JPS589363B2 - How to measure the thickness of a thin film on a solid plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the thickness of a monomolecular film or a thin film similar thereto, and more particularly, to a method for measuring the thickness of a monomolecular film or a thin film similar thereto, and more specifically, it relates to a method for measuring the thickness of a monomolecular film or a thin film similar to the same, and more specifically, a method for measuring the thickness of a monomolecular film of a substance having luminescence ability, a part of a fluorescence quenching substance, A film whose thickness is to be measured is sandwiched between a surface monomolecular film consisting of a cadmium arachidate monolayer, and the relative fluorescence intensity of the quencher part and the cadmium arachidate part is measured, and from the ratio, it is determined that the thickness of the film is It relates to a method of measuring thickness.

Conventionally, in order to measure the thickness of thin films such as monomolecular films, the method of forming a monomolecular film on the water surface using the substance as a solution and measuring it has not always been satisfactory. Ta.

The present inventor forms a thin film such as a monomolecular film on a solid plate,
As a result of repeated research to develop a method that can accurately measure the thickness, a monomolecular film made of molecules with luminescence ability was layered on a solid plate, and a thin film for measuring the thickness was formed on top of this. After that, a surface monomolecular film consisting of a fluorescence quencher part and a cadmium arachidate part is layered on top of that, the relative fluorescence intensity of both parts is measured, and the ratio is taken to determine the thickness of the thin film. Based on this knowledge, we have completed the present invention.

That is, in the present invention, at least three monomolecular films of cadmium arachidate, cadmium stearate, or cadmium palmitate are accumulated on a solid plate, a monomolecular film of a fluorescent substance is overlaid on this, and the thickness is measured. After forming a thin film thereon, the thin film is covered with a surface monomolecular film consisting of a fluorescence quencher part and a cadmium arachidate part, and the relative fluorescence intensities of both parts are measured and the ratio is calculated. From the relationship between the relative fluorescence intensity ratio determined in advance and the distance between the fluorescent substance monolayer and the surface monolayer,
A method for measuring the thickness of a thin film on a solid plate is provided, the feature of which is determining the thickness of the thin film.

In the present invention, first, on a solid plate such as a glass plate,
At least three monolayers of cadmium arachidate, cadmium stearate, or cadmium palmitate are accumulated.

These monolayers usually contain 10 M to 10'M of arachidic acid, stearic acid or palmitic acid, respectively.
It can be formed by making an aqueous solution of chloroform and dropping it onto the surface of water containing cadmium ions and having a pH of 5 to 6.

These monomolecular films are produced using the Blodgett method (Blodgett's method), which is known as a method for producing cumulative films.
que), it can be transferred directly onto the solid plate from above the water surface, and the required number of layers can be stacked.

FIG. 1 shows a schematic diagram of a cadmium arachidic acid monolayer cumulative film (three layers) formed on a glass plate in this manner.

In the figure, the glass plate 2 indicated at 1 is a cadmium arachidic acid molecule.

In this case, the thickness of one monolayer of cadmium arachidate is 27 Å, so the thickness of three layers is 71 Å.

Next, one layer of a monomolecular film of a fluorescent material is deposited on top of this cumulative pattern.

For example, such a substance includes a dye such as a long-chain alkylated cyanine compound (hereinafter referred to as compound A) represented by the following formula.

This mixture and arachidic acid are mixed in a molar ratio of, for example, 1:20.
A 700 form solution (10-3 M) mixed with 700 forms a stable mixed monolayer on the water surface.

One layer of this monomolecular film is deposited on top of three layers of a cadmium arachidic acid monomolecular film by applying the Projet method.

Compound A has fluorescent properties, and in particular, when excited with light at the absorption maximum of 520, it emits strong fluorescence.

In this case, the fluorescent dye monolayer is at least 71 Å away from the glass plate, so it is usually 40 Å away.
Energy transfer, which is said to occur up to a distance of , does not occur between this monomolecular film and the glass plate, at least.

In other words, the fluorescence emitted by the monomolecular film is not quenched by the glass plate at all.

The monomolecular film of a fluorescent substance formed in this way is stacked with several monomolecular films of a compound whose molecular length is known, and then a monomolecular film of a fluorescent quenching substance is further accumulated on top of the monomolecular film of a compound whose molecular length is known. Form a surface monomolecular film consisting of a cumulative part of a cadmium arachidic acid monomolecular film, and calculate the ratio of relative fluorescence intensities on the surface of both parts, and calculate the distance between the fluorescent monomolecular film and the surface layer. Find the relationship and graph it.

To explain this in more detail, first, before intervening a monomolecular film of known molecular length, the above-mentioned surface monomolecular film is formed directly on the monomolecular film of the fluorescent material without intervening it, Find the ratio of relative fluorescent intensities.

