroscopy. There is no particular limitation.

The element to be measured is not particularly limited as long as it has an Auger electron spectrum within the measurable range of the apparatus to be used, and the sample to be measured easily has an Auger electron spectrum with a clear shape. What is necessary is just to include the element to be measured in a sufficient amount to obtain the target element.

The standard substance used in the analysis method of the present invention is:
The element to be measured preferably contains only a specific bonding state, and it is preferable to use a standard substance corresponding to each of all the bonding states that may be contained in the sample to be measured. The form of the standard substance is not particularly limited, but it is preferable to use the same form for a series of standard substances. The reference materials used are:
Elemental elements, oxides, halides and the like can be exemplified, but other compounds, alloys, amorphous and the like may be used depending on the purpose of use. In addition, even if the valences are the same, when the standard Auger electron spectra are significantly different, the analysis may be performed as separate standard Auger electron spectra.

[0016]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

In the present embodiment, 3d silver was measured using an X-ray photoelectron spectrometer (trade name “ESCA-750” manufactured by Shimadzu Corporation).
The orbital photoelectron spectrum and the MNN Auger electron spectrum of silver having an Auger electron kinetic energy value in the range of 330 to 370 eV (electron volt) were measured.

At the time of measurement, metallic silver was ionized + 1-valently by an ion etching apparatus (accessory), and irradiated with Ar gas accelerated at an acceleration voltage of 1 kV for several minutes to remove surface contaminants and surface oxides. The measurement was performed later, and the sample to be measured and the powdery silver compound such as silver oxide (I) were molded with a tablet molding machine (apparatus accessory, operating pressure: 120 kgf / cm ² ), and the smooth surface was measured.

FIG. 1 shows metallic silver (accessory accessory), silver oxide (I) (Katayama Chemical Industry, special grade reagent), silver fluoride (Kanto Chemical Industry, purity 99% reagent), silver chloride (Wako Pure Chemical Industries, Ltd.) Industrial, 99.5% purity reagent), silver bromide (Wako Pure Chemical Industries,
90% pure reagent), silver iodide (Wako Pure Chemical Industries, purity 9)
2 shows the results of measuring the MNN Auger electron spectrum of silver in 0% reagent). Note that the horizontal axis of the figure indicates the Auger electron kinetic energy value K _A (unit is electron volt), and the vertical axis indicates the detection intensity (arbitrary unit). In addition, each substance was measured several times to confirm the reproducibility of the measurement results.

In the Auger electron spectrum of FIG. 1, the kinetic energy value K of the silver M ₄ VV Auger electron indicated by the arrow is shown.
Calculating the Auger parameter AP 'than _A, shows the relationship between the binding energy E _p of silver 3d orbital photoelectrons same substance which is separately measured in Figure 2. In the figure, ○ indicates metallic silver, black square indicates silver oxide (I), upward black square indicates silver fluoride, downward black square indicates silver chloride, ● indicates silver bromide, and Δ indicates iodide. Shows the value of silver. In addition, data of substances other than silver metal indicated by a circle in the figure indicate that AP 'values are almost the same,
The silver in the 0-valent state and the + 1-valent state are distinguished from the value.

Example 1 FIG. 3A shows the result of measuring the MNN Auger electron spectrum of silver using silver nitrate (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) as a sample to be measured (the horizontal axis is Auger electron). The kinetic energy value K _A (the unit is electron volt), and the vertical axis shows the detection intensity (arbitrary unit)). This spectrum shows a complicated shape as compared with the spectrum of the substance shown in FIG. 1, and it was presumed that silver in a plurality of states was mixed.

Using metallic silver (accessory equipment) and silver oxide (I) (Katayama Chemical Industry, special grade reagent) as standard substances,
The MNN Auger electron spectrum of silver was measured, and two kinds of standard Auger electron spectra were obtained (A and B in FIG. 1).

