阅读说明：本技术 气体分析方法及装置 (Gas analysis method and apparatus ) 是由 川口真一 于 2019-03-05 设计创作，主要内容包括：本发明提供一种不需要预处理而能够对腐蚀性气体中的杂质、氟化氢进行测定、分析的高灵敏度的方法及装置。所使用的是一种气体分析方法及气体分析装置,其通过傅里叶变换红外光谱仪来对包含腐蚀性气体的试样中的氟系气体进行测定,其中,傅里叶变换红外光谱仪设置有具有InGaAs探测元件的探测器和光程长度0.01m～2m的单程气室,室窗由耐腐蚀性材料构成,测定区域为波数3800～14300cm<Sup>-1</Sup>,根据规定波数的光在所述试样中的吸收量与预设的校正曲线来对氟系气体浓度进行定量分析。(The invention provides a highly sensitive method and apparatus for measuring and analyzing impurities and hydrogen fluoride in a corrosive gas without requiring pretreatment. A gas analysis method and a gas analysis apparatus are used for measuring fluorine-containing gas in a sample containing corrosive gas by a Fourier transform infrared spectrometer, wherein the Fourier transform infrared spectrometer is provided with a detector having an InGaAs detection element and a single-pass gas chamber having an optical path length of 0.01m to 2m, a chamber window is made of a corrosion-resistant material, and a measurement region has a wave number of 3800 to 14300cm ‑1 Quantitatively analyzing the fluorine-containing gas concentration based on the absorption amount of light of a predetermined wave number in the sample and a predetermined calibration curve。)

1. A gas analysis method for measuring a fluorine-containing gas in a sample containing a corrosive gas by a Fourier transform infrared spectrometer, wherein,

the Fourier transform infrared spectrometer is provided with a detector with an InGaAs detection element and a one-way gas chamber with the optical path length of 0.01 m-2 m,

the chamber window is constructed of a corrosion resistant material,

the wave number of the measuring region is 3800-14300 cm^-1，

The fluorine-containing gas concentration is quantitatively analyzed from the absorption amount of light of a predetermined wave number in the sample and a preset calibration curve.

2. The method of claim 1, wherein,

the fluorine-containing gas is hydrogen fluoride.

3. The method of claim 1 or 2,

the window is selected from CaF₂、BaF₂、MgF₂One of LiF and ZnSe.

4. The method of any one of claims 1 to 3,

the wave number of the measurement area is 3950-4200 cm^-1。

5. A gas analyzer is a Fourier transform infrared spectrometer for measuring a fluorine-containing gas in a sample containing a corrosive gas,

the Fourier transform infrared spectrometer consists of a light source, a beam splitter, a fixed mirror, a movable mirror, a measuring chamber, a detector and an information processing device,

the detector provided is a detector with InGaAs detection elements,

the measuring chamber is provided with an inlet and an outlet for sample gas, and a single-pass gas chamber with an optical path length of 0.01-2 m,

the chamber window of the measuring chamber is made of a corrosion-resistant material,

the gas analyzer is provided with an interference unit composed of a beam splitter, a fixed mirror and a movable mirror, so that the light emitted from the light source is controlled to be 3800-14300 cm in wave number^-1The range of (a) to (b) is irradiated to the sample,

the gas analyzer is provided with an information processing device which quantitatively analyzes the fluorine-containing gas concentration based on the absorption amount of light of a predetermined wave number in the sample and a preset calibration curve.

6. The apparatus of claim 5, wherein,

the fluorine-containing gas is hydrogen fluoride.

7. The apparatus of claim 5 or 6,

the window is selected from CaF₂、BaF₂、MgF₂One of LiF and ZnSe.

8. The apparatus of any one of claims 5 to 7,

the wave number is controlled to be 3950-4200 cm^-1The sample is irradiated in the range of (1).

9. The apparatus of any one of claims 5 to 8,

when the information processing device performs fourier transform on a spectrum obtained from the absorption amount detected by the detector, a trapezoid (Trapezium) is used as an apodization function.

Technical Field

The present invention relates to a method and an apparatus for measuring and analyzing impurities in a corrosive gas and hydrogen fluoride (hereinafter, may be abbreviated as HF). More particularly, the present invention relates to a gas analysis method and apparatus for qualitatively or quantitatively measuring and analyzing impurities or hydrogen fluoride contained in a corrosive gas containing halogen atoms.

