JP2003098076A - Infrared absorption spectrum measuring method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the infrared absorption spectrum measuring method and device capable of being applied to the measurement of the infrared absorption spectrum for infrared spectro-rheology of a measured material. SOLUTION: In this infrared absorption spectrum measuring method, an opening part is formed on an approximately central part of a block fixed to a base through a supporting frame, a prism for measuring the attenuated total reflection is fixed to an upper face of the opening part by a fixing means such as a clamp, a tip side of a piezo-actuator (hereinafter referred to as P), is inserted into the opening part to be abutted on a rear face of the measured material, the positioning of the P is performed by a micrometer connected to a rear end of the P, the distortion generated on the P is detected by a distortion gauge mounted on a side face of the P for controlling and correcting the driving of the P, the infrared ray is entered to the measured material through the prism, the pressure is periodically applied from a back side of the measured material by the driving of the P, and a modulation signal by the infrared absorption corresponding to the change of the pressure is taken out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared absorption spectrum measuring method and apparatus, and relates to an infrared spectro-rheology of a manufactured product or its material or a semi-processed product (abbreviated as a material to be measured in this specification) ( Spectro-rhe
for measuring the infrared absorption spectrum by the attenuated total reflection method (ATR method) for the purpose of identifying the components of non-transferable ultratrace substances adhering to the surface of the material to be measured. It is used for measuring the infrared absorption spectrum by the surface-enhanced infrared absorption-attenuated total reflection method (ATR method) using an ultrafine island-shaped metal film.

[0002]

2. Description of the Related Art A generally known transmission method is used as an infrared absorption spectrum measurement method for identifying an ultratrace substance adhering to the surface of a material to be measured in an ultrathin layer on the order of nanometers. In addition, the ATR method (attenuated total reflection method: At
tented TotalReflenction
Method).

From a transparent first medium (ATR prism) having a large refractive index to a transparent second medium (material to be measured) having a small refractive index
When light is incident on the second medium, a phenomenon of total reflection (ATR) occurs when the incident angle exceeds a certain angle, but even if total reflection does not mean that no light is incident on the second medium,
The light that has passed through the medium travels along the interface with the second medium, and there is an evanescent field in which the amplitude exponentially decreases in proportion to the distance from the interface, and this evanescent field exists. If there is a substance, the substance absorbs light peculiarly, and an infrared absorption spectrum is obtained. AT
The R method is an application of this principle.

The above-mentioned infrared spectro-rheology is
Infrared light is projected while cyclically applying mechanical stress such as tension, pressure, and shear stress to the measured material, and the infrared absorption spectrum of the measured material is analyzed to determine the fluidity of the measured material. It is a method to obtain information on the correlation between physical properties such as viscoelasticity and dynamic mechanical properties and molecular structure such as molecular three-dimensional structure, intermolecular interaction, and change in crystallinity inside the material. For measuring the infrared absorption spectrum by using a Fourier transform infrared spectroscopic device (FTIR) (transmission method-FTIR method), for example, R.I. A. Pa
lmer, et al. Appln. ． Spectros
c. 45, 12 (1991), etc., it has already been put to practical use. Since this method is basically a transmission method, it can be applied only when the material to be measured has a single-layer film structure.

Not only the transmission method or the ATR method, but also a measuring method and apparatus improved so as to be used for spectrum measurement of a material to be measured having a multilayer film structure is disclosed in US Pat. No. 6,178,82.
No. 2 specification (Fig. 1 is a transmission method, F is
ig. 2 shows an example of the ATR method).

[0006]

In the general ATR method, since the analysis depth is 0.2 μm to 1.2 μm, it is necessary that the thickness of the material to be measured or the attached substance is 0.1 μm or more. In addition, since the analysis depth changes depending on the wavelength, it is very difficult to independently obtain information only on the uppermost surface portion of the material to be measured or the deposit.

The above-mentioned US Pat. The apparatus shown in FIG. 2A is a system in which a force is applied to a material to be measured in a tensile direction, but FIG. The device shown in 2B is a device for measuring a spectral change due to stress application / relaxation in the thickness direction of a material to be measured by a Fourier transform infrared spectroscopic device (FTIR).
Although it enables spectrum measurement by the IR method,
Basically, the spectrum measurement system by the transmission method is simply applied as it is to the apparatus by the ATR method, so that there are some problems.

