JPS6013455B2 - photoacoustic analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoacoustic analyzer, and more particularly, a detector for detecting light is installed in a sample chamber, and a sample is analyzed from the output of the photodetector and the output of the photoacoustic effect. This article relates to a photoacoustic analyzer that enables

Generally, when a material is irradiated with light energy, a portion of the irradiated light energy is absorbed by the material, and a portion of this absorbed light energy is converted into thermal energy.

Moreover, since a substance has a unique light absorption spectrum corresponding to certain conditions, the amount of absorbed light energy, that is, the amount of conversion into thermal energy, also takes on a unique value depending on the substance. In addition, the converted thermal energy increases the temperature of the atmospheric gas surrounding the substance and increases the pressure of the atmospheric gas, so it is possible to analyze the substance by detecting this change in pressure. Become. Also, when some materials are irradiated with electromagnetic waves of a certain wavelength, they absorb the electromagnetic waves and re-emit electromagnetic waves of the same wavelength or longer wavelength, and this re-emission is approximately 10
-When it occurs within 9 seconds, it becomes a poppy, a light.

Since the magnitude of this fluorescent light exhibits a unique value depending on the substance, it is possible to analyze the sample by detecting the fluorescent light re-emitted from the sample. Incidentally, when a substance is irradiated with light, the absorbed light energy is converted into thermal energy, electrical energy, chemical bond energy, excitation energy, etc., and the law of conservation of energy holds true between these energies. Furthermore, the light-related properties of substances include:
There are many properties such as thermal properties, electrical properties, optical properties, etc., and these properties are organically related to each other, and different properties such as thermal properties and optical properties can be combined under the same conditions. Although it is often necessary to measure these properties simultaneously, heretofore it has been inconvenient to measure these properties almost individually. Therefore, the purpose of the present invention is to simultaneously detect the photoacoustic effect output obtained by irradiating light onto a sample housed in a sample chamber and the electrical output obtained by photoelectrically converting the poppy light re-emitted from the sample. The purpose of the present invention is to provide a photoacoustic analyzer that can perform the following functions.

Therefore, the present invention achieves the above object by transporting a sample chamber filled with gas and a reference chamber through a gas passage, and incorporating a thermal flow meter type detection element on this gas passage. A thermal flowmeter measures the gas flow in the gas passage caused by the thermal expansion of the gas in the sample chamber caused by the sample by intermittently irradiating a sample placed in the chamber with light at a constant frequency. In a system in which the sample is analyzed by detection with a shape detection element: A ray photodetector is built into the sample chamber, and the ray light re-emitted from the sample is converted into an electric output and photoacoustic. The feature is that the sample can be analyzed based on the effect output.

An embodiment of the photoacoustic analyzer according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the photoacoustic analyzer according to the present invention, and the symbol A in the figure indicates a detector that analyzes a sample using the photoacoustic effect. A light intermittent chopper B is provided immediately in front of the detector A, and is capable of intermittently irradiating the sample within the detector A with light at a constant frequency.

The photoacoustic effect output signal a from the detector A is sent to an operational amplifier C, where it is operationally amplified, and then sent to an instruction recorder D, where it is indicated and recorded. In addition, the above-mentioned light intermittent chopper B
A signal from the above is applied to the operational amplifier C as a signal b indicating intermittent light. On the other hand, the symbol E indicates a poppy that is re-radiated from the sample, a poppy that detects light, and a photodetector, and the electrical output e from this detector is sent to an operational amplifier F, where it is operationally amplified, and then given an indication. It is sent to recorder D and the instructions are recorded.

Next, the details of the structure of the detector A, which constitutes the main part of the present invention, will be explained with reference to FIG.

In FIG. 2, the detector, generally designated by the symbol A, has a detector main body 1, in which a sample chamber 3 for accommodating a sample 2 and a reference chamber 4 are provided. This sample chamber 3
and the reference chamber 4 are separated by a gas passage 5.

These sample chamber 3 and reference chamber 4 are filled with, for example, air or a gas such as nitrogen or helium. The sample 2 may be any sample that has the property of absorbing electromagnetic waves when irradiated with electromagnetic waves of a certain wavelength, rejecting electromagnetic waves of the same wavelength or longer wavelength, and re-radiating them as light.

A light transmitting window 6 is disposed on the upper surface of the sample chamber 3 in an airtight manner, and from above the light transmitting window 6, light from a light source such as a Xe lamp is passed through a spectrometer to become monochromatic light. Further, the sample chamber 3 is irradiated with intermittent light of a constant frequency by the light intermittent chopper B.