Background

As a gas for an electronic material in semiconductor production or the like, a corrosive compound containing a halogen atom in its composition is often used. It is known that impurities in a gas greatly affect the characteristics of a device and also affect a semiconductor manufacturing apparatus, and therefore, the lower the impurity concentration, the better. For example, in background section 0005 of patent document 1, it is described that a gas used in a semiconductor manufacturing process needs to be removed as much as possible of the concentration of hydrogen fluoride contained as an impurity therein.

Conventionally, measurement and analysis of trace impurities in a gas sample, for example, the quantification of impurities contained in the gas sample by only 1ppm or less, have been performed using a Fourier Transform infrared spectrometer (hereinafter, abbreviated as FT-IR) including an MCT and a TGS detector, and a long-path multiple reflection gas cell (multipass gas cell) having an optical path length of 1 to 20m in which a mirror is provided in an optical path in order to improve light absorption sensitivity. For example, patent document 2 describes a method for measuring a fluorine gas component by a fourier transform infrared spectrometer, and describes that the fluorine gas component can be measured at 4000cm^-1Hydrogen fluoride was measured nearby (table 1).

However, the method of measuring and analyzing using a long optical path multiple reflection gas cell having a mirror provided in an optical path has the following problems: when a corrosive gas sample is caused to flow through the long optical path multiple reflection gas chamber, a mirror provided in an optical path inside the gas chamber to increase the optical path length is corroded and deteriorated, sensitivity is lowered, and the gas chamber is finally unusable. In addition, in the method of patent document 2, the detection concentration of hydrogen fluoride is several tens to several thousands ppm, and a high sensitivity method of detecting 1ppm or less is not used. Non-patent document 1 describes that the detection limit of hydrogen fluoride is 12.5ppm when a single-pass (single-path) 10cm gas cell is used.

In addition to the above methods, as a method for analyzing a trace component without using a long-optical-path multiple reflection gas chamber, there is a method of removing a corrosive gas component, and when an impurity component is low in concentration, further concentrating and measuring the component. For example, patent document 3 describes the immobilization removal of F as a measure of hydrogen fluoride in a fluorine gas₂The gas was measured using a 1.5m gas cell.

However, this method requires pretreatment such as removal of corrosive gas components before measurement of the sample and, in some cases, concentration of impurity components. Therefore, there are the following problems: in measurement and analysis, many steps are required, and moreover, an error is increased by pretreatment.

Further, as a method for increasing the optical path length without using a long-optical-path multi-reflection gas cell to improve the measurement accuracy and sensitivity, a method of extending the tube length of the gas cell without adding a mirror in the gas cell and measuring the length by a so-called one-way optical path length may be considered. However, in this method, when the cell length is 1m or more, the internal volume of the cell increases, the gas purification performance decreases, and the tube length of the gas chamber increases, so that there are problems such as an increase in light attenuation, an increase in the apparatus space, and a weight increase, and thus it is not suitable for practical use.

Therefore, a method and an apparatus which can solve the above-mentioned problems and can measure and analyze impurities in a corrosive gas, particularly hydrogen fluoride, with high sensitivity without requiring pretreatment are desired.

(Prior art document)

(patent document)

Patent document 1: japanese laid-open patent publication No. 2008-214187

Patent document 2: japanese laid-open patent publication No. 2008-197120 (Table 1)

Patent document 3: japanese patent laid-open publication No. 2003-014716

(non-patent document)

Non-patent document 1: MIDAC corporation PFC Monitoring by FTIR in LCD industry, analytical background knowledge-analytical Instrument application/ft-ir gas analysis application [ average 30 years 2 months 13 days search ], Internet < URL: https:// www.kdijpn.co.jp/>

Disclosure of Invention

(problems to be solved by the invention)

The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly sensitive method and apparatus capable of measuring and analyzing impurities and hydrogen fluoride in a corrosive gas without pretreatment. More specifically, provided are a method and an apparatus which can measure a hydrogen fluoride concentration in a gas to be measured containing a corrosive gas discharged from various other manufacturing processes such as a gas manufacturing process and an electronic device manufacturing apparatus, without requiring pretreatment, thereby reducing manpower and material resources, and which can measure an accurate concentration with high sensitivity.

