JP2008188523A - Laser light irradiating device, liquid-phase laser ablation apparatus and method of controlling reaction site - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control reaction conditions for reaction sites produced by converging laser light in a liquid. <P>SOLUTION: When laser light is converged in a liquid in a pressurized state, an unexpected high energy is generated at the reaction site produced by the convergence of laser light in the liquid, leading to changes of the reaction conditions for the reaction site. The reaction conditions for reaction sites can thus be controlled by controlling the pressurized state of the liquid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to, for example, a laser beam irradiation apparatus, a liquid phase laser ablation apparatus, and a reaction field control method.

In the liquid phase laser ablation apparatus, a target is irradiated with pulsed laser light in the liquid phase to cause ablation, thereby generating and collecting fine particles of nanometer order.
For example, in the liquid phase laser ablation apparatus described in Patent Document 1, pure water is filled in a reaction vessel, and laser ablation is performed by immersing a metal target in the pure water. Here, a pressure relief is attached to the reaction vessel to keep the pressure constant. The reaction vessel is not provided with any pressurizing device such as a compressor.
Patent Document 2 discloses a technique in which zeolite particles are dispersed in water, and then the zeolite particles are irradiated with a laser beam to pulverize the zeolite particles.

In liquid phase laser ablation, laser light is converged in a liquid, and the converged region of the laser light is defined as a high-temperature and high-pressure region. In this high temperature and high pressure region, the target is finely pulverized to nano-order. Patent Documents 3 and 4 disclose synthesizing a new substance by converging laser light.
That is, the high-temperature and high-pressure region obtained by converging the laser beam has a significantly different environment from the surrounding liquid region, and becomes a reaction field that causes a change in the substance.
For documents relating to the present invention, further refer to Patent Documents 3 to 5 and Non-Patent Documents 1 and 2.

JP 2006-122845 A JP 2006-273623 A JP 2004-283924 A JP 2005-264089 A JP 2003-35671 A Sasaki et al. Journal of Photochemistry and Photobioogy A: Chemistry 182 (2006) 335-341. Changhao et al. Chem. Mater. 2004, 16, 963-965

When a reaction field is formed by converging a laser beam in a liquid and a substance is changed in the reaction field, the substance in the reaction field can be changed by changing the internal environment of the reaction field, in other words, the reaction conditions of the reaction field. It is considered that the mode of change in the above also changes.
It is considered that a high temperature and high pressure state of 5000 K and 7000 atm is generated in the reaction field obtained by converging the laser light in the liquid (Sakka et al. Appl. Surf. Sci. 2002, 197-198, 246-250 And Sakka et al. Appl. Surf. Sci. 2002, 197-198, 56-60.).
No attempt has been made to control the reaction conditions of the reaction field by changing such extreme high temperature and high pressure conditions.
Therefore, an object of the present invention is to control the reaction conditions of the reaction field obtained by converging the laser beam in the liquid.

As a result of intensive studies to achieve the above object, the present inventors have made an unexpectedly large reaction field obtained by converging the laser beam when the liquid is pressurized and the laser beam is focused on the liquid. It was found that energy was generated and the reaction conditions of the reaction field changed greatly. That is, the reaction conditions in the reaction field can be controlled by controlling the pressurized state of the liquid.
The present invention has been made based on the above findings, and the first aspect thereof is defined as follows. That is,
A laser light irradiation unit for converging laser light in a liquid, the laser light irradiation for irradiating the laser light so as to cause a change in a substance existing in the reaction field using a region where the laser light is converged as a reaction field And
A liquid pressurizing unit for pressurizing the liquid;
A laser beam irradiation apparatus comprising:

According to the laser beam irradiation apparatus of the first aspect defined as described above, the reaction conditions can be largely changed in the reaction field that is the convergence region of the laser beam by changing the pressure of the liquid.
The reaction field obtained by converging the laser beam in the liquid is in an extremely high temperature and high pressure state, so even if the liquid temperature or the laser beam power is changed, the internal environment of the reaction field, that is, the reaction conditions hardly change. . On the other hand, changing the pressure of the liquid greatly changes the internal environment of the reaction field. Thereby, the reaction conditions of the reaction field can be controlled.

In the above, any liquid can be adopted as the liquid. For example, water, an organic solvent, an aqueous solution, a colloidal solution, an emulsion or the like can be employed. By adopting water as the liquid, the entire apparatus becomes inexpensive and easy to handle.
A bulk target may be present in the liquid. Liquid phase laser ablation is performed by focusing the laser beam on the surface of the target. The type of target can also be arbitrarily selected.

