JP4148340B2 - Method and apparatus for producing nano-sized structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for producing a nano-sized structure that captures single ultrafine particles in a solution and fixes them to a substrate.
[0002]
[Prior art]
In the fields of microelectronics, micromachines, microfabrication, microchemistry, etc., research on capturing, controlling, analyzing, and processing minute objects has been active, and the size of these minute objects has progressed from micro to nano size. . Examples of nano-sized micro objects include fine metal particles, polymers, intracellular organelles, and DNA.
[0003]
As a method for capturing a minute object, a method is known in which a minute object is irradiated with a laser beam and fine particles are captured by using the radiation pressure of the generated light. In particular, the inventors of the present application have developed an optical manipulator device that captures and manipulates microparticles [for example, Document 1: Microchemical Intensive Microtransformation Project (1993), Document 2: Production and Technology, Vol. 51, No. 4 pp 59-62 (1999), Reference 3: Toray Research Center THE TRC NEWS No. 62 (1998)].
[0004]
In this method of capturing fine particles by the radiation pressure of light, when the light is extinguished, the particles become the original random motion. Therefore, in order to analyze and process the particles, it is necessary to fix the particles.
[0005]
Further, the inventors of the present application have proposed a method of bonding and fixing a polymer having a size of several microns on a polymer substrate [for example, disclosed in JP-A-11-277269].
[0006]
Furthermore, the inventors of the present application have published a method for arranging and fixing a plurality of nanoparticles [for example, Document 4: The 61st Japan Society of Applied Physics (2000.9.3)].
[0007]
[Problems to be solved by the invention]
However, in the above-described conventional method for capturing and fixing fine particles, the lower limit of the size of fine particles that can be captured is at most several hundred nm, and there is no example in which fine particles having a size smaller than that are captured and fixed alone. This is because the microparticles of this size cannot be observed with a microscope and cannot be seen, so that it cannot be proved that they have been captured and fixed.
[0008]
In view of the above circumstances, an object of the present invention is to provide a method for producing a nano-sized structure and an apparatus for the same that capture and further fix gold fine particles on the order of several nm to several hundred nm.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides
[1] In the method for producing a nano-sized structure, gold fine particles having a size of several nanometers to several hundred nanometers dispersed in a solution with a first laser beam having a wavelength that is not absorbed by the substrate and the gold fine particles The gold fine particles are captured by being focused and irradiated, and the captured gold fine particles are moved to a predetermined position on the surface of the glass substrate by moving a three-dimensional stage of a microscope, and are absorbed by the gold fine particles at a wavelength of 355 nm. a third laser beam having, the captured gold particles to the pulse fluence is condensed and irradiated at about ^{32mJ / cm 2 ~60mJ / cm 2} , the adhesive is fixed to the glass substrate by dissolving the gold fine particles, He-Ne second the gold particles caused by irradiating light scattered laser light comprising laser is captured, it confirmed that it is bonded to the glass substrate child The features.
[0010]
[ 2 ] In the method for producing a nano-sized structure according to [1], gold fine particles of 80 nm are dispersed in water at about 2.2 × 10 ⁹ particles / ml as the gold fine particles, and confirmed with scattered light to obtain 1064 nm. It is characterized by being captured and arranged with a YAG laser.
[0011]
[3] In a nano-sized structure manufacturing apparatus, a first laser composed of a continuous wave-Nd ³⁺ : YAG laser, a second laser composed of a He—Ne laser, and a Q switch—Nd ³⁺ : YAG laser A third laser having a wavelength of 355 nm, an illumination light source including a halogen lamp, a liquid sample in which gold fine particles having a size of several nanometers to several hundred nanometers are dispersed, and the liquid sample are mounted. A glass substrate, a three-dimensional stage of a microscope that moves the glass substrate to a predetermined position, and a CCD camera, and the first laser beam is focused and applied to the gold fine particles dispersed in the solution. means for capturing the gold fine particles, the pulse fluence of the third laser light to the captured gold particles condensing from about 32mJ / cm ² ~60mJ / cm ² And irradiating, and means for fixedly bonded to the glass substrate by dissolving the gold particles, the gold particles cause scattered light irradiating the second laser light is captured, and is bonded to the glass substrate And the CCD camera for confirming this.
[0012]
According to the present invention, the adhesive without using a photopolymerization agent, the metallic fine particles captured, the third laser beam is irradiated to the boundary surface of the fine metal particles and the substrate, by dissolving the gold substrate Fix it. Disperse 80 nm gold particles in water at about 10 ⁹ particles / ml , irradiate a second laser beam to generate scattered light, confirm that the gold fine particles are captured by this scattered light, and use a 1064 nm YAG laser. The laser beam is captured and arranged, and fixed with a third pulse of 355 nm short pulse light that is the third laser light . In addition to the elucidation of substances by analysis with a single ultrafine particle, it is expected to produce a new structure by arranging and assembling ultrafine particles.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0014]
FIG. 1 is a schematic diagram of an optical manipulation and optical immobilization system showing an embodiment of the present invention.