(measures taken to solve the problems)

The present inventors have intensively studied to solve the above problems and found that when a fluorine-containing gas in a sample containing a corrosive gas is measured by a fourier transform infrared spectrometer, a single-pass gas cell having no mirror in the optical path is used so that the corrosion does not occur even in the presence of the corrosive gas, and further, an InGaAs detector is used for high sensitivity so that the fluorine-containing gas such as hydrogen fluoride can be quantitatively analyzed with high sensitivity without pretreatment in the presence of the corrosive gas. Particularly surprisingly, it was found that a fluorine-based gas can be measured with high sensitivity even though the optical path length of a single-pass gas cell in which no mirror is present in the optical path is short. Furthermore, water (H) mixed in the sample and the inside of the apparatus was found₂O) is a method for measuring a fluorine-based gas such as hydrogen fluoride to be measured without affecting the measurement wavenumber region of the measurement, whereby the fluorine-based gas can be quantitatively analyzed with high precision, and the present invention has been completed.

That is, the present invention relates to a gas analysis method for measuring a fluorine-containing gas in a sample containing a corrosive gas by a fourier transform infrared spectrometer, wherein,

the Fourier transform infrared spectrometer comprises a detector with an InGaAs detection element and a single-path gas cell with an optical path length of 0.01-2 m,

the cell window is made of a corrosion resistant material,

the wave number of the measuring region is 3800-14300 cm^-1，

The fluorine-containing gas concentration is quantitatively analyzed from the absorption amount of light of a predetermined wave number in the sample and a preset calibration curve.

Further, the present invention relates to a method as described above, wherein the corrosive gas is fluorine (fluoride), krypton difluoride (krypton difluoride), xenon difluoride (xenon difluoride), xenon tetrafluoride (xenon tetrafluoride), xenon hexafluoride (xenon hexafluoride), chlorine monofluoride (chlorine monofluoride), chlorine trifluoride (chlorine triflouride), bromine monofluoride (bromine monofluoride), bromine trifluoride (bromine pentafluoride), iodine monofluoride (iodine fluoride), iodine tetrafluoride (iodine triflouride), iodine pentafluoride (iodine triflouride), phosphorus trifluoride (phosphorus trifluoride), phosphorus trifluoride (phosphorus difluoride), phosphorus trifluoride (fluorine trifluoride), phosphorus trifluoride (phosphorus difluoride), phosphorus trifluoride (phosphorus trifluoride), phosphorus trifluoride (fluorine trifluoride), fluorine trifluoride (fluorine fluoride), fluorine (phosphorus trifluoride), fluorine (fluorine fluoride), fluorine (fluoride), fluorine (fluorine), fluorine (fluorine), fluorine (fluorine) and fluorine (fluorine) fluoride), fluorine (fluorine) fluoride), fluorine (fluorine) and fluorine (fluorine) compound), fluorine (fluorine) and fluorine (fluorine) in), fluorine (fluorine, Vanadium pentafluoride (vanadiumpentafluoride), molybdenum hexafluoride (molybdenum hexafluoride), uranium hexafluoride (uranium hexafluoride), rhenium hexafluoride (rheum hexafluoride), rhenium heptafluoride (rheum heptafluoride), osmium hexafluoride (osmium hexafluoride), iridium hexafluoride (iridium hexafluoride), platinum hexafluoride (platinum hexafluoride), tungsten hexafluoride (tungsten hexafluoride), nitrosylfluorine (nitroxyl fluoride), nitrosylfluorine (nitrosylfluorine), nitroylfluorine (carbonoylfluorine), fluoromethylfluorine (monofluoromethyl fluoride), methacryloylfluorine (fluoroacetyl fluoride), fluorofluoromethylacethylfluorine (fluoromethylacethyl fluoride), fluoromethylacethylfluoroform (fluoroacetyl fluoride), fluoroform (fluoroform fluoride), fluoroform fluoride (fluoroform fluoride) and the like.

Further, the fluorine-based gas is preferably hydrogen fluoride.

Still further, the present invention relates to the above method wherein the window is a corrosion resistant material. For example, CaF₂、BaF₂、MgF₂One selected from among LiF and ZnSe, among these materials, CaF is preferable₂。

Furthermore, the invention relates to a measurement area with wave number of 3950-4200 cm^-1The above method of (1).