For example, FIG. 2B does not show a specific structure for fixing the prism to the tip of the adapter, but if the prism is fixed and the side that receives the pressure is not fixed enough, the stress generated when pressure is applied to the opposite side. There is a high possibility of running away. When the ATR method is applied, a very large force is required to change the pressure of the material to be measured (in the case of a film, the normal thickness is several tens of μm) in the thickness direction. This force is larger than pulling a thin film of several μm in the length direction in the transmission method. Therefore, the side that receives the pressure needs to be fixed more firmly than in the case of the permeation method, but there is no sufficient disclosure regarding these technical requirements.

Further, in the above-mentioned US patent, FIG. As shown in Fig. 1, pressure change is transmitted and / or transmitted from a piezo actuator through a complex transducer that combines many parts such as push rod, lever, hinge and adapter.
Or, since the method of amplifying and applying is adopted, it is indispensable to completely manage and grasp the physical properties such as thermal expansion characteristics and hysteresis characteristics of individual parts and make the characteristics consistent. Further, since the pressure generation / transmission mechanism is a long process, there is a high possibility that various distortions such as vibration noise from the installation environment will be mixed. Furthermore, it is also susceptible to environmental temperature and humidity. Such an effect is relatively unlikely to occur in the transmission method (usually 50 to 70 μm) having a relatively large displacement amount, but in the ATR method, the optimum displacement amount to be generated is very small (the material to be measured is Although it depends on the thickness and the elastic modulus of the material, the optimum amplitude is about 0.05 μm to 5 μm, and this displacement amount is 1/10 of the tension displacement normally performed in the transmission method.
Therefore, it is inconvenient if the length of the step of the transducer to be interposed is long and the error factor generated in the long step is amplified. Therefore, it is desirable to eliminate such a long transducer. However, eliminating the transducer makes it impossible to secure a space for installing a sensor (displacement sensor, etc.) to remove the hysteresis or nonlinear distortion generated in the piezo actuator that is the source of stress. Newly occurs.

As is apparent from the above, the basic problem of the present invention is to measure the infrared absorption spectrum for the infrared spectro-rheology of the material to be measured, which was difficult to measure by the conventional method, or to measure the infrared absorption spectrum. It is to clarify the infrared absorption spectrum measurement method and device applied to the measurement of the infrared absorption spectrum for the identification of the non-adhesive ultra-trace substance adhering to the surface of the measurement material. The challenges are
Fourier transform infrared spectroscopic device to measure the spectrum change accompanying stress application / relaxation to the measured material by applying periodic pressure to the measured material from the back of the ATR prism with which the measured material is in close contact with the piezo actuator. (FTIR) measurement method and device, and more concrete problem is to clarify improved method and device for applying pressure and / or shear stress to the material to be measured. Yes, an improved method for correcting non-linear distortion such as hysteresis that occurs in piezo actuators.
To clarify the device.

[0011]

The above object of the present invention can be achieved by the following constitution. 1. An opening is provided at a substantially central portion of the block fixed to the base via a support frame, and the attenuated total reflection measurement prism is fixed to the upper surface of the opening by a fixing means such as a clamp and the opening is formed. The tip side of the piezo actuator is inserted into the portion, abuts against the back surface of the material to be measured, and further, the piezo actuator is positioned by the micrometer connected to the rear end of the piezo actuator, and the side surface of the piezo actuator The strain gauge generated in the piezoelectric actuator to detect the strain generated in the piezo actuator to control / correct the drive of the piezo actuator, and to make infrared light incident on the material to be measured through the prism to drive the piezo actuator. By applying pressure periodically from the back side of the material to be measured, the infrared absorption in response to pressure changes Infrared absorption spectrum measurement method, characterized by taking out a modulated signal that.

2. The infrared absorption spectrum measurement according to the above 1, wherein a metal block is provided between the tip of the piezo actuator and the material to be measured, and the pressure applied by the piezo actuator is transmitted to the material to be measured. Method.

