JPH1183737A - Method and instrument for measuring infrared reflectance spectrum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring infrared reflectance spectrum using a rotary polarizer which is interlocked with a Fourier transform infrared spectroscope, so as to separate the infrared absorption by a surface elements from that by a gaseous phase and an instrument used for the method. SOLUTION: In a method for measuring infrared reflectance spectrum, a polarizer 4 is rotated synchronously to the scanning of a Fourier transform infrared spectral interferometer 7 at the time of starting the measurement of infrared reflectance spectra, and the spectra of p-polarized light and s-polarized light are alternately integrated synchronously to the rotation of the polarizer 4. Then, the infrared reflectance absorption by a surface species adsorbed to the surface of a sample composed of a metal single crystal 12, by calculating the ratio between the spectra of the p-polarized light and s-polarized light and offsetting the absorption band of gaseous phase molecules.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring an infrared reflection spectrum using a rotating polarizer.

[0002]

2. Description of the Related Art In recent years, with the breakthrough of surface analysis, research on chemical reactions on a metal single crystal surface has progressed.
The structures and properties of various adsorbed species and reaction intermediates have been elucidated. However, it is unclear whether the findings found using these ultrahigh vacuum devices are directly related to the surface state under normal pressure.

[0003] In particular, the catalytic action of a solid surface often occurs in the presence of molecules in the gas phase, and the observation of the surface species adsorbed irreversibly at low temperatures under vacuum can explain the whole effect. Have difficulty. Spectroscopy using light is effective for analyzing surfaces exposed to pressures from ultra-high vacuum to normal pressure.

[0004] Electron-based techniques often used as surface analysis methods, such as high-resolution electron beam energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), and vacuum ultraviolet photoelectron spectroscopy (UPS), are known. Since a high vacuum is required to make electrons fly, measurement under high pressure is in principle impossible. In recent years, with the development of the scanning probe microscope (SPM), it has become possible to observe the surface under various conditions. The surface species that can be observed by the SPM are those whose surface movement is restricted. limited.

Further, vibration spectroscopy gives much knowledge to the structure of surface adsorbed species, but vibration spectroscopy using light applicable to molecules adsorbed on the surface of a metal single crystal includes infrared reflection absorption spectroscopy. Spectroscopy (IRAS), Interface Sum Frequency Generation (SF
G) are the two main methods. IR mentioned above
AS is a highly sensitive Fourier transform infrared spectrometer (FTIR)
With the spread of, it has come to be widely used as a simple and convenient method for extracting a lot of surface information.

[0006]

However, in the above-mentioned IRAS, it is necessary to detect weak absorption by surface adsorbed species. Ingenuity is required. In addition, the above-mentioned SFG is a non-linear laser spectroscopy that has been developed very recently, and its application to surface analysis under pressures from ultra-high vacuum to normal pressure has been reported. Applications are limited due to being limited by the type of device and because the device is expensive and special.

[0007] The present invention eliminates the above problems and, in order to separate the absorption by surface species from the infrared absorption by the gas phase, uses a rotating polarizer in which a polarizer is linked to a Fourier transform infrared spectrometer. It is an object of the present invention to provide a method and an apparatus for measuring an external reflection spectrum.

[0008]

According to the present invention, there is provided a method for measuring an infrared reflection spectrum, comprising the steps of: rotating a polarizer in synchronization with scanning by a Fourier transform infrared spectroscopic interferometer; In synchronism with this rotation, the spectra of p-polarized light and s-polarized light are alternately integrated, the ratio is taken, the absorption band of gas phase molecules is canceled out, and infrared reflection absorption by the surface species adsorbed on the metal surface is performed. The spectrum is obtained.

[2] The method for measuring an infrared reflection spectrum according to the above [1], wherein the atmosphere temperature and pressure on the metal surface can be adjusted. [3] In the method for measuring an infrared reflection spectrum according to the above [1], the metal surface is a metal single crystal surface. [4] The method for measuring an infrared reflection spectrum according to the above [3], wherein the metal single crystal surface is a Pt (111) surface and the Pt (111) surface is present in the presence of 10 ³ Pa of ethylene.
The spectrum of ethylene adsorbed on the (111) surface is measured.

