JP6432817B2 - Sample optical measurement method - Google Patents

Description

  The present invention relates to an optical measurement method useful for measuring a sample with a Fourier transform infrared spectrometer or an infrared spectrometer. Specifically, a polymer thin film is formed on the surface of the optical member that comes into contact with the sample to prevent the sample from coming into direct contact with the surface of the optical member, and the polymer contaminated by the sample coming into contact with it. The present invention relates to an optical measurement method capable of keeping the surface of an optical member clean by removing a thin film.

  Optical members such as lenses and mirrors that are provided in optical equipment such as cameras, telescopes, microscopes, and projection devices used in the manufacture of electronic devices are exposed to the external environment, and foreign objects are exposed to the surface. Adhering causes a decrease in light transmittance and illuminance unevenness, and the original optical performance cannot be obtained. For this reason, it is common practice to remove foreign substances adhering to the surface of these optical members by wiping them with a dry cloth or nonwoven fabric or a cloth or nonwoven fabric impregnated with water or alcohol.

  For example, in Patent Document 1, as a method of removing deposits on the surface of an optical member of a projection exposure apparatus used for manufacturing an electronic device such as a semiconductor element, first, wipe with pure water, then methanol, etc. using a nonwoven fabric A method of wiping with alcohol is disclosed. Further, in Patent Document 2, as a method for removing deposits on the surface of an optical member of a projection exposure apparatus used for manufacturing an electronic device such as a semiconductor element, it is wiped with an etching solution containing hydrofluoric acid and then remains. A method of wiping off the etching solution with water or an organic solvent is disclosed.

  On the other hand, in an optical device such as a spectrophotometer used for analyzing and identifying a substance, a target sample is placed on an ATR crystal (prism) as an optical member, like a Fourier transform infrared spectrometer using the ATR method. In the spectrometer of the type that is brought into contact with the sample, the sample often adheres and remains on the optical member. Therefore, after the measurement is completed, it is necessary to remove the sample remaining on the surface of the optical member. The removal operation must be simple, quick and effective.

  However, if the sample is sticky, a large amount of sample remains on the surface of the optical member, or it adheres firmly, so just wipe it with a nonwoven fabric impregnated with a solvent. It may not be completely removed and the wiping operation may have to be repeated, which makes the operation cumbersome and cumbersome. When the deposit is a granular substance, the surface of the optical member may be damaged by repeating the wiping operation.

  In the case of an analyzer such as the above-described Fourier transform infrared spectrometer, due to its characteristics, the target sample is often an unknown substance, and removal of the sample to which a solvent prepared in advance for wiping work is attached In some cases, the wiping operation must be repeated while changing the type of the solvent by trial and error, and the wiping operation may be an extremely complicated operation. In order to avoid such a wiping operation by trial and error, it is necessary to separately search for a solvent having an affinity for the sample in advance, which also requires complicated work.

  In addition, there may be cases where radioactive or harmful substances that are permitted to be handled only within the controlled area are attached to the sample. In this case, since it is dangerous to touch the deposits on the surface of the optical member, avoid contact with the deposits by wiping work as much as possible, and waste such as non-woven fabric containing radioactive substances and harmful substances It is necessary to reduce the occurrence of Furthermore, when a residual deposit is generated on the optical member, an expensive measuring device cannot be used outside the management area. Therefore, there is a demand for a method that can be measured safely with the simplest possible operation.

JP 2002-336804 A Republished WO 2004/050266

  The present invention prevents contamination of the optical member caused by adhesion of the sample remaining on the surface of the optical member (in the present invention, this is referred to as “residual sample”) to remain on the surface of the optical member. It is an object of the present invention to provide an optical measurement method that can ensure work speed and safety without adversely affecting the operation.

In order to solve the above-mentioned problems, the present inventor has intensively studied, and as a result, applied to the surface of the optical member is a polymer thin film by applying a dilute solution in which a polymer compound that forms a transparent and flexible film is dissolved in a volatile solvent. It is found that by removing the polymer thin film after measurement, contamination of the optical member can be prevented without adversely affecting the optical measurement, and the speed and safety of the operation can be secured. Reached.
That is, the present invention is as follows.

(1) an optical measurement of the sample, the surface of the optical member sample is in direct contact, the thickness of the dilute solution of the polymer compound of rubber dissolved in a volatile solvent of hydrocarbon by coating of Forming a polymer thin film having a thickness of 0.5 μm or less, performing optical measurement in a state where the sample and the surface of the optical member are not in direct contact, and then removing the polymer thin film.
(2) The optical measurement method according to (1), wherein the rubber-based polymer compound is chloroprene rubber.
(3) The optical measurement method according to (1) or (2), wherein the optical member is a lens, a prism, a mirror, or a cell.
(4) The optical measurement method according to (1) or (2), wherein the optical member is a prism of a Fourier transform infrared spectrometer.

