JP2011215117A - Emission spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an emission spectrophotometer for easily performing analysis at appropriate analysis accuracy and analysis sensitivity according to the type, state, and analysis purpose of a sample.SOLUTION: The emission spectrophotometer excites the solid sample S to emit light by discharge, wavelength-disperses the emission light with a spectrometer 20, and detects light of a specific wavelength. The emission spectrophotometer includes a sample holding means for holding the solid sample S, a condenser lens 14 that is arranged between the sample holding means and the spectrometer 20, condenses a part of the emission light, and introduces it to the spectrometer 20, a light shielding mask 15 arranged ahead of the condenser lens 14, and a mask driving means 16 for altering the angle formed by a surface to be analyzed of the solid sample S and the optical axis of the emission light entering the spectrometer 20 by moving the light shielding mask 15.

Description

  The present invention relates to an emission spectroscopic analyzer.

  In an emission spectroscopic analyzer, a solid sample, which is generally a metal or nonmetal, is given energy by arc discharge, spark discharge, or the like to evaporate and evaporate the sample, and the emitted light is introduced into a spectrometer for each element. A spectral line having a characteristic wavelength is extracted and detected (see, for example, Patent Document 1). In particular, an emission spectroscopic analyzer using a spark discharge as an excitation source is capable of highly accurate analysis. For example, in a production plant such as a steel material or a non-ferrous metal material, a composition analysis in a produced metal body is performed. Widely used.

  At the time of analysis by such an emission spectroscopic analyzer, a solid sample to be analyzed is set on a sample stand provided in the apparatus. The sample stand is generally made of a cast metal or ceramic, and a sample placement plate on which the sample is placed and an electrode bar for discharge are fixed on the sample stand. The sample mounting plate has an opening at the center, and a solid sample is mounted so as to cover the opening during analysis. The electrode rod is disposed below the sample mounting plate with its tip directed toward the center of the sample mounting plate. Therefore, at the time of analyzing the sample, the tip of the electrode rod and the lower surface of the sample (surface to be analyzed) face each other through the opening of the sample mounting plate.

Japanese Patent Laid-Open No. 2001-83096

  The sample stand is configured to hold the sample mounting plate tilted at a predetermined angle with respect to the light collecting axis of the spectrometer in order to direct light emitted by excitation light emission of the sample to the spectrometer. It has been conventionally known that the sensitivity and accuracy of analysis change depending on the angle. That is, as shown in FIG. 6A, when the inclination angle α of the sample mounting plate 72 with respect to the daylighting axis 71 of the spectrometer is made relatively small, light or vapor cloud from the sample itself that contributes to noise. As a result, it is difficult for a spectral line or the like that has received the interference to enter the spectroscope, so that a good measurement sensitivity can be obtained. However, on the other hand, it is easily affected by the surface state of the sample 73 and the measurement accuracy is lowered. . Conversely, as shown in FIG. 6B, when the inclination angle α of the sample mounting plate 72 with respect to the light collection axis 71 of the spectroscope is relatively increased, interference from light or a vapor cloud from the sample itself. However, the measurement sensitivity is reduced because the received spectral lines are likely to enter the spectroscope, but the measurement accuracy is improved because the spectral lines are not easily affected by the surface condition of the sample 73.

  The inclination angle of the sample mounting plate 72 optimum for analysis varies depending on the type of sample, the state of the sample, the purpose of analysis, and the like. However, as described above, the electrode rod 74 and the sample mounting plate 72 are fixed to the sample stand, and the inclination angle of the sample mounting plate 72 cannot be changed during analysis. Therefore, in the conventional emission spectroscopic analyzer, the sample mounting plate is set to an intermediate inclination angle, or the purpose of use of the apparatus is limited and the inclination angle is set accordingly.

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to easily perform analysis with appropriate analysis accuracy and sensitivity according to the type and state of the sample, the analysis purpose, and the like. An object of the present invention is to provide an emission analysis apparatus capable of performing the above.

An emission spectroscopic analyzer according to the present invention, which has been made to solve the above problems,
In an emission spectroscopic analyzer that detects and emits light having a specific wavelength by exciting a solid sample by discharge and wavelength-dispersing the emitted light with a spectrometer, the emitted light incident on the surface to be analyzed of the solid sample and the spectrometer It is characterized by comprising a lighting angle changing means for changing an angle θ formed by the optical axis.