The relative distance of these two standard spectra in the Auger electron kinetic energy axis direction (difference in Auger electron kinetic energy) ΔK (for example, M
The difference in kinetic energy between the ₄ VV Auger electron peaks) was 2 eV in the actual measurement, but it was 1.6, 2.0,
Intensity parameters ka and (1−k) · a (0 ≦ k ≦ 1, respectively) that expand and contract the standard Auger electron spectrum in the intensity direction are set for each of the three stages of 2.4 eV.
The value of k in (a is a constant for normalization) was changed in 11 steps from 0 to 1 in increments of 0.1 to produce a sum spectrum. At this time, as for the position on the Auger electron kinetic energy axis, the measured value is used as it is for the first standard Auger electron spectrum, and the relative distance ΔK is the set value for the second standard Auger electron spectrum. Was shifted as follows. Further, even if ΔK is changed, k =
For 0 and k = 1, the shape of the sum spectrum obtained is the same, so that the total number of sum spectra produced as described above is 29.

The position on the Auger electron kinetic energy axis is not considered, and the shape of the Auger electron spectrum shown in FIG. In contrast, as the sum spectrum that best matches, ΔK = 2.0 eV and k =
0.1 was selected. Further, the sum spectrum is 1.1 eV in the direction of the Auger electron kinetic energy axis so as to match the Auger electron spectrum shown in FIG.
Shifted. Sum spectrum finally obtained (solid line)
To show it to the composing two spectra Figure 3 (dashed and dotted) (b) (abscissa binding energy E _A value (in electron volts), the vertical axis and 100 the highest peak intensity relative Strength). As a result, in this example, the value of k in the strength parameter was 0.1, so that 0-valent silver and + 1-valent silver were present in the sample to be measured in a ratio of 1: 9 in silver nitrate. It is estimated that

The kinetic energy value K _{A of} the silver M ₄ VV Auger electron peak shown by the arrow in the standard Auger electron spectrum shown in FIG. 1 and the two spectra used to produce the sum spectrum shown in FIG. Auger parameter AP 'value calculated from the kinetic energy value K _a of the peak corresponding to M ₄ VV Auger electrons, shown in FIG. 4 separately measured relationship between the binding energy E _p of silver 3d orbital photoelectron in silver nitrate . In the figure, the squares indicate values obtained from a spectrum using metallic silver as a standard (component 1), and the black squares indicate values obtained from a spectrum using silver oxide (I) as a standard (component 2). In addition, ○ and ● indicate the same values of silver metal, silver oxide (I), silver fluoride, silver chloride, silver bromide, and silver iodide as shown in FIG.

As is apparent from FIG. 4, the value (black square) obtained from the spectrum (component 2) using silver oxide (I) as a standard substance, which is the analysis result of silver nitrate of the sample to be measured, is +1.
Value almost identical to the value in the case of silver (valent), and the value obtained from the spectrum (component 1) using the other metallic silver as a standard substance (□)
Mark) shows a value closer to that of zero-valent silver, and all of the silver in the silver nitrate as the sample to be measured was +1.
It was presumed that a part (about 10%) was in a metallic silver state although it should be in a valence state. This means
This is a finding that could not be known by other conventional methods, and shows the usefulness of the analysis method of the present invention.

(Example 2) Using silver sulfate (manufactured by Wako Pure Chemical Industries, special grade reagent, 3 years or more after opening) as a sample to be measured, the spectral shapes were compared in the same manner as in Example 1,
A sum spectrum having the same shape was selected and shifted in the direction of the Auger electron kinetic energy axis to obtain a final sum spectrum. FIG. 5 (a) shows the Auger electron spectrum of the sample to be measured, FIG. 5 (b) shows the determined sum spectrum (solid line), and two spectra (broken line and dotted line) constituting the sum spectrum (both figures are horizontal). The axis indicates the Auger electron kinetic energy value K _A and the vertical axis indicates the detected intensity.) The values of ΔK and k used for producing the selected sum spectrum were 2.4 eV and 0.3, respectively. Further, the shift amount for making the selected sum spectrum coincide with the Auger electron spectrum shown in FIG. 5A was 1.2 eV. As in Example 1, k in the obtained intensity parameters
From the value (k = 0.3), the silver sulfate of the sample to be measured contains:
It was estimated that zero-valent silver and monovalent silver were present in a ratio of 3: 7.