According to the optical measurement method of the present invention, a dilute solution of a rubber-based polymer compound dissolved in a volatile solvent is applied to the surface of the optical member to form a polymer thin film. The sample can be prevented from adhering and remaining, and the surface of the optical member can always be kept clean by removing the polymer thin film to which the sample has adhered and remained. Moreover, if the polymer thin film formed on the surface of the optical member is removed, the residual sample can be easily removed, so that the safety of the operator and the measuring device can be ensured, and the management within the management area is possible. Even if necessary samples remain attached, they can be disposed of in the controlled area.

It is the figure which contrasted and showed the infrared spectrum about the sample (polypropylene) measured before and after forming the thin film of the chloroprene rubber of this invention in the surface of the ATR crystal (prism) of a Fourier-transform infrared spectrometer.

  The present invention is a method for optical measurement of a sample, wherein a thin film of a polymer compound dissolved in a volatile solvent is applied to the surface of an optical member in contact with the sample to form a polymer thin film. And the surface of the optical member are not in direct contact with each other, and then the polymer thin film to which the sample is adhered and removed is removed by contact with the sample.

  The optical member is not particularly limited as long as it is a member that directly contacts an optical measurement sample. Examples thereof include optical members such as lenses, prisms, and mirrors used for transmission, refraction, and reflection of electromagnetic waves such as visible light, infrared light, ultraviolet light, and laser light, and measurement cells that sandwich the sample.

  In the optical measurement method of the present invention, the polymer compound used to form the polymer thin film on the surface of the optical member is not susceptible to tearing when the polymer thin film is removed, and has a high light transmittance and optical properties. A compound that forms a transparent and flexible film is preferred in that it has a low possibility of adversely affecting the measurement. In particular, in a Fourier transform infrared spectrometer, the sample to be measured is pressed against the surface of the ATR crystal (prism) by a pressurizing jig, so that if the polymer thin film is hard, the polymer thin film may be torn or cracked. There is a fear.

As such a polymer compound, a rubber-based polymer compound is used , and examples thereof include chloroprene rubber, nitrile rubber, styrene-butadiene rubber, butyl rubber, and natural rubber. Particularly preferred is chloroprene rubber.

The thickness of the polymer thin film is required not to adversely affect the optical measurement, and can be arbitrarily determined according to the type of the optical member, but is 0.5 μm or less in consideration of measurement accuracy. For example, in the Fourier transform infrared spectroscopy by ATR method infrared light exuding to the sample side, ATR crystal kind used (diamond, Z n Se, germanium, silicon, etc.) is controlled by and angle of incidence, Usually, it is about 0.5 to 2.0 μm in the depth direction, and an infrared absorption spectrum of a sample existing in this region is measured. Therefore, when the thickness of the polymer thin film formed on the surface of the ATR crystal (prism) is 0.5 μm or less, the measurement of the infrared absorption spectrum of the sample is not affected.

In forming the polymer thin film is Ru with a dilute solution of the polymer compound of rubber. The concentration of the rubber-based polymer compound is preferably 0.1 to 1.0% by mass, more preferably 0.3 to 0.7% by mass, and particularly preferably 0.4 to 0.6% by mass. Is good. When the concentration is 0.1% by mass or more, it is possible to prevent the occurrence of a portion where the polymer thin film does not exist due to the properties of the surface of the optical member, fine irregularities, etc. A thin film can be formed. If the concentration is 1.0% by mass or less, an increase in the viscosity of the solution can be avoided, so that a dilute solution of a rubber-based polymer compound can be uniformly spread on the surface of the optical member, and the polymer Since the film does not become too thick, the original function of the optical member is not hindered. For example, in the case of an ATR crystal (prism), a dilute solution of a rubber-based polymer compound having a concentration of 0.5% by mass may be applied so as to be 0.1 mg or less per square centimeter.

When preparing a dilute solution of a rubber-based polymer compound, a volatile solvent is used. The volatile solvent can be appropriately selected depending on the optical element material, for example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, Ru a hydrocarbon solvent such as a halogenated hydrocarbon. Among these solvents, aromatic hydrocarbons are preferable and toluene is particularly preferable from the viewpoint of solubility of rubber-based polymer compounds and appropriate volatility.

The method of applying the dilute solution of the rubber-based polymer compound is not particularly limited, and a method of spreading the dilute solution of the rubber-based polymer compound on the surface of the optical member and spreading it naturally, or using a brush or a spatula, etc. A method of spreading by using, a method of spraying, etc. may be used. When the film thickness is increased, a dilute solution of a rubber-based polymer compound is preferably applied a plurality of times. After applying a dilute solution of a rubber-based polymer compound, the thin film is formed by natural drying. In addition, when applying several times, or when a certain unevenness | corrugation may arise in the surface of the thin film formed, in order to increase the formation speed of a thin film, you may blow and dry with warm air .