  The laser beam can be arbitrarily selected as long as it can change the substance by converging it. As a light source of high-power laser light that can change a substance, a general-purpose YAG laser, excimer laser, or the like can be given. The wavelength and irradiation time of such laser light can also be set arbitrarily.

When the laser beam is converged in the liquid, the temperature of the liquid is rapidly raised in the convergence region, and the liquid is evaporated as the temperature rises, so that a high temperature and high pressure state is locally generated. As a result, it is considered that the material breaks down and becomes plasma.
The liquid is filled in the reaction vessel, and a pressurizing device is connected to the reaction vessel. As the liquid pressurizing apparatus, a general-purpose apparatus such as a pump type or a cylinder type can be arbitrarily used. By this pressurizing device, the pressure of the liquid in the reaction vessel is arbitrarily adjusted.

Another aspect of the present invention is defined as follows. That is,
A liquid phase laser ablation apparatus, which pressurizes a liquid into which a target is immersed.
According to such a liquid layer ablation apparatus, the energy of the region where ablation occurs can be increased by pressurizing the liquid.

Still another aspect of the present invention is defined as follows. That is,
A reaction field obtained by converging a laser beam in a liquid, and a method for controlling reaction conditions of a reaction field that causes a change in a substance existing therein,
A reaction condition control method, wherein the reaction condition of the reaction field is controlled by changing the pressure of the liquid.
According to the reaction condition control method defined in this way, it is possible to control a reaction field in an extremely high temperature and high pressure state by a simple method.

FIG. 1 shows a schematic configuration of a laser beam irradiation apparatus 1 according to an embodiment of the present invention.
The laser beam irradiation apparatus 1 includes a laser beam irradiation unit 10, a reaction unit 20, and a pressurization unit 30.
The laser beam irradiation unit 10 includes a laser transmitter 11 and a lens 12, and the pulsed YAG laser beam irradiated from the laser transmitter 11 is converged by the lens 12.
The reaction unit 20 includes a cylindrical reaction vessel 21. A window portion 22 is formed on the laser transmitter 11 side of the reaction vessel 21, and the laser beam 13 converged by the lens 12 passes through the window portion 22 and is focused at the approximate center of the reaction vessel 21. Reference numeral 24 denotes a retainer that can be attached to and detached from the reaction vessel 21 while maintaining airtightness. A target is fixed to the tip of the bulging portion 25 of the retainer 24.

An observation window 26 is formed on the substantially central side wall of the reaction vessel 21 so that an area where the laser beam 13 is converged can be observed. An ICCD camera 27 is attached to the observation window 26. A connecting portion 28 to the pressurizing portion 30 is formed on the facing surface of the observation window 26.
The pressurizing unit 30 includes a rotary pump type pressurizer 31, and an arbitrary pressure is applied to the liquid filled in the reaction vessel 21 by the pressurizer 31. Reference numeral 33 denotes a pressure gauge.

In the laser light irradiation apparatus 1 having the configuration shown in FIG. 1, when the reaction vessel 21 is filled with pure water and irradiated with pulsed YAG laser light, an image of the convergence region of the laser light observed by the ICCD camera 27 is shown in FIG. Shown in The irradiation conditions of the YAG laser are a wavelength: 1.06 μm, laser energy (instantaneous power) 280 mJ / pulse at the time of irradiation, and a single pulse is irradiated. FIG. 2 (A) is an image observed when the pressure in the reaction vessel 21 is 1 atm, and FIG. 2 (B) is observed when the pressure in the reaction vessel 21 is set to 9 atm by operating the pressurizer 31. It is an image.
FIG. 3 shows the change in pressure in the reaction vessel 21 and the integrated luminance of the image observed by the ICCD camera 27 (the average value (black circle) and standard deviation of the integrated luminance of the image obtained each time the laser beam was irradiated 20 times). (Vertical bar)).

2 and 3, it can be seen that as the pressure applied to pure water is increased, the luminance in the laser beam convergence region increases.
This is considered to be due to a change in the number of local electrons or the electron energy state generated at the initial stage of laser irradiation when pressure is applied.
From the results of FIGS. 2 and 3, the pressure applied to the liquid phase is preferably 2 atm or more. More preferably, it is 2-9 atm. According to the study by the present inventors, the pressure applied to the liquid layer can be 2 to 300 atm.
When the laser beam is focused in the liquid, the light emission mode changes depending on the element contained in the liquid. When the liquid is pressurized as in this embodiment, the brightness of the laser light convergence region is increased, so that it is possible to observe light emission based on a trace amount of element that cannot be observed when no pressure is applied. In other words, the element identification sensitivity can be increased without increasing the output of the laser beam.

