JPH08233728A - Microscopic total reflection absorption spectrum measuring apparatus - Google Patents

Abstract

PURPOSE: To obtain a microscopic total reflection absorption spectrum measuring apparatus which can measure even a micro part on a sample with high sensitivity comparable to that of high reflection absorption spectroscopy(RAS). CONSTITUTION: The microscopic total reflection absorption spectrum measuring apparatus comprises a total reflection objective optical system (Cassefrain mirror) including a main concave mirror 2 and a sub-convex mirror 3, and a metal plate 8 applied tightly to the rear of a sample 7 being pressed by a hemispheric ATR (total reflection absorption spectrum measuring method) prism 4 centered at the focus point of the optical system. At the time of measurement, the ATR prism 4 is brought into tight contact, at an appropriate pressure, with the sample 7 placed on the metal plate 8. Consequently, the light entering into the metal plate (conductor) 8 through the sample layer produces a steady wave having amplitude corresponding to the incident angle. Since interaction with the sample 7 is enhanced, the absorption of the sample 7 is amplified thus contributing to the enhancement of the sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a total reflection absorption spectrum measuring device using a reflection microscope system.

[0002]

2. Description of the Related Art Total reflection absorption spectrum measurement method (ATR)
Is an ATR prism made of a high-refractive-index material that allows infrared light to come into close contact with the surface of the sample. A method of measuring the absorption characteristics of a sample by detecting the absorption of light that is incident and totally reflected by the sample. A device using a microscope system is used.

[0003]

However, in the conventional total internal reflection absorption spectrum measuring apparatus, only a minute portion of the sample with which the ATR prism is in close contact is a measurement target.
There was a problem that high-sensitivity measurement could not be performed. On the other hand, there is a high-sensitivity reflection method (RAS) as a method for measuring a metal thin film with high sensitivity, but the RAS method is difficult to apply to the measurement of a minute portion due to a large incident angle, and a grid polarizer is used As a result, the amount of light was greatly attenuated, and it was not suitable for the measurement of a minute portion using an infrared reflection microscope. It is an object of the present invention to obtain a microscopic total reflection absorption spectrum measuring device capable of performing high-sensitivity measurement comparable to the high-sensitivity reflection method (RAS) even when measuring a minute portion of a sample.

[0004]

In order to achieve the above object, a microscopic total reflection absorption spectrum measuring apparatus of the present invention has a reflective objective optical system composed of a concave primary mirror and a convex secondary mirror. Metal hemispherical AT centered on the focal point of
A metal plate is placed in close contact with the back surface of the sample to which the R prism is pressed.

[0005]

In the total reflection absorption spectrum measuring apparatus configured as described above, the ATR prism, the sample and the metal plate are arranged at the time of measurement, and the metal ATR prism is brought into close contact with the sample on the metal with appropriate strength. . As a result, the light transmitted through the sample layer and incident on the metal plate (conductor) becomes a standing wave with an amplitude according to the incident angle, the interaction with the sample becomes large, and the light absorption by the sample is amplified, which increases the sensitivity. Contribute to.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A microscopic total reflection absorption spectrum measuring apparatus of the present invention will be described below with reference to the drawings. In FIG. 1, a reflective objective optical system is a concave primary mirror 2 having a hole in the center,
Cassegrain reflection objective mirror 1 including the concave primary mirror 1 and the convex secondary mirror 3 in the peripheral portion of the objective hemispherical objective lens 5 that is coaxial.
At the tip of the Cassegrain mirror 1, a hemispherical AT made of a metal, for example, germanium (Ge), whose center is the condensing point is used.
The R prism 4 is attached. Further, on the optical axis of the Cassegrain mirror 1, an ATR measurement aperture 6 having a ring-shaped aperture is arranged so that the centers thereof coincide with each other and the peripheral light is transmitted. Therefore, of the measurement light (monochromatic light) emitted from the spectroscope (not shown), the peripheral secondary light on the right side in the figure is irradiated onto the convex secondary mirror 3 by the aperture 6. The objective lens 5 itself is used when a visual aperture (not shown) having a circular opening for transmitting paraxial light is arranged on the optical axis of the Cassegrain mirror 1 to visually observe a sample with an objective optical system. .

The sample 7 is brought into pressure contact with the lower surface of the ATR prism 4, and a metal plate 8 (conductor) is arranged on the bottom surface of the sample 7 and brought into close contact with the rear surface of the sample. That is, at the time of measurement, the sample is GeAT
The R prism 4, the sample 7, and the metal plate (conductor) 8 are arranged.

At the time of ATR measurement, the ambient light transmitted through the ATR measurement aperture 6 is applied to the convex secondary mirror 3, and only the light having the incident angle required for the ATR measurement is incident on the ATR prism 4 via the concave primary mirror 2. ATR prism 4 and sample 7
Totally reflects on the contact surface of. This totally reflected light again enters the Cassegrain mirror 1 (convex sub-mirror 3 and concave main mirror 2) and passes through the Cassegrain mirror 1 by the aperture 6 as ambient light on the left side in the figure by an MCT detector (not shown). To be detected. At this time, the light incident on the ATR prism 4 reaches the metal plate 8 through the sample layer and becomes a standing wave having an amplitude corresponding to the incident angle, which increases the interaction with the sample and absorbs light by the sample. As a result, the measurement sensitivity is significantly increased.

For example, for the same sample, the AT of the present invention
FIG. 2 shows an absorption spectrum as a result of comparative measurement with the arrangement of the R prism-sample-metal plate and the arrangement of the conventional ATR prism-sample. Apparently the ATR prism of the present invention-Sample-
With the arrangement of the metal plate, a sensitivity increase of several times to several tens of times is obtained. Further, when the sample is a thin film composed of a very thin number of molecular layers such as an LB film, as shown in FIG.
0 °, combined use of polarizer, pyroelectric detector, 8 cm ^-1 , 100 times,
2.8 mm / sec, 1c under automatic gain measurement conditions
The result of measuring the sample area of mφ by the high sensitivity reflection method (RAS) and the MCT detector, 8 cm ⁻¹ , 100 times, 9 mm / s
Under the measurement conditions of ec and automatic gain, a sample area of a very small portion of 100 μmφ was measured by the microscopic total reflection absorption spectrum measuring apparatus of the present invention, and the absorption spectra were almost the same.

The sample and the metal plate are placed on a sample stage (not shown) of an infrared reflection microscope, which can be easily moved and set. Mapping measurement by infrared absorption spectrum is also possible by linking the measurement.

[0011]

Since the present invention is configured as described above, it is possible to obtain an infrared absorption spectrum similar to that of the high sensitivity reflection method (RAS) even in the measurement of a very small sample portion. it can.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram (data) showing an example of measurement comparison between the device of one embodiment of the present invention and the conventional device.

FIG. 3 is a diagram (data) showing a comparative example of the measurement result of the device of one embodiment of the present invention and the measurement result by the different high-sensitivity reflection method.
Is.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cassegrain reflection objective mirror 2 ... Concave primary mirror 3 ... Convex secondary mirror 4 ... ATR prism 5 ... Objective lens 6 ... Aperture 7 ... Sample 8 ... Metal plate

Claims (1)

[Claims] 1. A microscopic total reflection absorption spectrum measuring apparatus having a reflective objective optical system composed of a concave primary mirror and a convex secondary mirror, and equipped with a metal hemispherical ATR prism centered on a focal point of the optical system. 2. A micro total reflection absorption spectrum measuring apparatus, characterized in that a metal plate is placed in close contact with the back surface of the sample to which the ATR prism is pressed.