[5] The method for measuring an infrared reflection spectrum according to the above [3], wherein the surface of the metal single crystal is Pt (1
11) On the surface, the spectrum of ethylene adsorbed on the Pt (111) surface is measured in the presence of ethylene in a 150K temperature atmosphere. [6] In an infrared reflection spectrum measuring device, a spectroscopic device for rotating a polarizer in synchronization with scanning of a Fourier transform infrared spectroscopic interferometer, and a metal sample attached to the spectroscopic device are set and large. A vacuum device capable of setting a pressure close to the atmospheric pressure and a detector for detecting an infrared reflection absorption spectrum are provided.

[7] In the infrared reflection spectrum measuring apparatus according to the above [6], the vacuum apparatus is provided with a small cell having a short optical path length in order to reduce absorption of gas phase molecules. . [8] The apparatus for measuring an infrared reflection spectrum according to the above [6], further comprising means for adjusting the ambient temperature and pressure of the metal sample.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention provides an IRAS (Infrared Reflection Absorption Spectroscopy) device for directly observing the surface of a metal single crystal placed in a gas at a pressure from ultra-high vacuum to near normal pressure, and an ultra-high-intensity device equipped with a small cell. A vacuum device,
And a detector for detecting an infrared reflection absorption spectrum.

The behavior of equilibrium adsorption of ethylene obtained by using the apparatus of the present invention will also be described later. First, the FTIRAS method using a synchronous rotation polarizer will be described.
In order to apply IRAS under conditions where infrared absorption by the gas phase is present, it is important how to offset the absorption by the gas phase well and extract only the surface area. In particular, the absorption by the surface species is only about 0.1 to 1% as a change in reflectance, and various modulation methods for detecting this change have been developed.

The infrared absorption by the surface species on the metal surface is limited by the surface selection rule. According to this, incident p-polarized infrared light interacts with reflected light at the surface to create a strong oscillating electric field in the surface normal direction, interacting with the surface normal component of the transition dipole moment of the vibration of the adsorbed species, Absorb this light. On the other hand, for the s-polarized light, the electric field due to the incident light is offset by the reflected light at the surface, so that absorption by the surface adsorbed species does not appear. Since the molecules in the gas phase are isotropically oriented, they absorb light of any polarization in the same way. Therefore, taking the ratio of the spectra obtained with p-polarized light and s-polarized light, Is canceled, and only the absorption by the surface area can be extracted.

When the spectra using each polarized light are measured separately, it is difficult to completely remove the influence of the gas phase due to disturbances such as minute changes in the pressure and composition of the gas phase and temperature changes. Therefore, measurement using the modulation method is considered to be effective. In order to modulate polarization, a method of mechanically switching polarization, a method of using a photoelastic modulator (PEM), and the like are used. Any of the above methods can be applied to a spectrometer using a diffraction grating.
A spectroscopic device using IR requires high-frequency modulation by a PEM (photoelastic modulator) device to avoid overlapping with the modulation frequency of the FTIR interferometer.

However, the above-mentioned PEM device is not only expensive, but also modulates at a high frequency (around 150 kHz).
It is not easy to obtain high sensitivity. Further, in the PEM device, the wavelength that can be modulated is limited, and one of the problems is that a good spectrum cannot be obtained in the entire infrared region.

In recent years, not only demodulation using a conventional lock-in amplifier, but also methods using various electric circuits have been proposed. In the field of electrochemistry, IRAS is one of the important analytical methods for understanding the structure of adsorbed species on the surface of a metal electrode. Because of the presence of a layer of solution on the surface of the sample used in electrochemistry, it may be even more difficult to extract the absorption of the surface species from this absorption. By changing the electrode potential on the electrode surface, only the surface adsorbed species can be reversibly changed, and a potential modulation method utilizing this is used.

