JP3097141B2 - Drawing method of organic material using scanning tunneling microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning tunneling microscope.
The present invention relates to a drawing processing method for identifying each element constituting an organic material using (STM) and performing color-coded display corresponding to each element.

[0002]

2. Description of the Related Art In general, a scanning tunneling microscope applies a predetermined voltage between a sample and a probe arranged opposite to the sample, and scans the probe so that a tunnel current flowing between the two becomes constant. By doing so, the shape of the sample surface can be observed at the atomic level resolution.

By the way, although an organic material is generally an insulator, a tunnel current flows. Therefore, there is a demand to observe an STM image of such an organic material.

On the other hand, while the relative position between the sample and the probe is fixed, the voltage applied to the probe is changed, and the so-called I / V obtained by measuring the change in the tunnel current accompanying the change is applied.
It is known that the curve is related to the electron cloud distribution of each atom.

[0005]

Conventionally, STM images obtained by such a scanning tunneling microscope have been color-coded and displayed by image processing.
Each color of the image has no academic meaning at all, and merely serves to improve the appearance. No processing such as distributing colors in accordance with the type of each element is performed.

Further, based on the above I / V curve, ST
Although it is possible to identify the element names contained in the M image,
Determining which element each I / V curve specifically corresponds to requires a lot of experience and effort and is not practical.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to solve the above-mentioned problems.
The structure and structure of the compound can be easily grasped by identifying the element name in the TM image and displaying the color of each element by color.

In organic materials, most of them are carbon
(C), hydrogen (H), oxygen (O), and nitrogen (N), and rarely contains other elements. Therefore, each element forming the STM image is composed of these four elements.
It can be assumed to be any of the elements.

The present invention has been made by paying attention to the above fact, and in the drawing process of an organic material using a scanning tunneling microscope, it is determined by a combination state of atoms contained in a unit block of a certain region. After registering the I / V curve of the central atom in advance, the STM
After taking an image and setting one unit block for this STM image, a first step of measuring the I / V curve of the central atom of this unit block, the actually measured I / V curve and the previously registered I / V curve A second step of checking the degree of coincidence between the two curves by comparing the two curves with the V-curve, and weighting the combination pattern of each atom included in the unit block according to the degree of coincidence. For all other atoms included in the block, a new unit block centering on those atoms is newly set, and the first,
The second step is repeated, and for each combination pattern having a large weighted value, matching is performed based on the unit block set first, and the central atom is selected from the combination pattern of each atom of the unit block set first. One combination pattern that satisfies all the relationships between the element and its surrounding atoms is selected, and a corresponding color is assigned to each of the atoms constituting the selected one combination pattern.

[0010]

According to the above method, element names are identified in an STM image of an organic material, and color-coded display is performed according to each identified element. The configuration and structure can be easily grasped.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flow chart for explaining a method of drawing an organic material using a scanning tunneling microscope according to the present invention.

In this example, as shown in FIG.
It is assumed that one unit block B is composed of = 9 atoms I _{1 to} I ₉ . The central atom I ₁ determined by the combination of the atoms I _{1 to} I ₉ included in the unit block B
Is obtained by simulation, and the simulation result is registered in advance (step 1).

That is, the central atom I ₁ is affected by the electron cloud of the other atoms I _{2 to} I ₉ present around it.
It does not make much sense to simulate the I / V curve of the central atom I ₁ alone, and it is necessary to determine the I / V curve in relation to the atoms I _{2 to} I ₉ present around it.
Therefore, in advance assuming a combination pattern of the central atom I ₁ and its peripheral atoms I ₂ ~I _9, obtained by simulating the I / V curve for each combination pattern. Specifically, in this example, it is assumed that the organic material is basically composed of four elements of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). This unit block B
For, although the combination pattern of the elements 4 ^nine present, in this, because there is also a combination pattern which does not conform to the law of covalent bonds, such unreasonable combination pattern eliminates the remaining combinations for pattern, determined respectively simulating the I / V curve of the central atom I _1, registering these I / V curve data such as the external memory.