3. An opening is provided at a substantially central portion of the block fixed to the base via a support frame, and the attenuated total reflection measurement prism is fixed to the upper surface of the opening by a fixing means such as a clamp and the opening is formed. The tip side of the piezo actuator is inserted into the portion and brought into contact with the back surface of the material to be measured, and further, a micrometer is connected to the rear end of the piezo actuator to serve as a positioning means for the piezo actuator and the piezo actuator. A strain gauge is provided on the side of the piezo actuator to detect the strain generated in the piezo actuator and control the drive of the piezo actuator.
When the infrared light is incident on the material to be measured through the prism by arranging a correcting means, pressure is periodically applied from the back side of the material to be measured, and infrared absorption in response to pressure change is performed. An infrared absorption spectrum measuring apparatus having a structure for extracting a modulated signal.

4. 4. The infrared ray as described in 3 above, wherein a metal block is arranged between the tip of the piezo actuator and the material to be measured, and the pressure applied by the piezo actuator is transmitted to the material to be measured. Absorption spectrum measuring device.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A configuration example of an apparatus will be described with reference to FIG. This device performs infrared spectroscopy and rheology of the material to be measured, and the Fourier transform infrared spectroscopic device (FT) is used to measure the spectrum change associated with stress application / relaxation to the material to be measured.
It is measured by IR).

An ATR designated by reference numeral 100 in FIG.
As a device, a commercially available product (for example, Mag by Nicolet Co., Ltd.
A single reflection ATR measuring device such as na860) can be modified and used, but a specific configuration will be described later with reference to FIGS. 2 and 3.

The ATR device 100 described above includes a fixed base 10
1 is installed in a state where it is mounted on the No. 1, but in order to block external vibration, a vibration proof rubber is installed between the installation floor surface and the fixed base 101 or between the fixed base 101 and the ATR device 100.
A floating structure with a sponge interposed is preferable.

Material 1 to be measured whose infrared spectrum is to be measured
02 is disposed on the plane side of the semi-cylindrical ATR prism 103. The infrared light is reflected by the mirror 104, is incident on the ATR prism 103 at a predetermined angle, and the infrared light absorbed by the measured material 102 is reflected by the mirror 105.1.
It is guided to the detector 107 through a path of 06.

As will be described later, the material to be measured 102 contains:
A piezo actuator 110 that urges toward the ATR prism 103 is connected from below.

The operation of the piezo actuator 110 is such that the sine wave oscillator 112 oscillates from 0.1 Hz to 100 Hz.
It is controlled by a piezo controller 111 which operates with a control signal of 0 Hz, preferably 10 Hz to 100 Hz. The information detected by the detector 107 is input to the arithmetic unit 116 as a surface spectrum of the measured material 102 via the lock-in amplifier 113. The information detected by the detector 107 is input to the arithmetic unit 116 as a reference spectrum through the low pass filter 114. The information on the control signal oscillated from the sine wave oscillator 112 is input to the lock-in amplifier 113 as a reference signal.

Next, the ATR according to the present invention will be described with reference to FIG.
A specific example of the device 100 will be described. ATR prism 10
Is fixed by a clamp 23 on a block 22 fixed to a support frame 21 provided upright on the base 20.

The material of the ATR prism 10 is KRS- which is transparent in the infrared light region (wavelength 2 μm to 15 μm) and has a relatively high refractive index (usually refractive index> 2.0).
Although 5 · ZnSe / diamond / Ge / Si can be used, Ge or Si having a high refractive index can be preferably used. The shape may be various shapes such as a trapezoid, a rhombus, a hemisphere, a kamaboko shape, and a short needle shape. Further, the incident angle that can be used varies depending on the refractive index of the ATR prism to be used.
Available in the range of ° -80 °. However, since it is necessary to minimize the influence of the lower layer absorption due to the normal ATR mode, it is preferable to use Ge or Si having a high refractive index,
It is preferable to set the incident angle to 55 ° to 85 °.

In the infrared absorption spectrum measurement for identifying the ultratrace substance having no transferability and adhering to the surface of the material to be measured, a (ultrafine) island-shaped metal film is arranged on the lower surface of the ATR prism 10. (For the super island metal film, Japanese Patent Application No. 2001
What was described in the specification of No. 221303 can be utilized.