Further, similarly to the first embodiment, M ₄ V of two spectra constituting the sum spectrum shown in FIG.
FIG. 6 shows the Auger parameter AP ′ value calculated from the kinetic energy value K _A of V Auger electrons. In the figure, the squares indicate values obtained from a spectrum using metallic silver as a standard (component 1), and the black squares indicate values obtained from a spectrum using silver oxide (I) as a standard (component 2). In addition, circles and circles indicate Fig. 2.
The values of metallic silver, silver oxide (I), silver fluoride, silver chloride, silver bromide and silver iodide are the same as those shown in Table 1. From FIG. 6, the value (black square) obtained from the spectrum (component 2) using silver oxide (I) as a standard substance almost coincides with the value in + 1-valent silver, and the other metal silver was used as a standard. It was confirmed that the value obtained from the spectrum of the substance (component 1) (marked with □) was closer to the value of zero-valent silver than that of the substance. It was estimated that (about 30%) of silver was in a metallic silver state. Since the sample to be measured in this example was left in the laboratory for several years after opening, there is a high possibility that a state change has occurred, and by using the analysis method of the present invention, the state during storage of the reagent A change, that is, generation of zero-valent silver was confirmed.

Example 3 Using a zeolite powder containing silver as a sample to be measured, the spectrum shapes were compared in the same manner as in Example 1, a sum spectrum having the same shape was selected, and the Auger electron kinetic energy axis was determined. To obtain the final sum spectrum. FIG. 7A shows the Auger electron spectrum of the sample to be measured, FIG. 7B shows the determined sum spectrum (solid line), and two spectra (broken line and dotted line) constituting the same (both figures show the horizontal axis). Represents the Auger electron kinetic energy value K _A , and the vertical axis represents the detection intensity). The values of ΔK and k used for producing the selected sum spectrum were 2.4 eV and 0.5, respectively. Further, the shift amount for making the selected sum spectrum coincide with the Auger electron spectrum shown in FIG. 7A was 0.8 eV. The standard Auger electron spectrum used to create the selected sum spectrum was obtained from metallic silver and silver (I) oxide, and the M ₄ VV Auger electrons of the two spectra that comprised the selected sum spectrum. From the Auger electron kinetic energy value K _A , the silver in the sample to be measured has both a zero valence state and a +1 valence state, and the value of k in the intensity parameter (k = 0.
From 5), it was confirmed that the zeolite of the sample to be measured contained silver in the 0-valent state and the + 1-valent state in a ratio of 5: 5.

Using the sample, the 3d orbital photoelectron spectrum of silver and the 2p orbital photoelectron spectrum of silicon as a reference were measured in the same apparatus, and the value obtained by quantitatively analyzing the atomic ratio of silver to silicon in all states (silicon). As a result of individually quantitatively analyzing the zero-valent state and the + 1-valent state of the sample to be measured by dividing silver (9.5 silver atoms per 100 atoms) into the ratio of 5: 5, the zero-valent state was obtained. And + 1-valent silver were 4.8 per 100 silicon atoms.

(Example 4) Using a zeolite powder containing silver, which is different from that analyzed in Example 3 as a sample to be measured, silver chloride (purity of Wako Pure Chemical Industries, Ltd. The analysis was performed in the same manner as in Example 3 except that 99.5% reagent) was used. As a result, the value of k in the strength parameter becomes 0.3, and the zero-valent state and +1
It was confirmed that the valence state was present at a ratio of 3: 7. Further, in the same manner as in Example 3, the atomic ratio of silver in all states to silicon (12.2 silver atoms to 100 silicon atoms).
) In the ratio of 3: 7, the silver in the zero valence state in the sample to be measured is 3.7 per 100 silicon atoms.
Silver in the +1 valence state is 8.5 per 100 silicon atoms.
Was individual.