The present invention also relates to a gas analyzer which is a fourier transform infrared spectrometer for measuring a fluorine-containing gas in a sample containing a corrosive gas, wherein,

the Fourier transform infrared spectrometer consists of a light source, a beam splitter, a fixed mirror, a movable mirror, a measuring chamber (cell), a detector and an information processing device,

the detector provided is a detector with InGaAs detection elements,

the measuring chamber is provided with an inlet and an outlet for sample gas, and a single-pass gas chamber with an optical path length of 0.01 m-2 m,

the chamber window of the measuring chamber is made of a corrosion-resistant material,

the gas analyzer includes an interference unit composed of a beam splitter, a fixed mirror and a movable mirror, so that the light emitted from the light source is controlled to have a wave number of 3800-14300 cm^-1The range of (a) to (b) is irradiated to the sample,

the gas analyzer includes an information processing device for quantitatively analyzing a fluorine-containing gas concentration based on an absorption amount of light of a predetermined wave number in the sample and a preset calibration curve.

Further, the present invention relates to the above-mentioned apparatus wherein the corrosive gas is tungsten hexafluoride and the fluorine-based gas is hydrogen fluoride.

Still further, the present invention relates to the above-described device wherein the window is of a corrosion resistant material. For example, CaF₂、BaF₂、MgF₂One selected from among LiF and ZnSe, among these materials, CaF is preferable₂。

Further, the present invention relates to the wave number of 3950 to 4200cm^-1The above-mentioned device for irradiating a sample.

Further, the present invention relates to the above-mentioned apparatus using a trapezoid (Trapezium) as an Apodization (Apodization) function when the information processing apparatus performs fourier transform on a spectrum obtained from the absorption amount detected by the probe.

Hereinafter, the present invention will be described in detail using appropriate drawings.

The gas analysis method and the gas analysis apparatus of the present invention are a method and an apparatus for measuring a fluorine-containing gas in a sample containing a corrosive gas by a fourier transform infrared spectrometer.

Fig. 1 is a diagram showing the structure of a fourier transform infrared spectrometer 1 used in the present invention. Referring to fig. 1, the present invention includes: a light source 2 configured to emit parallel light; an interference unit that outputs light (typically, infrared light) from the light source 2 by interference; a measurement cell (cell)6 in which a sample or the like is housed and is irradiated with light from the light source 2 by an interference unit; and a detector 7 that receives light that has passed through the measurement chamber 6. The interference unit is composed of a fixed mirror 5, a beam splitter 3, and a movable mirror 4 that is moved in parallel in, for example, the XY directions by a drive unit not shown.

The information processing device 8 is a general-purpose or special-purpose computer including a CPU, a memory, an input/output interface, an AD converter, and the like, and can perform information processing and printing on a printer by causing the CPU, an external device, and the like to cooperate with each other in accordance with a predetermined program stored in a predetermined area of the memory.

As an information processing method of the information processing device 8, in the present invention, the absorption spectrum of a measurement object, for example, hydrogen fluoride, in a measurement sample detected by the probe 7 is compared with a baseline (baseline) obtained by background (background) measurement using only an inert gas such as nitrogen, and then the measurement object is subjected to fourier transform to perform information processing. When the information processing device 8 performs fourier transform, a trapezoid (Trapezium) can be used as the apodization function.

In fig. 4, baseline waveforms based on different apodization functions are depicted for the same baseline. In FIG. 4, the horizontal axis (X axis) is the wave number (in cm)^-1) The vertical axis (Y axis) represents absorbance. In fig. 4, as is clear from the base lines obtained by using the respective functions of Triangle (32), trapezoid (31), and Cosine (33), the use of trapezoid (31) makes it possible to improve the peak intensity, i.e., the peak of the absorption spectrum of hydrogen fluoride, more sharply than the other functions, that is, to improve the peak intensity, and is also suitable for the quantification of fluorine-based gas.

In the measurement by the fourier transform infrared spectrometer 1, the method of confirming the peak ascribed to hydrogen fluoride is: when the peak has the same wave number and the same shape as the spectrum of the standard gas of hydrogen fluoride, it is determined to be the peak of hydrogen fluoride. The peak digitizing method can be calculated by specifying "a peak attributed to hydrogen fluoride" and "a noise peak other than hydrogen fluoride" using a "peak height" program on software used for the information processing apparatus 8. Peaks located adjacent to the peak ascribed to hydrogen fluoride are noise, and the "noise peak height" may be calculated using the top and bottom edges of each noise peak closest to the left and right of the peak ascribed to hydrogen fluoride, or the signal-to-noise ratio (S/N ratio) may be calculated as the "height ratio".