Next, an STM image of the organic material sample
Take an (atomic image) (step 2).

Then, as shown in FIG. 2B, a unit block B ₁ having an area of the same size as described above (in this example, an area of 9 atoms) is added to a required portion of the STM image. set, for the unit blocks B _1, actually measure the I / V curve of the central atom I ₁ (step 3).

Subsequently, assuming that the central atom I ₁ of the unit block B _{1 is} , for example, carbon (C), all the registered I / V curves in this assumption are read out from an external memory or the like.
(Step 4).

Then, the read I / V curve is compared with the actually measured I / V curve to determine the degree of coincidence between the two curves, and the I / V curves individually correspond to the respective I / V curves according to the degree of coincidence. The combination pattern of each atom is weighted (step 5).

For example, assuming that the central atom I ₁ of the unit block B ₁ is carbon (C), if there are 500 patterns as a combination of elements of the unit block B ₁ , this corresponds to this. Since there are also 500 I / V curves to be read and read, a deviation of each of these I / V curves based on the actually measured I / V curve is checked, and each of the registered I / V curves is registered according to the magnitude of the deviation. A weight value is assigned to the combination pattern corresponding to the I / V curve. Thereby, as shown in FIG. 3, the unit block B ₁
The weight value is determined for each of the 500 combination patterns assuming that the central atom I ₁ is carbon (C).

Therefore, subsequently, only the combination patterns which are equal to or larger than a preset threshold value (50 is set as the threshold value in this example) are selected (step 6). as a result,
Here, it is assumed that only the combination pattern of numbers 105 and 275 has been selected as the combination pattern having a weight equal to or greater than the threshold value. Here, for convenience,
For example, assuming that the central atom I ₁ is carbon (C), when a combination pattern of No. 105 and No. 275 is selected, it is expressed as I ₁ (105) C, I ₁ (275) C. And

[0020] Hydrogen central atom I ₁ of the unit block B ₁ (H), oxygen (O), in each assumption for nitrogen (N), running steps 4 6, respectively, selects a combination pattern (Step 7).

[0021] As a result, the unit blocks B ₁ around the atoms I _1, as shown in FIG. 4, the central atom I ₁ are two patterns in assuming carbon (C), hydrogen
It is assumed that three patterns are selected when (H) is assumed, three patterns are assumed when oxygen (O) is assumed, and two patterns are assumed when nitrogen (N) is assumed. . Therefore, this unit blocks B ₁ represents,
This means that a total of ten combination patterns have been selected as having a weight value equal to or greater than a certain threshold value (50 in this example).

Next, returning to step 3, the remaining atoms I ₂ to I ₂ other than the central atom I ₁ included in the first unit block B ₁ are obtained.
For I ₉ , a new unit block is set with each of the atoms I _{2 to} I ₉ as central atoms, and Steps 3 to 7 are repeated (Step 8).

For example, when attention is paid to I ₂ among the atoms included in the first unit block B ₁ , a unit block B ₂ having this as the central atom I ₂ is newly set and included in this unit block B _2. Steps 3 to 7 are repeated for the atoms I ₂ , I ₁ , I ₃ , I ₉ , I ₁₀ to ₁₄ .
As a result, as shown in FIG. 4, the central atom I ₂ carbon
Assuming four patterns when assuming (C), two patterns assuming hydrogen (H), one pattern assuming oxygen (O), and nitrogen (N) Each time one pattern is elected,
This unit block B ₂ would have been elected a total of eight combination patterns as having more weight value (50 in this example) a certain threshold. Then, the above processing is similarly performed for the remaining atoms I _{3 to} I ₉ included in the first unit block B ₁ .

Subsequently, for each of the selected combination patterns shown in FIG.
₁ performs matching based on the (step 9).