[0015]
In this embodiment, the manipulation and fixation of gold fine particles in a solution by a focused laser beam will be described. That is, a method for fixing gold fine particles on a glass substrate at room temperature and in a solution will be described.
[0016]
In this figure, 1 is a CW (continuous oscillation) -Nd ³⁺ : YAG laser (first laser: wavelength 1064 nm, Spectron Laser Systems, SL-902T), 2, 8 and 18 are mirrors, and 3 is a He-Ne laser. (Second laser), 4, 9 and 11 are dichroic mirrors, 5, 7, 10 and 12 are lenses, 6 is a Q switch-Nd ³⁺ : YAG laser (third laser: wavelength 355 nm, Nd ³⁺ : YAG laser (Spectron Laser Systems, SL-282G, pulse width is about 6 ns, repetition is about 5 Hz), 13 is a liquid sample (sample) in which fine metal particles are dispersed, 14 is a glass substrate, 15 is a three-dimensional stage of a microscope, 16 Is a CCD camera, and 17 is a halogen lamp for illumination.
[0017]
In this embodiment, the sample 13 in which single gold fine particles having a diameter of 80 nm are captured by the laser beam A having a wavelength of 1064 nm from the first laser 1 and moved to the surface of the glass substrate 14. Next, as a result of irradiating the gold fine particles with pulsed light C having a wavelength of 355 nm from the third laser 6, the pulse intensity is about 45 mJ / cm ² and the gold fine particles are fixed on the glass substrate 14 with the same size as before. I was able to. When the pulse energy is about 160 mJ / cm ² , fragmentation occurs, and the gold fine particles are pulverized into several small particles having a size of about 10 to 40 nm. The immobilization mechanism will be explained from the viewpoint of transient temperature rise.
[0018]
Nanoparticles are located between single atoms and bulk and exhibit various interesting features derived from their size. For example, fine gold particles of several tens of nanometers have a remarkable absorption band in the visible region as a result of surface plasmon resonance. In many cases, the object of research is an assembly of a large number of nanoparticles. However, each nanoparticle has a different size, defect, and shape, and only averaged information can be obtained simply by measuring a set of nanoparticles.
[0019]
Therefore, investigating the properties of individual nanometer-sized materials is currently the most important and difficult field in the fields of physics, chemistry and biology. In particular, it is expected that recognizing, manipulating, and immobilizing individual nanoparticles in a solution at room temperature will be very useful for future science and technology.
[0020]
Laser manipulation is a very effective way to handle small objects in a small area. Laser manipulation makes it possible to capture, manipulate, recognize, process and assemble fine particles in solution by using an optical microscope at room temperature.
[0021]
Until now, much research has focused on micrometer-sized objects such as polymer latex, crystals, and living cells, and nanometer-sized objects have rarely been studied. This is because nanometer-sized objects cannot be viewed with an optical microscope in principle and are difficult to confirm. In practice, however, laser manipulation can handle nanometer-sized particles.
[0022]
First, as a first attempt, a method for fixing optically collected and patterned nanoparticles on a glass substrate by photopolymerization has already been proposed.
[0023]
The present invention is a method for fixing single gold fine particles on a glass substrate at room temperature.
[0024]
(1) First, single 80 nm diameter nano gold fine particles are captured and manipulated on the glass substrate 14.
[0025]
(2) Next, the pulsed laser beam is irradiated onto the nano-particles and fixed on the glass substrate 14. The advantage of this method is that the metal fine particles can be fixed without using an adhesive.
[0026]
Hereinafter, it will be described in detail with reference to FIG.
[0027]
As a sample, gold fine particles (British BioCell, EM.GC80, diameter of 80 nm) are dispersed in ethylene glycol. For capturing, a Gaussian beam A having a wavelength of 1064 nm from the first laser 1 is used, and a sample (sample 100) is passed through an objective lens [× 100, numerical aperture (NA) = 1.30] 12 of an optical microscope (Nikon, Optiphoto 2). The solution was condensed in 13).
[0028]
Next, the gold fine particles were fixed using the third harmonic (wavelength: 355 nm) of the third laser 6. P ₁₀₆₄ and P ₃₅₅ , which are the intensity of the capturing laser beam and the intensity of the fixing laser beam, were determined by the methods already announced. The manipulation and immobilization procedures in the liquid sample 13 in which the metal fine particles were dispersed were monitored by a charge coupled device (CCD) camera 16 attached to the microscope.