In particular, recently, the SNIFTIRS method (Su) in which the potentials are alternately changed in synchronization with the FTIR interferometer and the spectra at the two electrode potentials are alternately acquired.
bfraction Normalized Inte
rfaced FTIR Spectroscopy)
Is often used. According to this method, spectra at two electrode potentials are alternately measured in a short time, so that it is hardly affected by a change in environment and a good spectrum can be obtained. However, the subject is limited to observing surface species that reversibly change to fluctuating potentials at the electrode surface in the electrolyte solution.

At the gas / solid interface, in the same manner as in the SNIFTIRS method, the switching of the polarization is synchronized with the scan of the FTIR interferometer, and the spectra of the s-polarized light and the p-polarized light are measured alternately. It is considered that if the spectrum of the interface is obtained from the ratio, a good spectrum which is less affected by the temporal change of the pressure and the composition of the gas phase can be obtained.

The present invention provides a SNIFTI for modulating polarization.
Although it can be interpreted as the RS method, unlike the method that modulates the electrode potential, not only the electrode surface, but also in a vacuum, in the presence of a gas phase,
Applicable to any metallic material in solution.
Further, since the sample is not observed by directly changing the sample as in the SNIFTIRS method, nondestructive observation is possible even for an adsorbed species whose chemical behavior on the surface is unknown.

The details of a spectroscopic apparatus that rotates the polarized light in synchronization with the scan of the FTIR interferometer and a vacuum apparatus that can be used up to a pressure near the atmospheric pressure will be described below. [1] FTIR spectrometer JFT10 manufactured by JEOL Ltd.
A type 0 FTIR spectrophotometer was used. Since the FTIR interferometer uses an air bearing and ejects a large amount of compressed air into the apparatus, it is difficult to handle the apparatus by replacing the inside of the apparatus with nitrogen gas. In addition, the influence of absorption bands of water vapor and carbon dioxide in the atmosphere is also a major problem.

FIG. 1 is a plan view of an IRAS measuring device showing an embodiment of the present invention, and FIG. 2 is a schematic diagram of a wire grid type rotating polarizer driven by a stepping motor of the IRAS measuring device showing an embodiment of the present invention. FIG. 2A is a side view of the rotating polarizer (including an attached control device), and FIG.
(B) is a front view of the rotating polarizer. In FIG. 1, reference numeral 2 denotes an IR for directly observing the surface of a metal single crystal placed in a gas at a pressure ranging from ultra-high vacuum to near normal pressure.
An AS (Infrared Reflection Absorption Spectroscopy) device, 1 is this IRA
Attached to the S device 2, the sample 12 is set,
An ultra-high vacuum apparatus equipped with a small cell, 13 is a semiconductor detector composed of an InSb / MCT type (indium antimony / mercury cadmium tellurium) for detecting an infrared reflection absorption spectrum.

The IRAS (Infrared Reflection Absorption Spectroscopy) device 2 extracts a glow light source 5 made of a material mainly composed of SiC that generates infrared light, and extracts only light of a required wavelength from the glow light source 5. An optical filter 6, an interferometer 7, which is a device for scanning the movable mirror to the left and right to modulate infrared light, and a He- for measuring the position of the interferometer 7;
It has a Ne laser 8 and a rotating polarizer (wire grid polarizer) 4 described later. In addition, He-Ne laser 8
Is also used as a guide light for optical adjustment.

Therefore, each of the rotating polarizer 4, the interferometer 7, the semiconductor detector 13, and the means for adjusting the temperature and pressure of the sample in the ultra-high vacuum vessel 11 is connected to the electronic control unit 15, and Control is possible. As described above, the sample chamber is provided with an attachment for extracting external parallel light. As shown in FIG. 2, a wire grid polarizer (rotating polarizer) 4 whose rotation can be controlled by a stepping motor 3 is provided here. 4A is a first timing gear, 4B is a timing belt, and 4C is a second timing gear.