For example, one combination pattern I ₁ (105) C of the first unit block B ₁ and the unit block B ₂
In comparison with one combination pattern I ₂ (7) H of the pattern I ₁ (105) C, the central atom I ₁ is carbon (C) and the peripheral atom I ₂ is hydrogen (H ),
If both I ₃ and I ₉ are oxygen (O), the pattern I
₂ (7) H has both patterns B ₁ if its central atom I ₂ is hydrogen (H) and its surrounding atoms I ₁ are carbon (C), and both I ₃ and I ₉ are oxygen (O). , B ₂ will match.

As described above, the central atom I ₁ and its peripheral atoms I ₁ are selected from the combination patterns (10 types exist in this example) of each atom of the unit block B ₁ set first.
The combination relationship between the ₂ ~I ₉ selects one of the combination pattern that satisfies all (step 10).

On the other hand, in step 10, if the match around the combination patterns for the first unit block B ₁ is not fully obtained, the central atom I ₁ and its peripheral atoms I ₂ ~I ₉ shown in FIG. 4 The pattern having the largest weight value is selected from the combination patterns at the center (step 11).

For example, in FIG. 4, I ₂ (106) C
Is the maximum, this combination pattern is forcibly adopted. Accordingly, I ₁ , I except I ₂
Each atom of the ₃ ~I ₉ is determined.

Next, a corresponding color is assigned to each atom forming one combination pattern selected as described above (step 12).

For example, as shown in FIG. 5, carbon (C) is colored black, hydrogen (H) is white, oxygen (O) is red, and nitrogen (N) is blue.

The above steps 3 to 12 are performed as follows:
The repetition is performed over a necessary display area (step 13), whereby the S of the organic material colored according to each element is determined.
A TM image will be obtained.

In step 6, each of the atoms I ₁ to I ₁
If the threshold value for selecting a combination pattern centering on I ₉ is set low, it takes time for pattern matching in step 9 but the probability of matching increases, so the threshold value is sequentially increased as necessary. You may make it lower.

Step 6 is omitted and all the combination patterns and their weight values are stored regardless of the magnitude of the weight value. At step 9, the combination pattern centering on each of the atoms I _{1 to} I ₉ is stored. When performing matching, all coexisting combination patterns are selected, the maximum value of the result of adding (or multiplying) each weight value of each selected combination pattern is obtained, and a unit block B indicating the maximum value is obtained. ₁ of one pattern may be adopted as an optimal combination pattern.

[0034]

According to the present invention, the names of the elements are identified in the STM image of the organic material, and a color-coded display corresponding to each element is performed, so that the structure and structure of the compound can be easily grasped. Become.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a procedure of a drawing processing method using a scanning tunneling microscope according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the size of a unit block to be subjected to a drawing process.

FIG. 3 is an explanatory diagram showing a weighted state of a combination pattern of atoms.

FIG. 4 is an explanatory diagram showing a combination pattern of atoms selected for a unit block and having a predetermined threshold value or more.

FIG. 5 is an explanatory diagram showing a relationship between each atom finally identified for drawing and each color associated with each atom.

[Explanation of symbols]

B, B ₁ , B ₂ ... Unit block, I _{1 to} I ₉ , I _{10 to} I ₁₄ .
atom.

Claims (1)

(57) [Claims] 1. An STM image is taken of a sample of an organic material after an I / V curve of a central atom determined by a combination state of each atom included in a unit block of a certain region is taken in advance. After setting the block, a first step of measuring the I / V curve of the central atom of the unit block, and comparing the actually measured I / V curve with the pre-registered I / V curve to match the two curves And performing a second step of weighting the combination pattern of each atom contained in the unit block according to the degree of coincidence. Next, for all the other atoms contained in the unit block initially set, A new unit block centering on those atoms is newly set, and the first and second steps are repeated, and each combination having a large weighted value is set. One pattern that satisfies all the relations between the central atom and its surrounding atoms from the combination pattern of each atom of the unit block set first by performing matching based on the unit block set first A method for drawing an organic material using a scanning tunneling microscope, wherein a pattern is selected, and a corresponding color is assigned to each atom constituting one selected combination pattern.