[0029]
By the above-described method, single 80 nm diameter gold fine particles can be stably captured three-dimensionally with P ₁₀₆₄ of about 36 mW. Since the refractive index is too large, when illuminated with illumination light, the light is scattered by the fine particles, and as shown in FIG. 2, it is observed as a shadow in the optical microscope, and it can be confirmed that the fine particles are captured. .
[0030]
The presence of fine particles can also be confirmed by separately irradiating the fine particles with a second laser beam B to generate scattered light.
[0031]
The captured gold fine particles are moved to a predetermined position on the surface of the glass substrate 14 by moving the three-dimensional stage 15 of the microscope. The three-dimensional stage 15 of this microscope is manually operated, and its minimum step is about 1 μm.
[0032]
Further, the 355 nm pulsed light C from the third laser 6 condensed at the same point as the captured laser beam is irradiated, and the captured nanoparticles are immobilized on the glass substrate 14.
[0033]
Next, the glass substrate 14 was washed with distilled water, and the liquid sample 13 in which the metal fine particles were dispersed was separated and observed with an optical microscope and an atomic force microscope (AFM). The concentration of the gold fine particles was adjusted so that two or more nanoparticles were not captured during the immobilization process. In this experiment, about 2.2 × 10 ⁹ particles / ml was the optimum condition.
[0034]
Next, a series of immobilization experiments were conducted in order to examine the dependency of the immobilization laser intensity. Throughout the experiment, the irradiation time of the immobilized laser pulse was maintained at about 5 s. Since the 355 nm laser pulse is not visible and the substrate position fluctuates in the vertical direction due to the mechanical vibration of the three-dimensional stage 15 of the microscope, the spot size (ie, beam intensity) of the immobilized laser pulse on the glass substrate 14 is determined. Although it is very difficult, the spot size was estimated to be about 2 μm by applying fluorescent ink to a glass substrate and observing light emission from the substrate.
[0035]
FIG. 3 shows that the gold remaining on the glass substrate 14 in distilled water after the sample solution 13 in which the metal fine particles were dispersed was washed out by immobilizing the pulse fluence at about 16 mJ / cm ² , 32 mJ / cm ² , and 60 mJ / cm ^2. Fine particles are shown.
[0036]
Immobilization was repeated 5 times for each pulse output. as a result,
When the fluence was about 16 mJ / cm ² [see FIG. 3A], the gold fine particles could not be fixed on the glass substrate. On the other hand, when the fluence was about 32 mJ / cm ² and 60 mJ / cm ² , 3 and 5 gold particles remained on the substrate (see FIGS. 3B and 3C). The immobilized particles were strongly adhered to the glass substrate to withstand running water.
[0037]
FIG. 3 clearly shows that the threshold for fixing gold particles is about 32 to 60 mJ / cm ² under the experimental conditions. When the fluence was about 16 mJ / cm ² , the gold particles could not be fixed no matter how many times the immobilization procedure was repeated.
[0038]
Further, indicated by different immobilization laser power (fluence of about ^{46mJ / cm 2, 80mJ / cm} 2, 160mJ / cm 2), when immobilized gold particles, atomic force microscope (AFM) image in Figure 4 .
[0039]
As shown in FIG. 4A, when the fluence was about 46 mJ / cm ² , the gold fine particles were not split. FIG. 4 (d) shows that the splitting occurs at a fluence of about 160 mJ / cm ² and the post-split size is about 10 to 40 nm. Fragments were fixed in the 200 × 200 nm region. When the fluence was about 80 mJ / cm ² , the gold fine particles were fixed while maintaining their size as in the case where the fluence was about 46 mJ / cm ² [FIG. 4 (b)]. Splitting occurred due to fluctuations (FIG. 4 (c)).
[0040]
From these results, by controlling the immobilization laser output, not only the single gold fine particles are fixed on the glass substrate but also decomposed into smaller fine particles and fixed on the glass substrate.
[0041]
This result can be explained by the temperature increase of the gold fine particles. The fact that noble metal fine particles are reduced in size by laser pulse irradiation is described in Takami et al. Kamat et al. Have already been reported. In their literature, when gold particles are irradiated with a laser pulse, they dissolve (in the case of low pulse energy) or are pulverized into several small particles of several to 20 nm size (with high pulse energy). If) states that.
[0042]
Under these experimental conditions, the order of fluence is Takami et al. Is equivalent to Laser-induced adhesion is thought to be due to transient dissolution, but the detailed mechanism has not been fully elucidated. However, the laser-induced fixing method is novel and is a very effective method for fixing metal fine particles to a substrate in a solution.