FIG. 5 is a spectrum of a standard cone gas (hydrogen fluoride concentration of 13.4ppm) obtained by diluting hydrogen fluoride with nitrogen. The upper part of fig. 5 is the result when a detector with InGaAs detecting elements is used under the condition of accumulating 50 times,the lower part is the result when the detector with MCT detecting elements is used in a total of 128 times. The horizontal axis (X axis) is the wave number (in cm)^-1) The vertical axis (Y axis) represents absorbance. Although there is a reason why the detecting element is different, as shown in FIG. 2, the absorption spectrum of hydrogen fluoride is 3550 to 4300cm in wave number^-1Has a plurality of peaks. Therefore, in order to quantify hydrogen fluoride, it is preferable to select 4075cm having the highest peak^-1The wave number of (2) was used for quantification. Further, FIG. 2 shows absorption spectrum data obtained by a Fourier transform infrared spectrometer, and is data of "JP mechanical society, proceedings B, volume 70 (2004), volume 692, p 1058-1063".

The wave number is selected in such a case that water may be mixed in the sample and hydrogen fluoride is quantified. Therefore, the wave number of the impurity components except water is 3550-4300 cm^-1When the range (b) has absorption or when fluorine-based gas other than hydrogen fluoride is measured, the wave number or the range thereof for quantitative determination can be appropriately selected.

Fig. 6 is a calibration curve obtained by using a standard gas obtained by diluting hydrogen fluoride with nitrogen. The horizontal axis (X axis) represents the concentration of hydrogen fluoride, and represents the concentration of 0.47 to 4.71 ppm. The determination of these concentrations of hydrogen fluoride using the Fourier transform Infrared spectrometer of the invention will be at 4075cm^-1The absorption amount at the wave number is represented on the vertical axis (Y axis) as absorbance. By using this calibration curve, the concentration of hydrogen fluoride can be calculated by obtaining the absorbance of hydrogen fluoride in a sample having an unknown concentration. That is, the fluorine-containing gas concentration can be quantified by using light of a predetermined wave number, based on the absorption amount of the measurement pattern and a preset calibration curve.

In the measurement of the concentration of hydrogen fluoride based on this calibration curve, when the data of the calibration curve is input to the information processing device 8 in fig. 1 in advance, the concentration of hydrogen fluoride can be calculated from the absorbance obtained by measuring the sample. Further, as a method for creating the calibration curve, linear regression may be performed by simply connecting points indicating the hydrogen fluoride concentration and the absorbance by straight lines (for example, points indicated by black dots in fig. 6), or by using the least square method, or a better fitting may be performed by a general method, for example, by using a quadratic function or a higher-order function. Further, a concentration region having a good correlation between the concentration and the absorbance of the measurement target can be weighted by numerical weighting or the like.

The fourier transform infrared spectrometer used in the present invention must use a detector with InGaAs detection elements with high sensitivity. As described in the examples shown below, when a detector having an MCT detection element and a TGS detection element is used, the detection sensitivity (concentration that can be quantified) is insufficient, and therefore, it is necessary to use a fourier transform infrared spectrometer equipped with a detector having an InGaAs detection element that can achieve higher sensitivity.

The gas chamber arranged on the Fourier transform infrared spectrometer can be a one-way gas chamber with the optical path length of 0.01 m-2 m. More preferably, the optical path length may be 0.1m to 1 m. In order to ensure that the measurement can be performed, the optical path length may be appropriately determined according to the amount or concentration of the measurement target contained in the corrosive gas. Generally, the length may be determined in consideration of the size of the spectrometer, the measurement location, and the like.

Here, in the present invention, the reason why the gas cell provided in the fourier transform infrared spectrometer is defined as the single-pass gas cell having an optical path length of 0.01m to 2m is that in the long-optical-path gas cell having a mirror in the gas cell, the mirror is corroded by the corrosive gas, and appropriate measurement cannot be performed.

Fig. 3A shows a schematic diagram relating to a long optical path gas cell 10, and fig. 3B shows a schematic diagram relating to a single path gas cell 20.

In the long optical path gas cell 10, light incident through the reflecting mirror 11 is reflected a plurality of times by the reflecting mirror 11 as indicated by an arrow, and during this time, the light is absorbed by the compound to be measured in the gas cell 12, and the amount of light absorption until the light is received by the detector can be increased or enlarged. The detection sensitivity is improved by such a mechanism. However, if a corrosive gas, for example, a halogen gas such as tungsten hexafluoride, is present in the gas chamber, the mirror is corroded by the corrosive action, and the mirror does not operate normally, and as a result, improvement of the measurement sensitivity cannot be expected.