The material 30 to be measured is prepared by being placed on the upper surface of the metal block 31 and arranged so as to come into contact with the lower surface of the ATR prism 10. The material 30 to be measured is subjected to pressure fluctuation by the piezo actuator 40 arranged on the back side of the metal block 31, but at the time of initial setting, the material 30 to be measured and the lower surface of the ATR prism 10 are in contact (pressure) with each other. Changes depending on the position where the piezo actuator 40 is arranged, and therefore is finely adjusted by the micrometer 50.

In the adjustment of the contact state (pressure) by the micrometer 50, for example, in the case of a micrometer head having a pitch of 250 μm, a torque driver is used for a hexagonal bolt having a hole diameter of 2 mm, which is directly installed in the head, and 2 × 1.
When a torque of 0 ⁻² N · m is applied, it is calculated that a force of about 10 N is applied. This state is set as the light contact state, and the pressure (10
The state of applying N.about.50 N) is set as the strong adhesion state. In order to correct the hysteresis generated by itself, a strain gauge 41 is provided to detect the displacement of the piezo element,
Correct according to the amount of displacement. As this correction method, a known method can be appropriately used in addition to the method described below.

A sine wave oscillator can be used to apply the modulation signal to the piezo element of the piezo actuator 40.
The modulation frequency used is 0.1 Hz to 1000 Hz, preferably 1 for the purpose of infrared spectrorheological measurement.
0 Hz to 100 Hz, and 1000 Hz to 10 Hz in the measurement by surface-enhanced infrared absorption using an island-shaped ultrafine metal film.
It is 0 kHz, preferably 5000 Hz to 10 kHz.

The frequency of the modulation signal to be applied is not limited to one wavelength, and a method of simultaneously applying two or more frequencies may be used. In this case, the effect of improving the sensitivity according to the number of frequencies can be obtained.

As a method of demodulating a modulated signal,
There is a lock-in amplifier. Digital signal processing (DSP) built into FTIR or the like may be used. Alternatively, a demodulator designed uniquely may be used.

Metal block 31 that can be used in this embodiment
As the material, it is preferable to use a material having a high hardness and not easily deformed by the stress of the piezo actuator 40. Specifically, a metal material having the following material is used.

Carbon steel having a longitudinal elastic modulus of 150 Gpa or more,
Stainless steel (SUS304, 410, 316, 30
1, etc.), chrome stainless steel, nickel steel, etc. From the viewpoint of corrosion resistance, stainless steel (SUS30
4, 316) is preferable. It is desirable that the surface of the metal block on which the sample contacts be mirror-finished so that the pressure is evenly transmitted to the sample.

Another embodiment of the ATR device 100 shown in FIG. 3 differs from the embodiment shown in FIG. 2 in that the metal block 31 is not present. That is, in this embodiment, the tip of the piezo actuator 40 directly contacts the measured material 30.

Differences in operational effects between the embodiments shown in FIGS. 2 and 3,
That is, the reason for interposing the metal block 31 is as follows.

The purpose of utilizing the metal block is that some of the piezo actuator elements have a stress generating surface (a surface that contacts the sample) that is not smooth but is uneven. With such a structure, the pressure may not be uniformly transmitted to the sample, and therefore it is necessary to interpose the metal block 31. If a piezoelectric actuator element having a smooth stress generating surface can be used, the metal block is not necessary.

FIG. 4 shows an example of a load monitor by the strain gauge 41 and a control circuit for correcting the hysteresis generated in the piezo element itself.

As mentioned above, the specific problems of the present invention are as follows.
Fourier transform infrared spectroscopic device to measure the spectrum change accompanying stress application / relaxation to the measured material by applying periodic pressure to the measured material from the back of the ATR prism with which the measured material is in close contact with the piezo actuator. The purpose is to clarify the method and apparatus for measurement by (FTIR).

The present invention has been outlined above, but the specific problem of the present invention is to apply a periodic pressure to the material to be measured from the back surface of the ATR prism to which the material to be measured is adhered by using a piezo actuator. , Stress applied to the material to be measured
To clarify the method and device for measuring the spectrum change accompanying relaxation with a Fourier transform infrared spectroscope (FTIR), and more specifically, to strengthen the fixation of the prism side that receives stress and to use a transducer. It was to reveal a method of applying pressure and / or shear stress with the minimum necessary, directly with a piezo actuator, or only through a small hard metal block. Next, a more specific description will be given of how the above-mentioned problems are solved.