A signal for rotating the rotating polarizer 4 is taken out from a terminal for an automatic sample exchange attachment of the FTIR, and is synchronized with the operation of the interferometer 7 as shown in FIG. 90 ° by the electronic control unit 15
Each rotation can be done. Since the rotation can be controlled on existing measurement software, the measurement operation can be performed in the same manner as a normal FTIR measurement. From this measurement software, the rotating polarizer 4 can be rotated every arbitrary number of scans from every one scan to every 100 scans, and integration can be alternately repeated.

In FIG. 2A, the electronic control unit 15 includes a CPU (central processing unit) 16, a memory 17, a display unit 18, an interface (I / F) circuit 19, and the like. Then, the infrared light that has passed through the rotating polarizer 4 is condensed by a parabolic mirror on the surface of the sample 12 in the ultrahigh vacuum apparatus 1 at an incident angle of 84 °, and the reflected light passes through two parabolic mirrors. After that, the light is focused on the InSb / MCT semiconductor detector 13.

[2] Ultra-high vacuum apparatus FIG. 3 is a side view of an ultra-high vacuum apparatus of an IRAS measuring apparatus showing an embodiment of the present invention. This ultra-high vacuum device 1 includes two vacuum vessels. The upper container is a sample pretreatment container 21 capable of performing sample pretreatment, Auger electron spectroscopy, low-speed electron diffraction measurement, and temperature programmed desorption measurement. An oil diffusion pump (Edwards. EO-4) 46 And liquid nitrogen trap (Vacuum Generators, CCT)
(−100) 47, it is constantly evacuated to an ultra-high vacuum of 10 ⁻⁸ Pa or less.

The lower container is an IRAS measuring container 31. As shown in FIG. 4, an infrared window 32 is provided. This is because O using differential exhaust (differential exhaust port 35)
Since the window material is fixed with a ring seal and the window material can be replaced, the infrared window 32 can be selected according to the purpose. Usually, BaF ₂ or NaCl is used. In FIG. 3, reference numeral 49 denotes a closed circulation reactor.

Hereinafter, the fixing of the infrared window will be described. FIG. 4 is a schematic view of a portion for fixing an infrared window material to an ultrahigh vacuum device of an IRAS measuring device showing an embodiment of the present invention. In the ultrahigh vacuum device 1, an O-ring 3
If 3 exists, the leakage cannot be ignored, so the O-ring 33 is doubled to provide a sub exhaust chamber to reduce the amount of leakage.

As shown in FIG. 4, the infrared window 32 is fixed to the conflat flange 34 by an O-ring (made of Viton) 33, and the sub exhaust chamber is evacuated by the oil rotary pump 40 so that the inside of the ultra-high vacuum device 1 is Prevents air from leaking into As shown in FIG. 5, the lower vessel is independently provided with a turbo molecular pump (ULVA) by a gate valve independently of the upper vessel.
C, UTM-150) 36 to evacuate to an ultra-high vacuum region. The sample 12 is moved between the upper container (the sample pretreatment container 21) and the lower container (the IRAS measurement container 31) by the manipulator 37 (see FIG. 3) attached above. When the sample 12 is in the lower container, A flange attached to the sample holder 48 provides isolation between the upper and lower vessels.

For measurement under a pressure of several hundred Pa or more,
A small cell 38 installed in the lower container is used.
Next, the ultra-high vacuum device will be described in detail. FIG.
FIG. 1 is a schematic view of a small cell mounted in an ultrahigh vacuum vessel of an IRAS measuring device and a peripheral portion thereof showing an embodiment of the present invention.

As shown in FIG. 5, by pressing the small cell 38 located in the lower container against the sample holder 48 by the linear introducer 39, it becomes possible to introduce gas only into the small cell 38. Even if a gas at about atmospheric pressure is introduced into the small cell 38, the pressure in the lower container is 10 ⁻⁶ Pa or less. An infrared window 41 having an O-ring 42 is also attached to the small cell 38, and even when the small cell 38 is covered (the small cell 38 is raised from the state of FIG. 5 and covered with the sample holder 48), The sample 12 is configured so as not to hinder the IRAS measurement. In addition, small cell 3
The volume in the chamber 8 is about 50 cm ³ , and the composition of the gas in the chamber 8 is configured to be introduced into a mass analyzer and analyzed.