On the other hand, on the lower surface of the sample chamber 3, a sample stage 8, which is kept airtight via a sealing element 7 such as an O-ring, is removably installed.

A thermal flow meter type detection element 9 is attached to the outlet side of the gas passage 5, and this detection element 9 is activated at the same period as the period of light interruption by the light interruption chopper B, as will be described later. Detects periodic pressure fluctuations and connects the lead wire 10.
outputs an alternating current electrical signal to the outside through the

The thermal flow meter type detection element 9 functions as a type of hot wire anemometer composed of two Ni lattices with equal resistance-temperature characteristics, and the temperature of the gas in the sample chamber 3 is When the resistance changes, a gas flow occurs in the gas passage 5, thereby changing the resistance, and this resistance change can be extracted as a voltage output.

Therefore, according to this thermal flow meter type detection element 9, the vibration of the gas caused between the sample chamber 3 and the reference chamber 4 is detected as an alternating current electrical signal. This electrical signal is sent to the operational amplifier C shown in FIG. 1 as a sound effect output,
It is amplified after being subjected to arithmetic processing together with the signal indicating the wavelength and intensity of the optical signal from the optical chopper B. According to the present invention, the poppy is placed inside the detector body 1 above the light transmission window 6.
A photodetector 11 is arranged. This poppy, photodetector 1
1 preferably uses a photoelectric conversion element that converts poppy light re-radiated from the sample 2 when the sample 2 in the sample chamber 3 is irradiated with light energy into an electrical signal. Since the photoacoustic analyzer according to the present invention is constructed as described above, the sample 2 to be analyzed is now housed in the sample chamber 3 of the detector A, and the light from the light source of the Xe lamp is passed through the spectrometer. The sample 2 is irradiated with monochromatic light and intermittent light of a constant frequency by the light intermittent chopper B through the light transmission window 6.

Then, part of the irradiated light energy is absorbed by the sample 2, and part of this light energy is converted into heat energy, which increases the temperature of the atmospheric gas in the sample 2 and causes thermal expansion of the gas in the sample chamber 3. cause The thermal expansion of this gas is
increase the pressure of the atmospheric gas. This pressure increase is caused at the same period as the light intermittent period, and is detected by the thermal flow meter type detection element 9 as described above, and is detected as an alternating current electric signal. This electrical signal is sent to the operational amplifier C shown in Figure 1 as an indicator of the acoustic effect output, where it is amplified after being subjected to arithmetic processing together with the signal indicating the wavelength and intensity of the optical signal from the optically intermittent chopper B. Ru. The amplified signal is then sent to the instruction recorder D, where the result is indicated and recorded. On the other hand, when the sample 2 in the sample chamber 3 is irradiated with light energy, the light re-emitted from the sample 2 is detected by the photodetector 11, and its electrical output signal e is sent to the operational amplifier F' After being sent and operationally amplified, the amplified signal f is sent to an instruction recorder D, where the result is indicated and recorded.

3 and 4 respectively show embodiments in which the structure of the detector A is different.

Of these, the one shown in FIG. 3 is an example in which a sample chamber 3 and a reference chamber 4 are stacked vertically, and a light transmission window 6 is arranged at the boundary between the two chambers, and the space between the two chambers is They are connected by a gas passage 5. In this type of detector, the light detector 11 may be disposed within the main body 1 in an extension of the light re-emitted from the sample 2 and traveling through the light transmission window 6. According to the configuration shown in FIG. 3, the gas filled in the reference chamber 4 and sample chamber 3 also absorbs a part of the irradiated light energy, but at this time, as monochromatic light, the wavelength and intensity are equal, Furthermore, if the reference chamber 4 and the sample chamber 3 are selected to have the same transmission length, the absorption of the light energy by the gas in the reference chamber 4 and the sample chamber 3 will occur in the same amount and will be canceled out.

Therefore, a pressure difference is generated between the sample chamber 3 and the reference chamber 4 due only to the thermal expansion and expansion of the gas based on the thermal energy of the sample, and the gas flows from the sample chamber 3 to the reference chamber 4. On the other hand, what is shown in FIG. 4 is an example in which the reference chamber 4 has the same structure as the sample chamber 3, and both chambers are connected by a gas passage 5. For example, a measurement sample 2A is set in the sample chamber 3. , and reference chamber 4
A reference sample 2B is set inside the chamber, light energy is irradiated onto the samples 2A and 2B under the same conditions, and the photoacoustic effect output is detected based on the difference in the amount of light absorption between the two.

In this type of detector, each sample 2A, 2B
A photodetector 11 that detects poppy light re-emitted from the
It is sufficient to arrange A and 11B. FIG. 5 shows a cross-sectional view of another embodiment of the invention.