In order to prevent the ATR prism 10 from being displaced when a stress is applied from the piezo actuator 40, the ATR prism 10 has a block 2
It needs to be firmly fixed to 2. 1 and 2
Shows a mode in which the ATR prism 10 is fixed by the clamp 23. The specific configuration is as follows.

The clamp 23 is provided with a guide leg, and the block 22 is provided with a corresponding guide hole so that the prism and the clamp can be accurately fixed without displacement.
Further, the clamp 23 is firmly fixed with two or more fixing screws. The block 22 is provided with a guide groove for accurately mounting the prism in the central portion of the block 22 (or so that pressure is applied to the central portion of the prism). The block 22 is connected to the base 20 via the frame 21, and the block 21 and the frame 21 include a metal block 31, a piezo actuator 40, and a micrometer 5.
A hole for inserting 0 is provided, and the metal block 31, the piezo actuator 40, and the micrometer 50 parts are mounted from the base 20 side. Before fixing the prism 10 to the block 22, the material 30 to be measured is placed on the metal block 31 and supplied. A strain gauge is bonded to the side surface of the piezo actuator 40. When the island-shaped metal film is used, the ATR prism 10 on which the island-shaped metal film is formed in advance is used.

The members used in these fixing devices are preferably high-strength carbon steel having a longitudinal elastic modulus of 150 Gpa or more, stainless steel (SUS304, 410, 316, 301, etc.), chrome stainless steel, nickel steel and the like. From the viewpoint of corrosion resistance, stainless steel (SUS30
4, 316) is preferable.

In place of or in addition to the method of fixing the ATR prism 10 by the clamp 23 described above, a publicly known and publicly known structure can be adopted.

"To stop the use of the transducer to a necessary minimum" has the following meaning. That is, in the device described in the above-mentioned US Pat. No. 6,178,822, the stress generated by the extension deformation of the piezo element is first fixed by the hinge through the extension of the push rod. To one end side of the lever, then transmitted to the push rod connected to the other end side of the lever, and further transmitted to the back side of the material to be measured through a sample holder connected to the tip of the push rod, When the extension deformation of the piezo element stops and returns to the original shape, the lever returns to the original position by the force of the spring attached to the push rod connected to the other end side of the lever, and the pressure on the measured material is The configuration is such that the application is canceled. For this reason, as mentioned above, it is indispensable to completely manage and grasp the physical properties such as thermal expansion characteristics and hysteresis characteristics of the individual parts that make up the transducer, and to match the characteristics. Since the pressure generation / transmission mechanism is a long process, there is a high possibility that various distortions such as vibration noise from the installation environment will be mixed, and it is also susceptible to environmental temperature / humidity, and the ATR method is applied. It is susceptible to unfavorable effects.

In the present invention, a complicated stress transmission mechanism (transducer) as shown in the above-mentioned US patent is not used, but one end side of the piezo actuator 40 directly abuts on the material 30 to be measured. It is adopted. Also,
As described above, in another aspect, the configuration in which the metal block 31 is interposed between the tip end side of the piezo actuator 40 and the measured material 30 is adopted.

Still another object of the present invention is to correct nonlinear distortion such as hysteresis generated in a piezo actuator by attaching a strain gauge to the side surface of the piezo actuator and monitoring / correcting the occurrence of the distortion. It was to clarify the method of applying the stress with high accuracy.
Next, a more specific description will be given of how the problem is solved.

A strain gauge is attached to the side surface of the piezo actuator, and the magnitude of the strain generated here is detected. The strain gauge is an element whose value changes linearly according to the magnitude of the generated strain, and introduces this into a Wheatstone bridge circuit to convert the change in resistance into a voltage change. The obtained voltage is amplified to a predetermined voltage by an amplifier such as a dynamic strain measuring device, and a signal for correction is taken out. Since this voltage changes in proportion to the generated distortion amount, the difference component from the input oscillation signal includes the hysteresis signal and the nonlinear distortion signal generated in the piezo actuator. Therefore, the difference between this voltage change and the original oscillation signal is taken out by the differential amplifier, converted into the original oscillation signal by the addition amplifier, and returned to the piezo controller that drives the piezo actuator. And non-linear distortion can be corrected.

