JPH11183251A - Spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an energy-absorbance spectrum without performing any troublesome operation. SOLUTION: An energy/dispersion angle converting section 23 finds the dispersion angles for energy step widths. A pulse signal generating section 22 finds the number of driving pulse signals required for finding the dispersion angles, and only sends the found number of pulses to a stepping motor 112. As a result, a diffraction grating 111 is rotated by energy step widths and monochromatic light having the wavelength corresponding to the rotation is taken out from the grating 111.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrophotometer using ultraviolet visible light or infrared light.

[0002]

2. Description of the Related Art FIG. 3 is a schematic diagram showing an example of a general ultraviolet-visible spectrophotometer. Light emitted from a light source 10 such as a deuterium lamp or a tungsten iodine lamp contains various wavelengths, and a monochromatic light having a predetermined wavelength is extracted as measurement light by a spectroscope 11. This measurement light is applied to the sample cell 12 filled with the sample solution, and when passing through the sample cell 12, light having a wavelength specific to the sample is absorbed. The transmitted light is detected by the photodetector 13, and the signal processor 14 calculates the absorbance and the transmittance based on the detection signal.

[0003] The spectroscope 11 includes a diffraction grating 111 and a stepping motor 112 for rotating the diffraction grating 111 within a predetermined angle range. When the angle of the grating surface with respect to the light incident on the diffraction grating 111 changes, the wavelength of the monochromatic light taken out changes. Therefore, the wavelength λ of the measurement light and the angle of the diffraction grating 111 (hereinafter referred to as “dispersion angle”) are predetermined. Have a relationship. Further, since the rotation angle and the dispersion angle of the rotor of the stepping motor 112 are mechanically determined,
The number of drive pulse signals sent to the stepping motor 112 and the dispersion angle have a predetermined relationship. Therefore, the control unit 20
Performs a predetermined wavelength scan by sequentially transmitting to the stepping motor 112 a number of drive pulse signals determined in accordance with the wavelength operation range and the wavelength step width designated by the measurer using the operation unit 16. be able to.
As a result of such wavelength scanning, the signal processing unit 14 obtains the absorbance and the transmittance for each wavelength step. Accordingly, the horizontal axis and the vertical axis as shown in FIG. Spectrum) can be created.

[0004]

The absorption of ultraviolet and visible light as described above is based on the fact that the bond electrons in the ground state in the sample molecule are converted to light energy (E = hc / λ, h: Planck's constant,
c: the speed of light) and the transition to the excited state. For this reason, for example, when analyzing an electronic state or a three-dimensional structure of a semiconductor, a polymer compound, or the like, attention is often paid to the energy of the band gap and the binding energy instead of the wavelength. However, in a spectrum whose wavelength is represented on the horizontal axis as shown in FIG. 4A, it is difficult to immediately recognize or determine the correspondence between the energy and the absorbance.

Therefore, when such an analysis is performed, a configuration may be adopted in which a wavelength / energy conversion processing unit 15 is provided at a subsequent stage of the signal processing unit 14 as shown in FIG. The wavelength / energy conversion processing unit 15 converts the spectrum data obtained for each wavelength as described above into an energy E (unit e).
V) is calculated, and a spectrum with energy E on the horizontal axis is created as shown in FIG. However, in such a configuration, the measurer once sets the wavelength
After performing the operation of acquiring the absorbance spectrum, it was necessary to instruct the operation unit 16 to perform a process for converting the wavelength axis into the energy axis. Therefore, the operation is troublesome especially when measuring a plurality of samples.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an object to directly convert a spectrum having a unit other than wavelength, such as energy, frequency, and wave number, as a horizontal axis, if necessary. It is to provide a spectrophotometer that can be obtained.

[0007]

Means for Solving the Problems A spectrophotometer according to the present invention made to solve the above-mentioned problems comprises: a) a light source; and b) light of a specific wavelength by dispersing the wavelength of light emitted from the light source. Spectroscopic means for taking out and irradiating the sample; c) light detecting means for detecting transmitted light or reflected light of the sample; d) scanning in the wavelength direction with reference to a predetermined unit other than a wavelength having a specific relationship with the wavelength. Control means for controlling the spectroscopic means to be performed; and e) signal processing means for generating a spectrum having the predetermined unit as a horizontal axis based on the detection signal obtained by the light detection means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For example, the above-mentioned spectral means includes a wavelength dispersion element such as a diffraction grating or a prism and a driving means for mechanically rotating the element. In this configuration, the wavelength of the monochromatic light, which is the outgoing light, changes when the driving unit changes the angle of the element surface of the wavelength dispersion element with respect to the incident light. In a conventional spectrophotometer, driving means is controlled so that an element surface angle corresponding to the wavelength is obtained in order to perform wavelength scanning with a predetermined wavelength step width.

On the other hand, the control means of the spectrophotometer according to the present invention uses a predetermined unit other than the wavelength having a specific relationship with the wavelength, for example, the energy, the frequency, the wave number, etc., as a reference, and the step width of the predetermined unit. Thus, scanning in the wavelength direction is performed. That is, for example, the element surface angle is calculated so that monochromatic light having a wavelength corresponding to the energy for each predetermined energy step width is sequentially obtained, and the driving means is controlled so that the wavelength dispersion element is sequentially rotated by that angle. As a result, a detection signal for each step width of a predetermined unit is obtained from the light detection means, and the signal processing means creates a spectrum with the predetermined unit on the horizontal axis and absorbance, transmittance, and the like on the vertical axis.