As this quencher, for example, a long-chain alkylated bipyridinium cation represented by the following formula (hereinafter referred to as compound B)
and cadmium arachidate in a molar ratio of 1:2.
A 10-3M chloroform solution of the above solution is dropped onto the water surface to form a stable monomolecular film.

This monolayer is then accumulated on half of the upper surface of the monolayer of fluorescent material using the projector method.

In the remaining half, a cadmium arachidic acid monolayer is accumulated by the Prodget method.

FIG. 2 is a schematic diagram of a glass plate on which a monomolecular film is formed on the surface in this manner. The molecular film 5 is a monomolecular film made of cadmium arachidate.

Long chain alkylated bipyridinium cations, such as compound B above, are extremely strong quenchers.

The relative fluorescence intensity of the dye monomolecular film in the part covered with the monomolecular film made of this quencher is ■, and the relative fluorescence intensity of the dye monomolecular film in the part covered with the cadmium arachidate monomolecular film is I∞. In this case, I=0.04
, ■∞=0.75 and I/I∞=0.067.

Next, as shown in FIG. 3, a monomolecular film 3 of a fluorescent substance,
Between the surface monolayer consisting of the quencher monolayer 4 and the cadmium arachidate monolayer 5, a cadmium palmitate monolayer, a cadmium stearate monolayer, or a cadmium arachidate monolayer of known molecular length is inserted. Create several types of membrane 6 with different numbers of layers (two layers in this figure), measure each ■ and ■∞, and calculate I/I∞.
seek.

In this way, the relationship between I/I∞ as the vertical axis and the distance d between the monomolecular film of the fluorescent material 3 and the monomolecular film of the quenching material 4 as the horizontal axis is shown in FIG. It is.

To measure the thickness of a thin film by the method of the present invention, the thin film is formed on the monomolecular film of the fluorescent substance, and the surface monomolecular film as described above is further formed on top of the monomolecular film of the fluorescent substance. Thereafter, the ratio I/I∞ of the relative intensity of fluorescence on the surface is determined, and d is determined from the above graph to determine the film thickness.

According to the method of the present invention, it is possible to easily measure not only the thickness of a monomolecular film but also the film thickness of a film in which several monomolecular films are accumulated.

Using this method, it is possible to accurately measure the thickness of the cumulative film on dye electrodes used in solar cells and the like.

Next, the present invention will be explained in more detail with reference to Examples.

EXAMPLE Three monomolecular films of cadmium arachidate were deposited on a glass plate by the Blodgett method.

Then, a monomolecular film of the compound A is deposited thereon also by Blodgett's method.

On the other hand, 10-3M of cholesterol is used to measure the thickness of the membrane.
A chloroform solution was prepared, and this was accumulated as a monomolecular film by Blodget on the monomolecular film of compound A, and this was used as a quenching substance. A surface monomolecular film consisting of a monomolecular film formed from a solution and a monomolecular film of cadmium arachidate was sandwiched, and the relative fluorescence intensity was measured, and ■/I∞ was determined to be 0.371.

When this value is referred to the graph of FIG. 4, it can be seen that the film thickness is 14A.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the state of the accumulated film on the glass plate, Figure 2
The figure is a schematic diagram showing a state in which a surface monomolecular film consisting of a monomolecular film of a fluorescent substance, a part of a quenching substance, and a part of cadmium arachidate is accumulated on the accumulated film. A schematic diagram showing a state in which two monolayers of cadmium arachidate are interposed between a monolayer of the fluorescent material and a surface monolayer. Figure 4 shows the cumulative film surface of Figure 3. 3 is a graph showing the relationship between the ratio of relative fluorescence intensity and the thickness of the intervening cumulative film of cadmium arachidate. Explanation of symbols 1... Glass plate, 2,5.6... Monomolecular film of cadmium arachidate, 3... Monomolecular film of fluorescent substance, 4... Monomolecular film of quenching substance .

Claims (1)

[Claims] 1. Accumulate at least three monomolecular films of cadmium arachidate, cadmium stearate, or cadmium palmitate on a solid plate, overlay a monomolecular film of a fluorescent substance on top of this, and then apply a thin film whose thickness is to be measured on top of this. After that, the thin film is covered with a surface monomolecular film consisting of a fluorescence quencher part and a cadmium arachidate part, and the relative fluorescence intensity of both parts is measured and the ratio is determined in advance. A thin film on a solid plate characterized in that the thickness of the thin film is determined from the relationship between the determined relative fluorescence intensity ratio and the distance between the fluorescent substance monolayer and the surface monolayer. How to measure thickness.