The sample gas is supplied to a closed circulation reactor 49.
And introduced into the small cell 38. Further, the metal single crystal sample 12 is fixed to a sample holder 48 which can be cooled using a Ta wire having a diameter of 0.3 mm, and the temperature of the sample 12 can be controlled by supplying electricity to the sample. When cooling to low temperature, the sample holder 4
A cold nitrogen gas whose temperature is controlled is circulated through 8. Also,
In a region where the pressure is high, the sample gas condenses on the surface of the sample holder 48. Therefore, it is important to control the sample holder 48 to a temperature at which it does not condense. In FIG. 5, reference numeral 43 denotes a gate valve, 44 denotes a refrigerant reservoir, and 45 denotes an O-ring.

Hereinafter, the performance of the device of the present invention will be described as C ₂ H ₄ / P
Confirm by applying t (111) to research. Pt
The study of ethylene adsorbed on the (111) surface is described as an example of the application of the apparatus of the present invention. The adsorption behavior of ethylene on the Pt (111) surface has been studied under ultra-high vacuum by many researchers for a long time, but the adsorption state in the presence of a gas phase or during a reaction such as hydrogenation has been studied. ,
At present, it has not been clarified yet.

In recent years, the present inventors and the group of Somorjay et al. Have revealed that when gaseous ethylene is present, new adsorbed species are observed on the surface, and it is important to consider catalytic reactions such as hydrogenation of ethylene. It is a great finding. Hereinafter, the procedure for measuring the IRAS spectrum will be described. (1) First, a Pt single crystal is set in the sample pretreatment container 21.

(2) Next, the surface of the Pt single crystal is cleaned by argon ion etching, and the cleanliness is confirmed by electron spectroscopy. (3) Next, the sample 12 is transferred to the IRAS measurement container 31. (4) Next, the small cell 38 is set on the sample 12, the Ta line of the sample holder 48 is energized to adjust the temperature of the sample 12, and a sample gas of a predetermined pressure is introduced into the small cell 38.

FIG. 6 is a diagram showing an IRAS spectrum measured with p-polarized light and s-polarized light by introducing 1.3 × 10 ³ Pa of ethylene into a small cell of the IRAS measuring apparatus showing the embodiment of the present invention. Note that both spectra are P under vacuum.
The ratio to the spectrum of t (111) is taken. In both spectra, the absorption of several percent in reflectance change is 31%.
06,2989,1444,949cm ^-1 , which are attributed to the CH inverse symmetry stretching, CH symmetry stretching, CH ₂ pinching deformation, and out-of-plane bending vibration of ethylene molecules in the gas phase. Is done.

It is difficult to find the absorption of the surface species directly from these spectra, and it is apparent that it is essential to take the ratio between the spectra of p-polarized light and s-polarized light to cancel the absorption of gas phase molecules. FIG. 7 shows the ratio between the spectra of the p-polarized light and the s-polarized light. In other words, FIG. 7 shows an embodiment of the present invention.
It is a figure which shows the ratio spectrum of p-polarized light and s-polarized light when ethylene of 10 < ³ > Pa is introduced.

The spectrum a is obtained by integrating the spectra of the p-polarized light and the s-polarized light (1024 scans) and then measuring them separately, and taking the ratio. The spectrum b is a polarized light every 16 scans using a rotating polarizer. Are switched, and each is integrated for 1024 scans. In the case where the spectra of p-polarized light and s-polarized light were separately obtained, 235
At 0,1600,949 cm ^-1 , absorption having a rotation band peculiar to gas phase molecules was observed. These are attributed to absorption by carbon dioxide gas in the atmosphere (OCO antisymmetric stretching vibration), water vapor (HOH bending vibration), and ethylene in the cell (out-of-plane bending vibration). .

These absorptions should be canceled out by taking a ratio, but it is considered that they remain due to the fluctuation of the gas phase pressure due to the difference in measurement time. In the spectrum using the rotating polarizer, since each polarized light is switched in a short time, the absorption by these gas phase molecules is weak, and 954 is newly added.
It can be confirmed that there is a weak absorption peak at cm ^-1 .