[0010]

As described above, according to the spectrophotometer of the present invention, it is possible to directly obtain a spectrum having a specific relationship with the wavelength and having the energy, frequency, wave number and the like as the horizontal axis, if necessary. it can. For this reason, since it is not necessary to once acquire a spectrum having the wavelength on the horizontal axis as in the related art, the operation is extremely simplified, and the measurement efficiency is improved especially when a plurality of samples are measured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the spectrophotometer according to the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a main part of the spectrophotometer according to the present embodiment. In the spectrophotometer according to this embodiment, the control unit 20 includes a scan control unit 21, a pulse signal generation unit 22, and an energy / dispersion angle conversion unit 23. As a result, an absorption spectrum having the energy E as the horizontal axis can be directly obtained in the signal processing unit 14 as described later.

First, the operating principle of the spectrophotometer of the present invention will be described with reference to FIG. Incident optical axis A for diffraction grating 111
Angle between the light beam and the output optical axis B is 2k, the bisector of the angle is L, the normal to the grating surface of the diffraction grating 111 is P, and the bisector L
And the normal P, the angle λ of the emitted light is given by the following equation (1). λ = 2d / m · cosk · sin θ (1) where m is the order of the diffracted light, and d is the grating interval of the diffraction grating 111. Since k, m and d are constants determined by the design of the optical system, the relationship between the wavelength λ and the angle θ can be expressed by the following equation (2) using the constant C. λ = C · sinθ… (2)

On the other hand, there is a relationship as shown in equation (3) between the wavelength λ and the energy E (eV). E = {1 / (8.0546 · λ)} × 10 ¹³ (3) Accordingly, from the equations (2) and (3), the relationship between the energy E and the angle θ is expressed by the following equation using a constant C ′. It can be expressed as in equation (4). E = {1 / (8.06546 · C · sin θ)} × 10 ¹³ = C ′ / sin θ (4) Based on this relationship, a dispersion angle with respect to a predetermined energy can be obtained.

The energy / dispersion angle conversion unit 23 may be configured to cause the CPU to execute software including the above-described calculation formulas, or the energy / dispersion angle conversion unit 23 may calculate the correspondence between the energy and the dispersion angle by the formula (4). It is also possible to adopt a configuration in which the value is calculated in advance and stored in a ROM or the like, and when the value of the energy E is input, the variance angle can be obtained as an output.

Returning to FIG. 1, the operation of the spectrophotometer having the above configuration will be described. The measurer can use the operation unit 16 (for example, a keyboard or the like) to scan the energy step width (for example, 0.
05 eV) and the energy range to be scanned, the energy / dispersion angle conversion unit 23 obtains the dispersion angle corresponding to the minimum or maximum energy value within the designated energy range.
The pulse signal generation unit 22 calculates a variance angle /
The required number of drive pulse signals is obtained based on the correspondence between the number of drive pulse signals, and the number of drive pulse signals is transmitted to the stepping motor 112. Accordingly, the rotor of the stepping motor 112 rotates from the home position (initial position) according to the number of drive pulse signals, for example, and the angle of the diffraction grating 111 changes.

The scanning control unit 21 sends a signal acquisition instruction signal to the signal processing unit 14, whereby the signal processing unit 14 acquires a detection signal from the photodetector 13 after the diffraction grating 111 has rotated by a predetermined angle and stopped. I do. Then, the absorbance is calculated based on the detection signal. Thereafter, the scanning control unit 21 sends a drive instruction signal to the pulse signal generation unit 22.
Accordingly, the pulse signal generation unit 22 obtains the number of drive pulse signals corresponding to the variance angle corresponding to the energy value separated by a predetermined energy step width from the minimum or maximum energy value within the designated energy range, and The driving pulse signal is transmitted to the stepping motor 112. Signal processing unit 1
4 acquires again the detection signal after the diffraction grating 111 rotates.

By repeating such processing, the diffraction grating 111 rotates sequentially with an angle corresponding to the designated energy step width, and the signal processing unit 14 calculates the absorbance based on the detection signal acquired for each rotation. . As a result, a spectrum having energy E as the horizontal axis is created as shown in FIG.

The spectrophotometer according to the present invention has another unit having a specific relationship with the wavelength, for example, the frequency ν (= c / c).
Obviously, the present invention can be applied to a case where a spectrum is created with the horizontal axis of (λ, c: speed of light) and the wave number 1 / λ.
Further, a configuration using a wavelength dispersion element other than the diffraction grating such as a prism, for example, may be used as the spectroscope.

Further, the above embodiment is merely an example, and it is apparent that changes and modifications can be appropriately made within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of a spectrophotometer according to the present invention.

FIG. 2 is a diagram illustrating the principle of the spectrophotometer of the present invention.

FIG. 3 is a schematic configuration diagram of a conventional general spectrophotometer.

FIG. 4 shows an example of an absorption spectrum.

[Explanation of symbols]

Reference Signs List 10 light source 11 spectroscope 111 diffraction grating 112 motor 12 sample cell 13 photodetector 14 signal processing unit 20 control unit 21 scanning control unit 22 pulse signal generation unit 23 energy / dispersion angle conversion Department

Claims (1)

[Claims] A) a light source; b) spectral means for dispersing light emitted from the light source to extract light of a specific wavelength and irradiating the sample with a light; c) detecting transmitted light or reflected light of the sample. Light detection means, d) control means for controlling the spectroscopic means to perform scanning in the wavelength direction with reference to a predetermined unit other than a wavelength having a specific relationship with the wavelength, e) a detection signal obtained by the light detection means And a signal processing means for generating a spectrum having the predetermined unit as a horizontal axis based on the following.