[0032]

As described above in detail, according to the analysis method of the present invention, when the same element in a plurality of states is mixed in a sample to be measured, the states and amounts thereof are individually and quickly and easily determined. be able to.

[Brief description of the drawings]

FIG. 1. MN of silver in metallic silver, silver oxide and silver halide
It is a figure which shows an N Auger electron spectrum.

FIG. 2 3d of silver in metallic silver, silver oxide and silver halide
It is a diagram showing a binding energy E _p and Auger parameter AP 'values of orbital photoelectron.

FIG. 3 (a) MN of silver in silver nitrate measured in Example 1
It is a figure which shows an N Auger electron spectrum, (b) the sum spectrum which agrees with this, and the spectrum which comprises it.

In [4] Example 1, silver 3d orbital photoelectron in silver nitrate binding energy E _p Auger parameter A
It is a figure which shows the relationship with P 'value.

FIG. 5 (a) MN of silver in silver sulfate measured in Example 2
It is a figure which shows an N Auger electron spectrum, (b) the sum spectrum which agrees with this, and the spectrum which comprises it.

In [6] Example 2 is a diagram showing the relationship between the binding energy E _p Auger parameter AP 'values of 3d orbital photoelectron in silver sulfate.

7A is a diagram showing an MNN Auger electron spectrum of silver in zeolite measured in Example 3, and FIG. 7B is a diagram showing a sum spectrum corresponding thereto and a spectrum constituting the same.

Claims (3)

[Claims] 1. An X-ray electron spectroscopy method for measuring two or more kinds of standard substances containing an element to be measured and having different chemical bonding states, and a standard Auger electron corresponding to each of the chemical bonding states of the element to be measured. A spectrum was obtained, and these standard Auger electron spectra were obtained by expanding and contracting these standard Auger electron spectra in the intensity axis direction by the intensity parameter and shifting them in the Auger electron kinetic energy axis direction. The spectra are combined with each other to produce a sum spectrum, and the measured sample is compared with an Auger electron spectrum of the measured element in the measured sample obtained by measuring the sample by the X-ray spectroscopy so that the two agree with each other. By determining the intensity parameter and the shift amount in the direction of the Auger electron kinetic energy axis in advance, the state and the state of the element to be measured are determined. A method for simultaneous analysis of the states of elements and quantitative analysis, characterized by estimating the relative abundance of these states. 2. The method according to claim 1, further comprising the steps of: using a first standard substance containing the element to be measured and a second standard substance containing the element to be measured having a different chemical bonding state from the first standard substance. A first spectrum obtained by multiplying a first standard Auger electron spectrum obtained from one standard substance by a first intensity parameter ka (0 ≦ k ≦ 1, a is a constant for normalization); In producing a sum spectrum using a second standard Auger electron spectrum obtained from the second standard substance and a second spectrum obtained by multiplying the second intensity parameter (1−k) · a, the first standard is used. The relative distance ΔK in the Auger electron kinetic energy axis direction between the standard Auger electron spectrum and the second standard Auger electron spectrum is changed, and the value of k is changed for each ΔK to produce a series of sum spectra. Focusing only on the similarity of the shape of the spectrum, comparing the Auger electron spectrum and the sum spectrum of the element to be measured in the sample to be measured, shifting the coincident sum spectrum in the direction of the Auger electron kinetic energy axis. 2. The method for simultaneous analysis of the state and quantitative determination of an element according to claim 1, wherein the element is made to coincide with the Auger electron spectrum of the element to be measured in the sample to be measured. 3. The value of k is set to 0 for each of a plurality of ΔKs.
A series of sum spectra obtained in a stepwise manner from 1 to 1 are prepared in advance, and the Auger electron spectra of the element to be measured in the sample to be measured obtained by measuring the sample to be measured by X-ray spectroscopy are 3. The method for simultaneous analysis of element states and quantitative determination according to claim 2, wherein the method is compared with a series of sum spectra of the following.