  Next, a titanium target was fixed to the tip of the bulging portion 25 of the retainer 24, and YAG laser light was focused on the surface of the target. YAG laser is irradiated with a single pulse at a wavelength of 1.06 μm and a laser energy (instantaneous power) of 56 mJ / pulse at the time of irradiation. An image taken by the ICCD camera 27 at that time is shown in FIG. FIG. 4A is an image observed when the pressure in the reaction vessel 21 is 1 atm, and FIG. 4B is observed when the pressure in the reaction vessel 21 is set to 9 atm by operating the pressurizer 31. It is an image. A symbol T in the figure indicates a target.

FIG. 5 shows the change in pressure in the reaction vessel 21 and the integrated luminance of the image observed by the ICCD camera 27 (the average value (black circle) and standard deviation of the integrated luminance of the image obtained each time the laser beam was irradiated 20 times). It shows the relationship with the vertical bar)).
FIG. 6 shows the surface profile of the target after the observation of 1 atm and 6 atm in the above observation results. The result of FIG. 6 was obtained with a stylus type step gauge (manufactured by KLA-Tencor, model number: Alpha-Step 500).
From the result of FIG. 6, it can be seen that even if the pressure applied to the liquid is increased, the influence (ablation amount) on the target hardly changes. In other words, there is no change in the amount of target particles present in the reaction field.
On the other hand, when the pressure applied to the liquid is increased as shown in FIGS. 4 and 5, high brightness is obtained in the reaction field.
From the above, it can be seen that increasing the pressure applied to the liquid increases the internal energy of the substance present in the reaction field. That is, the internal energy of the substance existing in the reaction field can be remarkably increased by slightly changing the pressure applied to the liquid. In other words, the reaction conditions in the reaction field can be greatly changed by slightly changing the pressure applied to the liquid.

  By increasing the pressure of the liquid phase, the energy in the region where the laser beam converges becomes extremely large. Thereby, the laser ablation of a novel aspect can be performed. Furthermore, when a substance is synthesized in a reaction field, there is a possibility that a new substance that has not been obtained can be synthesized.

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

FIG. 1 is a schematic diagram showing a configuration of a laser beam irradiation apparatus according to an embodiment of the present invention. FIG. 2 shows an image observed when the laser light in pure water is converged in the laser light irradiation apparatus of the embodiment. FIG. 2A is an image when pure water is at atmospheric pressure. 2 (B) is an image when pure water is pressurized to 9 atm. FIG. 3 is a graph showing the relationship between the pressure of pure water and the brightness of the observation image. Fig. 4 shows an image observed when liquid phase laser ablation is performed. Fig. 4 (A) shows an image when the liquid phase is set to atmospheric pressure, and Fig. 4 (B) shows that the liquid phase is added up to 9 atm. It is an image when pressed. FIG. 5 is a graph showing the relationship between the liquid phase pressure and the brightness of the observed image. FIG. 6 shows the profile of the target surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam irradiation apparatus 10 Laser beam irradiation part 20 Reaction part 25 Swelling part 30 Pressure part

Claims (9)

A laser light irradiation unit for converging laser light in a liquid, the laser light irradiation for irradiating the laser light so as to cause a change in a substance existing in the reaction field using a region where the laser light is converged as a reaction field And
A liquid pressurizing unit for pressurizing the liquid;
A laser beam irradiation apparatus comprising: The laser light irradiation apparatus according to claim 1, wherein the liquid is water. The laser beam irradiation apparatus according to claim 1, wherein a target is disposed in the reaction field, and laser ablation is generated in the target. The laser beam irradiation apparatus according to claim 1, wherein the liquid is pressurized to 2 to 9 atm. A liquid phase laser ablation apparatus, which pressurizes a liquid into which a target is immersed. A reaction field obtained by converging a laser beam in a liquid, and a method for controlling reaction conditions of a reaction field that causes a change in a substance existing therein,
A reaction condition control method, wherein the reaction condition of the reaction field is controlled by changing the pressure of the liquid. The reaction liquid control method according to claim 6, wherein the liquid is water. The reaction field control method according to claim 6, wherein a target is disposed in the reaction field. The reaction field control method according to any one of claims 6 to 8, wherein the liquid is pressurized to 2 to 9 atm.