This absorption peak is appropriate to be attributed to the surface adsorbed species because the wave number is different from that of the ethylene molecule in the gas phase and the dependency on pressure and temperature is observed as described later. This absorption peak was attributed to out-of-plane bending vibration of π-type ethylene adsorbed parallel to the surface. It can be seen that the intensity of this absorption peak has a reflectance change of about 0.1%, which is very weak as compared with the absorption by gas phase molecules shown in FIG.

FIG. 8 shows pressure and temperature changes of spectra obtained every 16 scans using a rotating polarizer. That is,
FIG. 8 is a diagram showing the pressure and temperature dependence of the IRAS spectrum when ethylene is introduced into the Pt (111) surface, showing the example of the present invention. The intensity of the absorption peak observed at 954 cm ^-1 increases with increasing ethylene pressure,
In addition, it was found that the adsorbed species was reversibly equilibrium-adsorbed because it decreased with increasing temperature.

At 2910 cm ^-1 , a broad absorption peak which is not affected by ethylene pressure or temperature is observed. This is due to the fact that irreversibly adsorbed di-σ type ethylene which has been found for a long time under ultra-high vacuum. This is due to the C · H symmetrical stretching vibration. Figure 8 shows the structures of the two types of adsorbed species observed.
As shown in FIG. Thus, equilibrium-adsorbed π-type ethylene is observed in addition to di-σ-type ethylene observed under ultra-high vacuum, and the reactivity and surface reaction of π-type ethylene in the presence of gas phase pressure are considered. The effect is clear.

As described above, according to the present invention, the polarizer is rotated in synchronization with the scanning of the FTIR interferometer, the spectra of p-polarized light and s-polarized light are alternately integrated, and the ratio is obtained. As a result, the absorption bands of the gas phase molecules were canceled out, and an IRAS spectrum by the surface species adsorbed at equilibrium could be obtained. In order to reduce the absorption of gas-phase molecules, an ultra-high vacuum device equipped with a small cell having a short optical path was provided.

[0045] As a model case for confirming the performance of these devices were measured spectra of ethylene adsorbed on Pt (111) surface in the presence of ethylene 10 ³ Pa. In this method, the effect of the infrared absorption band of air and gaseous ethylene is well offset, the spectrum is given by the surface species, and only the di-σ type ethylene known in experiments under the conventional ultra-high vacuum is used. Without equilibrium adsorption
It was revealed that ethylene was present on the surface.

Therefore, according to the present invention, the method using a rotating polarizer is simple, and not only under the conditions where gas phase molecules are present, but also under the IRAS observation under ultra-high vacuum. Effective for removing absorption. It can also be used for measuring liquid / solid interfaces and is expected to be widely applied in various fields. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0047]

As described above, according to the present invention, the following effects can be obtained. (A) According to the first or sixth aspect of the invention, the polarizer is F
By rotating in synchronism with the scanning of the TIR interferometer and alternately integrating the spectra of p-polarized light and s-polarized light, the absorption bands of gas phase molecules are canceled out, and an IRAS spectrum is obtained by the surface species adsorbed in equilibrium. be able to.

(B) According to the second, third or eighth aspect of the invention, highly reliable measurement of the IRAS spectrum can be performed by adjusting the atmosphere on the sample surface. (C) According to the invention of claim 4 or 5, the effect of the infrared absorption band of air or gaseous phase ethylene is favorably offset,
An IRAS spectrum based on the Pt surface species can be obtained.

(D) According to the invention of claim 7, the optical path length can be shortened in order to reduce the absorption of gas phase molecules, and an accurate IRAS spectrum by the surface species can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of an IRAS measuring apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic view of a wire grid polarizer driven by a stepping motor of an IRAS measuring apparatus showing an embodiment of the present invention.

FIG. 3 is a side view of an ultrahigh vacuum device of the IRAS measuring device showing an embodiment of the present invention.

FIG. 4 is a schematic view of a portion for fixing an infrared window material to an ultrahigh vacuum device of an IRAS measuring device according to an embodiment of the present invention.