A is the analyzer of the present invention. This analyzer A is a closed container AI
and A2 are juxtaposed. The closed containers AI and A2 each consist of a sample chamber and a reference chamber. 3,30' is the sample room. Sample room 3,301
Samples 2 and 20 to be analyzed are placed here, and light transmission windows 6 and 60 are provided for irradiating these samples 2 and 20' with light energy. The samples 2 and 20 are arranged in the sample chambers 3 and 30 by being placed on the sample stands 8 and 80, respectively, and can be replaced by removing the sample stands 8 and 80. Sample stands 8 and 80 are the fifth
As shown in the figure, both may be formed integrally,
Alternatively, it may be a separate item (not shown). 7,7
0 is a sealing element, for example an 0 ring.

4 and 40 are reference chambers.

The reference chambers 4 and 40 are connected to the sample chambers 3 and 30 via passages 5 and 50, respectively, so that the sample chamber 3 and the reference chamber 4 and the sample chamber 30 and the reference chamber 4 each have one flow. Closed containers AI and A2 are formed.
The airtight containers AI and A2 are each filled with air or a gas such as nitrogen or helium. Furthermore, the sample chamber 3, the reference chamber 4, and the sample chamber 3
Thermal flow meter type detection elements 14 and 140 are installed at arbitrary locations in the passages 5 and 50 of the reference chamber 40 and the reference chamber 40, respectively.
During analysis, the analyzer A of the present invention constructed in this manner simultaneously and intermittently irradiates the samples 2 and 201 with light energy having the same wavelength and energy through the light transmission windows 6 and 60, respectively. Note that this light energy may be applied alternately for a certain period of time. Therefore, the output of each thermal flow meter type detection element 14, 140 is sum, quotient, difference,
Arithmetic processing such as multiplication is performed to produce the final output. Moreover, in this detector A, the poppy that is re-radiated from the samples 2 and 20, the poppy that detects the light, and the photodetector 11 and 110
is provided. Note that 10,100 is a lead. As is clear from the above description, according to the present invention, a sample to be analyzed housed in a sample chamber is intermittently irradiated with light at a constant frequency, and the resulting photoacoustic effect output is converted into heat. Since the flow meter type detection element detects the light that is re-emitted from the sample, and the photodetector detects it at the same time, it is possible to simultaneously measure the thermal properties and optical properties of the sample due to light absorption. As a result, the capability and scope of use of the analyzer can be expanded.

Furthermore, it is also possible to simultaneously examine the relationship between the photoacoustic effect output and the light output when a specific sample is irradiated with light energy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the photoacoustic analyzer according to the present invention, and FIG. 2 is a longitudinal sectional view showing the structure of the detector.
3 to 5 are longitudinal sectional views showing other structures of the detector. In particular, in Fig. 5, (A) is a longitudinal cross-sectional view, (B)
is a plan view. A...Detector, B...Optical chopper, C...Operation amplifier, D...Instruction recorder, E...
Poppy, photodetector, F... operational amplifier, 1... main body,
2...Sample, 3...Sample chamber, 4...Reference chamber, 5...
Gas passageway, 6...light transmission window, 8...sample stage, 9...thermal flow meter type detection element, 1 1...fluorescence detector. 1 drawing, 2 drawings *Yugao 9 drawings, 9 drawings

Claims (1)

[Scope of Claims] 1. A sample chamber filled with gas and a reference chamber are communicated through a gas passage, and a thermal flow meter type detection element is incorporated in this gas passage, and a sample chamber placed in the sample chamber is The sample is analyzed by irradiating light energy intermittently at a constant frequency and detecting the gas flow in the gas passage caused by this with the thermal flow meter type detection element. characterized in that a fluorescence detector is incorporated in the sample chamber, and the sample can be analyzed from the electrical output and photoacoustic effect output obtained by photoelectrically converting the fluorescence re-emitted from the sample. Photoacoustic analyzer. 2. In the analyzer according to claim 1, a sample is also placed in the reference chamber, and the sample is irradiated with light energy equal to the light energy irradiated to the sample in the sample chamber, either simultaneously or alternately and intermittently. The gas flow in the gas passage caused by each sample is detected by a thermal flowmeter type detection element, and the above-mentioned In addition to detecting the difference in photoacoustic effect output between samples, a fluorescence detector is installed in the reference chamber to detect the electrical output based on the fluorescence re-emitted from the sample in the reference chamber and the re-emission from the sample in the sample chamber. A photoacoustic analyzer that detects a difference in electrical output based on fluorescent light.