The optical measurement method according to the present invention can be widely applied to known optical measurement methods. For example, sample analysis using a stationary or portable Fourier transform infrared spectrometer or infrared spectrometer, observation of underground objects with a fiberscope, observation with various microscopes that are difficult to remove if the measurement substance adheres accidentally Can be mentioned. In particular, it is suitable for analysis of samples to which radioactive substances or harmful substances are attached.
Among the above, in the Fourier transform infrared spectroscopic analysis by the ATR method (hereinafter referred to as “ATR method FT-IR”), an extremely excellent effect is exhibited. In other words, in the ATR method FT-IR, when an electromagnetic wave is incident on a medium having a low refractive index from a medium having a high refractive index, if the incident angle is set to a certain critical angle or more, the electromagnetic wave is not slightly on the medium side having a low refractive index but on the interface. This is a measurement method that applies the phenomenon of oozing and reflecting (this reflected electromagnetic wave is called an evanescent wave). When a sample to be measured is brought into contact with a prism called an ATR crystal and infrared light is incident on the ATR crystal, the infrared light oozes out to the sample side and then reflects. Because it absorbs infrared light with a wavelength specific to the compound, the reflected infrared light shows a sample-specific infrared absorption spectrum, and the molecular structure of the sample compound can be analyzed from the spectrum. .

  Residual sample adheres to the polymer thin film formed on the surface of the optical member. By removing the polymer thin film from the surface of the optical member using a cotton swab or tweezers, the residual sample is also removed simultaneously. Therefore, the operation itself is very simple. In addition, in the normal case, it is necessary to attach a residual sample to a non-woven fabric and wipe it off, and there may be multiple times, so a large amount of waste is generated. Only the thin film is discarded, and the amount of waste generated can be reduced. Thus, the surface of the optical member can always be kept clean. If it is difficult to remove the polymer thin film from the surface of the optical member, wipe it off using a cloth, nonwoven fabric or cotton swab impregnated with a solvent that dissolves the polymer compound. The polymer thin film can be removed simultaneously.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited only to a following example.

Example 1
The test was conducted using a portable FT-IR (4100 Exoscan handheld FT-IR, manufactured by Agilent Technologies). A diamond crystal was used as an ATR crystal for measuring an infrared absorption spectrum by the ATR method, and a polypropylene film was used as a measurement sample. As a dilute solution of the polymer compound, a 0.5% toluene solution of chloroprene rubber was used. Chloroprene was neoprene (registered trademark).

  A drop of chloroprene rubber solution (about 0.1 mg) was placed on the surface on which the diamond crystal sample was placed, spread on the surface and air-dried to form a chloroprene rubber thin film having a thickness of about 0.5 μm. . A polypropylene film as a sample was placed thereon, the polypropylene film was pressed against the ATR crystal with a pressure jig, and an infrared absorption spectrum (“sample + chloroprene rubber thin film spectrum” in FIG. 1) was measured. After the measurement, the chloroprene rubber thin film remaining on the surface of the ATR crystal was removed by scraping with a cotton swab impregnated with ethanol.

  On the other hand, after placing a polypropylene film directly on the ATR crystal and pressing it with a pressure jig, an infrared absorption spectrum (“sample only” spectrum in FIG. 1) under the same measurement conditions as the above “sample + chloroprene rubber thin film”. ) Was measured.

FIG. 1 shows the two infrared absorption spectra in comparison. FIG. 1 shows that both spectra are the same, and an infrared absorption spectrum derived from chloroprene rubber is not observed.
In addition, from Example 1 above, the film thickness of the chloroprene rubber thin film formed on the surface of the ATR crystal is made smaller than the measurement depth of the ATR method FT-IR, so that the sample infrared rays are not affected by the chloroprene rubber thin film. It was found that the absorption spectrum can be measured, and the chloroprene rubber thin film after the infrared absorption spectrum measurement can be easily removed by wiping with a solvent.

  The optical measurement method of the present invention is useful as a sample optical measurement method in disaster sites and construction sites.

Claims (4)

An optical measurement method for a sample, in which a dilute solution of a rubber-based polymer compound dissolved in a hydrocarbon-based volatile solvent is applied to the surface of an optical member in direct contact with the sample to obtain a thickness of 0. An optical measurement method comprising: forming a polymer thin film of 5 μm or less, performing optical measurement in a state where the sample and the surface of the optical member are not in direct contact, and then removing the polymer thin film.   The optical measurement method according to claim 1, wherein the rubber-based polymer compound is chloroprene rubber. The optical measurement method according to claim 1, wherein the optical member is a lens, a prism, a mirror, or a cell. The optical measurement method according to claim 1, wherein the optical member is a prism of a Fourier transform infrared spectrometer.