On the other hand, in the single-pass gas cell 20, no mirror is present in the gas cell 21. When a sample is measured, the measurement sample is introduced into the gas chamber 21 through the gas inlet 22 (or 23), and after measurement, the sample is discharged through the gas outlet 23 (or 22). The measurement sample remains in the gas cell, absorbing only the incident light and being received by the detector. That is, in the single-pass gas cell 20, since no mirror is present in the gas cell 21, light is absorbed only by a single pass. Therefore, since the light absorption amount of the object to be measured cannot be increased or amplified as in the case of a long optical path gas cell, it is necessary to increase the sensitivity of the detector, and therefore, it is significant to use a detector having an InGaAs detecting element with high sensitivity in the present invention.

The single-pass gas chamber 20 shown in fig. 3B has a cylindrical shape, and infrared chamber windows (not shown) are provided at both ends. With respect to the fourier transform infrared spectrometer 1 (fig. 1), a sample containing a corrosive gas is flowed into the single-pass gas cell 20, and the amount of light reduction of infrared rays transmitted through the single-pass gas cell 20 is measured to measure the concentration of a fluorine-containing gas in the sample gas. It is preferable to use a corrosion-resistant material, such as calcium fluoride (CaF), which does not corrode the chamber window (not shown) for transmitting infrared rays through the inside of the gas chamber, by the same corrosive gas as described for the above-mentioned reflecting mirror₂) Thereby forming the structure.

In the single-pass gas chamber 20 of fig. 3B, a sample containing a corrosive gas can be introduced into the single-pass gas chamber 20 from the gas inlet 22 (or 23) directly from the production process or various processes, and used for process analysis.

Further, a heater (not shown) such as a band heater or a cooler (not shown) may be attached to the outer periphery of the single-pass gas chamber 20 so as to maintain the gas inside the single-pass gas chamber 20 at a predetermined temperature.

In the invention, the measuring region is 3800-14300 cm in wave number^-1More preferably 3950 to 4200cm^-1The range of (1). However, in fig. 1, the beam splitter 3, the fixed mirror 5, and the movable mirror are used from the light source 1 as long as the provided interference unit permitsThe light generated by the interference unit of 4 may be light of any wave number, and generally speaking, the wave number may be any wave number that can be used for a fourier transform infrared spectrometer. Therefore, the measurement region as referred to herein is a region that can cover the number of light absorption waves of the substance or compound to be measured in the present invention.

For example, in the case of hydrogen fluoride, as can be seen from FIG. 2, the wave number is 3950 to 4200cm^-1The above range may be used. The reason is as follows: when water is mixed in the measurement sample, the wave number of the hydrogen fluoride can be 3600-3950 cm^-1The range of (a) is seen as absorption, and therefore there is a risk of hindering the measurement of hydrogen fluoride.

In the present invention, when a fluorine-based gas other than hydrogen fluoride is measured in a sample containing a corrosive gas, the wave number of light used for appropriate measurement may be set in consideration of each component contained in the sample to be measured.

(Effect of the invention)

According to the present invention, a highly sensitive method capable of measuring and analyzing impurities and hydrogen fluoride in a corrosive gas without requiring pretreatment can be provided.

According to the present invention, it is possible to provide an analyzer for fluorine-based gas which does not require pretreatment, has high sensitivity, and is less susceptible to corrosive gases.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a fourier transform infrared spectrometer in a gas analysis apparatus according to an embodiment of the present invention.

FIG. 2 shows absorption spectra data obtained by Fourier transform infrared spectroscopy for various compounds.

Fig. 3A is a diagram showing a schematic structure of a long optical path multiple reflection gas cell in a fourier transform infrared spectrometer.

FIG. 3B is a diagram showing a schematic structure of a single pass gas cell in a Fourier transform infrared spectrometer.

Fig. 4 is a graph depicting baseline waveforms based on different apodization functions for the same baseline correlation for absorption spectrum data obtained using a fourier transform infrared spectrometer.

FIG. 5 is a spectrum of a standard cone gas (hydrogen fluoride concentration: 13.4ppm) obtained by diluting hydrogen fluoride with nitrogen.

Fig. 6 is a calibration curve obtained using a standard gas obtained by diluting hydrogen fluoride with nitrogen.

Fig. 7 is a graph showing a spectrum of hydrogen fluoride in tungsten hexafluoride in example three.

Detailed Description

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.