[0043]
In addition, it is also possible to arrange a single nanoparticle on a glass substrate by repeating the same manipulation and immobilization procedure.
[0044]
FIG. 5 is an AFM image in which single gold fine particles of 80 nm are continuously and spatially arranged. Eight gold fine particles were arranged in an “I” shape with a size of about 2.5 μm on a glass substrate with an immobilizing laser fluence of about 45 mJ / cm ² .
[0045]
Thus, single gold particles could be captured on a glass substrate, manipulated, immobilized and spatially arranged. This technique is very important in that minute substances in a solution can be manipulated and immobilized at room temperature.
[0046]
This micromanipulation-immobilization technology of the present invention is expected to be a useful technology for both future nanoscience, research and application in nanotechnology.
[0047]
In addition, this invention is not limited to the said Example, A various deformation | transformation is possible based on the meaning of this invention, and these are not excluded from the scope of the present invention.
[0048]
【The invention's effect】
As described above in detail, according to the present invention, metal fine particles of the order of several nanometers to several hundred nanometers can be captured singly and further fixed.
[Brief description of the drawings]
FIG. 1 is a schematic view of an optical manipulation and optical fixation system showing an embodiment of the present invention.
FIG. 2 is an optical microscopic image of 80 nm diameter single gold fine particles optically captured in ethylene glycol according to an example of the present invention.
FIG. 3 shows an example of gold fine particles fixed on a glass substrate in distilled water after the laser fluence of an embodiment of the present invention was fixed at about 16 mJ / cm ² , 32 mJ / cm ² , and 60 mJ / cm ² . It is an optical microscope image figure.
Example of laser fluence of the present invention; FIG is, after fixed at about ^{45mJ / cm 2, 80mJ / cm} 2, 160mJ / cm 2, was immobilized gold particles on a glass substrate in air It is an AFM image figure.
FIG. 5 is an AFM image view of gold fine particles arranged in an “I” shape after immobilization of an example of the present invention.
[Explanation of symbols]
1 CW (continuous wave) -Nd ³⁺ : YAG laser (first laser: 1064 nm laser beam)
2,8,18 mirror 3 He-Ne laser (second laser)
4,9,11 Dichroic mirror 5,7,10,12 Lens 6 Q switch -Nd ³⁺ : YAG laser (third laser)
13 Liquid sample in which fine metal particles are dispersed (sample)
14 Glass substrate 15 3D stage of microscope 16 CCD camera 17 Halogen lamp for illumination

Claims (3)

(A) a first laser beam, converging and irradiating to the gold fine gold particles of a size of a few hundred nanometers from a few nanometers, which is dispersed in a solution having a substrate and a wavelength that is not absorbed by the gold particles Capture
(B) moving the captured gold fine particles to a predetermined position on the surface of the glass substrate by moving a three-dimensional stage of a microscope;
(C) absorbed to the gold fine particles, a third laser beam having a wavelength of 355 nm, pulse fluence is condensed and irradiated at about 32mJ / cm ² ~60mJ / cm ² to the captured gold particles, the was dissolved gold particles adhered and fixed on the glass substrate,
(D) A nano-size structure characterized by irradiating a second laser beam composed of a He—Ne laser to generate scattered light, and confirming that the gold fine particles are captured and fixed to the glass substrate. Body manufacturing method. The manufacturing method of claim 1 nanosize structure according, the 80nm gold particles as the gold fine particles are dispersed in 2.2 × 10 about ⁹ cells / ml in water, it was confirmed by the scattered light, with YAG laser 1064nm A method for producing a nano-sized structure characterized by capturing and arranging. (A) a continuous wave-Nd ³⁺ : first laser comprising a YAG laser;
(B) a second laser comprising a He-Ne laser;
(C) a third laser having a wavelength of 355 nm comprising a Q-switch-Nd ³⁺ : YAG laser;
(D) an illumination light source comprising a halogen lamp;
(E) a liquid sample in which gold fine particles having a size of several nanometers to several hundred nanometers are dispersed;
(F) a glass substrate on which the liquid sample is mounted;
(G) a three-dimensional stage of a microscope that moves the glass substrate to a predetermined position;
(H) a CCD camera;
(I) said first laser beam, means for the gold fine particles are dispersed in the solution by irradiation condenser captures the gold fine particles,
(J) said third pulse fluence on the captured gold particles laser light is irradiated condensing at about ^{32mJ / cm 2 ~60mJ / cm 2} , is bonded to the glass substrate by dissolving the gold particles Means ,
(K) The nano camera comprising: the CCD camera that irradiates the second laser light to generate scattered light, and the gold fine particles are captured and confirmed to be bonded and fixed to the glass substrate. Size structure manufacturing equipment.

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