With reference to FIG. 5, an example of an ATR spectrum by infrared spectrorheology according to the method (apparatus) of the present invention will be described. In this example, a polyethylene terephthalate film is used as the material to be measured.

The following is clear from FIG. Thus, it was possible to clearly observe the periodic intensity change of the spectrum due to the pressure change. In the prior art, this periodic intensity change could not be detected stably, and the fluctuation amount was weak and buried in noise, which was unclear, but the method according to the present invention could clearly capture the signal.

[0047]

According to the present invention, even for the material to be measured which could not be measured by the conventional method, the infrared absorption spectrum of the attenuated total reflection method (ATR method) for infrared spectro-rheology can be measured. Measurement can be performed stably and surely. Especially, the prism side that receives stress is firmly fixed, the use of the transducer is minimized, and the piezoelectric actuator is used directly or a small metal block with high hardness. It is possible to apply pressure and / or shear stress only through one, and correction of non-linear strain such as hysteresis generated in the piezo actuator can be performed by a strain gauge on the side surface of the piezo actuator and / or the metal block. Incorporating a method of pasting and monitoring and correcting the occurrence of strain makes it possible to apply stress with high accuracy, solving the problems mentioned above. It is.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an apparatus according to the present invention.

FIG. 2 is a schematic sectional view showing an embodiment of an ATR device according to the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the ATR device according to the present invention.

FIG. 4 is a diagram showing a hysteresis correction mechanism according to the present invention.

FIG. 5 is a graph showing an ATR spectrum by infrared spectroscopy rheology.

[Explanation of symbols]

10-ATR prism 20-base 21-Supporting frame 22-block 23-Clamp 30-Material to be measured 31-Metal block 40-piezo actuator 41-Strain gauge 50-micrometer 100-ATR device 101-fixed stand 102-Material to be measured 103-ATR prism 104-mirror 105-mirror 106-mirror 107-detector 110-piezo actuator 111-piezo controller 112-Sine Wave Generator 113-Lock-in amplifier 114-low pass filter 116-arithmetic unit

Claims (4)

[Claims] 1. An opening is provided at a substantially central portion of a block fixed to a base via a support frame, and an attenuating total reflection measuring prism is fixed to an upper surface of the opening by a fixing means such as a clamp. At the same time, the tip side of the piezo actuator is inserted into the opening, abutting against the back surface of the material to be measured, and further positioning of the piezo actuator by a micrometer connected to the rear end of the piezo actuator, Strain gauges arranged on the side surface of the piezo actuator detect the strain generated in the piezo actuator to control and correct the driving of the piezo actuator, and to make infrared light incident on the measured material through the prism, By driving the piezo actuator, pressure is periodically applied from the back side of the material to be measured, and it responds to the pressure change. Infrared absorption spectrum measurement method, characterized by taking out a modulated signal by infrared absorption. 2. The metal block is arranged between the tip of the piezo actuator and the material to be measured, and the pressure applied by the piezo actuator is transmitted to the material to be measured. Method for measuring infrared absorption spectrum of. 3. An opening is provided at a substantially central portion of a block fixed to a base via a support frame, and an attenuating total reflection measurement prism is fixed to an upper surface of the opening by a fixing means such as a clamp. At the same time, the front end side of the piezo actuator is inserted into the opening and brought into contact with the back surface of the material to be measured, and further, a micrometer is connected to the rear end of the piezo actuator to serve as positioning means for the piezo actuator. At the same time, a strain gauge is provided on the side surface of the piezo actuator to detect a strain generated in the piezo actuator to control and correct the driving of the piezo actuator, and the material to be measured is passed through the prism. On the other hand, when infrared light is made to enter, pressure is periodically applied from the back side of the material to be measured, and the infrared absorption changes in response to the pressure change. Infrared absorption spectrum measuring apparatus which is a configuration for taking out the signal. 4. A structure in which a metal block is arranged between the tip of the piezo actuator and the material to be measured, and the pressure applied by the piezo actuator is transmitted to the material to be measured. 3. The infrared absorption spectrum measuring device described in 3.