FIG. 5 is a schematic view of a small cell mounted in an ultrahigh vacuum vessel of an IRAS measuring device and a peripheral portion thereof according to an embodiment of the present invention.

FIG. 6 is a diagram showing an IRAS spectrum measured with p-polarized light and s-polarized light by introducing 1.3 × 10 ³ Pa of ethylene into a small cell of the IRAS measuring apparatus showing the embodiment of the present invention.

FIG. 7 shows a Pt (111) surface showing one embodiment of the present invention.
It is a figure which shows the ratio spectrum of p-polarized light and s-polarized light at the time of introducing 1.3 * 10 < ³ > Pa ethylene at 50K.

FIG. 8 is a graph showing pressure and temperature dependence of an IRAS spectrum when ethylene is introduced into a Pt (111) surface, showing an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultra-high vacuum apparatus 2 IRAS (Infrared reflection absorption spectroscopy) apparatus 3 Stepping motor 4 Rotating polarizer (wire grid polarizer) 4A 1st timing gear 4B Timing belt 4C 2nd timing gear 5 Glover light source 6 Optical filter 7 Interferometer 8 He-Ne laser 11 Ultra-high vacuum vessel 12 Sample (metal single crystal sample) 13 InSb / MCT semiconductor detector 15 Electronic control unit 16 CPU (Central processing unit) 17 Memory 18 Display unit 19 Interface (I / F) ) Circuit 21 Sample pretreatment container (upper container) 31 IRAS measurement container (lower container) 32, 41 Infrared window 33, 42, 45 O-ring 34 Conflat flange 35 Differential exhaust port 36 Turbo molecular pump 37 Manipulator 38 Small cell 39 Straight line introducer 40 Oil rotation Amplifier 43 the gate valve 44 the refrigerant sump 46 oil diffusion pump 47 liquid nitrogen trap 48 sample holder 49 closed circulation reactor

Claims (8)

[Claims] (1) A polarizer is rotated in synchronization with a scan of a Fourier transform infrared spectroscopic interferometer, and (b) a spectrum of p-polarized light and s-polarized light is alternately integrated in synchronization with the rotation. (C) a method of measuring an infrared reflection spectrum, wherein the ratio of the absorption band of gas phase molecules is offset to obtain an infrared reflection absorption spectrum of a surface species adsorbed on a metal surface. 2. The method for measuring an infrared reflection spectrum according to claim 1, wherein an atmosphere temperature and a pressure on the metal surface can be adjusted. 3. The method for measuring an infrared reflection spectrum according to claim 1, wherein said metal surface is a metal single crystal surface. 4. The method for measuring an infrared reflection spectrum according to claim 3, wherein the surface of the metal single crystal is Pt (111).
A method for measuring an infrared reflection spectrum, comprising measuring the spectrum of ethylene adsorbed on the Pt (111) surface in the presence of ethylene at 10 ³ Pa on the surface. 5. The method for measuring an infrared reflection spectrum according to claim 3, wherein the surface of the metal single crystal is Pt (111).
A method for measuring an infrared reflection spectrum, comprising: measuring a spectrum of ethylene adsorbed on the Pt (111) surface in the presence of ethylene in a 150 K temperature atmosphere in a surface atmosphere. 6. A spectroscopic device for rotating a polarizer in synchronization with scanning by a Fourier transform infrared spectroscopic interferometer, and (b) a metal sample set on the spectroscopic device for setting a metal sample and an atmospheric pressure. A vacuum device that can be set up to near pressure, and (c)
An infrared reflection spectrum measuring device, comprising: a detector for detecting an infrared reflection absorption spectrum. 7. An infrared reflection spectrum measuring apparatus according to claim 6, wherein said vacuum apparatus includes a small cell having a short optical path length for reducing absorption of gas phase molecules. A device for measuring reflection spectra. 8. An infrared reflection spectrum measuring apparatus according to claim 6, further comprising means for adjusting an atmospheric temperature and a pressure of the metal sample.