The emission spectroscopic analyzer according to the present invention is as follows.
a) sample holding means for holding the solid sample;
b) a light guide optical system provided between the sample holding means and the spectroscope, for introducing a part of the emitted light into the spectroscope;
And the light angle changing means drives at least one of the optical elements included in the light guide optical system, whereby the light of the emitted light incident on the surface to be analyzed of the solid sample and the spectrometer It is desirable to change the angle θ formed with the axis.

  As the optical element, for example, a lens, a mirror, a light shielding mask, or the like can be used.

  According to the above configuration, by moving the optical element by the lighting angle changing means, the light emitted in any direction among the emitted light emitted in various directions by the excitation light emission of the sample is spectrally separated. It can change suitably whether it introduce | transduces into a container. Thereby, the same effect as changing the inclination angle of the sample mounting plate can be achieved. That is, if the optical element is driven so that light emitted at an angle close to parallel to the surface to be analyzed of the sample is guided to the spectrometer (that is, the angle θ is reduced), the above-described sample mounting plate High sensitivity analysis can be performed as in the case where the tilt angle is reduced (FIG. 6A). On the contrary, if the light emitted in the direction close to perpendicular to the sample surface to be analyzed is guided to the spectrometer (that is, the angle θ is increased), the inclination angle of the sample mounting plate is increased. Similar to (FIG. 6B), high-precision analysis can be performed.

Moreover, the emission spectroscopic analyzer according to the present invention further includes:
c) storing a plurality of analysis methods describing the analysis conditions of the sample, and storing means for storing information on the angle θ applied in the analysis by each analysis method;
d) Method designating means for allowing the operator to designate what is used for analysis from the analysis methods stored in the storage means;
e) When the analysis method is designated by the method designating means, information relating to the angle θ applied in the analysis by the analysis method is read from the storage means, and the control means for controlling the lighting angle changing means accordingly When,
It is desirable to have.

  According to such a configuration, just by the operator selecting an analysis method to be used for analyzing the sample, the angle θ suitable for the analysis by the analysis method is automatically specified, and the optical element and the like are automatically specified accordingly. Is positioned. Therefore, it is not necessary for the operator to be aware of the angle θ applied to the analysis of the sample, and the operator's operational burden related to setting the analysis conditions can be suppressed.

  Note that the “information about the angle θ” is not necessarily the value of the angle θ itself as long as it is information used to realize the angle θ, and control information necessary to achieve the angle θ. For example, it may be stored in the form of position information of the optical element. Further, the information on the angle θ may be included in each analysis method, and the information on the lighting angle corresponding to each method may be stored as a file separate from the analysis method.

  As described above, according to the emission spectroscopic analysis apparatus of the present invention, the angle θ formed by the analysis surface of the solid sample and the optical axis of the emitted light incident on the spectroscope is changed by the lighting angle changing means. This allows the accuracy and sensitivity of the analysis to be adjusted. Therefore, according to the emission spectroscopic analysis apparatus according to the present invention, it is possible to easily perform analysis with appropriate analysis accuracy and analysis sensitivity according to the type and state of the sample, the analysis purpose, and the like.

1 is a schematic configuration diagram of an emission spectroscopic analyzer according to an embodiment of the present invention. The side view which shows the structure of the light emission stand in the Example. The conceptual diagram which shows the change method of the lighting angle in the emission-spectral-analysis apparatus of the Example. It is a conceptual diagram which shows another example of the change method of the lighting angle in this invention, Comprising: (a) has shown the state which made the lighting angle small, (b) has shown the state which made the lighting angle large. It is a conceptual diagram which shows another example of the change method of the lighting angle in this invention, Comprising: (a) has shown the state which made the lighting angle small, (b) has shown the state which made the lighting angle large. It is a schematic diagram explaining the relationship between the inclination angle of the sample mounting plate, the analysis sensitivity, and the analysis accuracy in the conventional emission spectroscopic analyzer, where (a) shows high-sensitivity analysis and (b) shows high-precision analysis. Yes.

  Hereinafter, an embodiment of an emission analyzer according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an emission analyzer according to the present embodiment.

  This emission analyzer includes an excitation unit 10 that excites and emits a solid sample, a spectroscopic unit 20 that detects the light emitted from the sample by wavelength dispersion, and a control / processing unit 30 that controls each unit and performs data processing. Composed.

  The excitation unit 10 includes a sample stand, an electrode rod 12, a discharge generation unit 11, and a condenser lens 14. FIG. 2 is a side view showing a configuration of a main part of a sample stand (corresponding to a sample holding means in the present invention) 60 in the emission spectroscopic analyzer. A light emitting chamber 62 having an analysis opening vacated obliquely upward and a light guide space 63 for taking out light from the light emitting chamber 62 are provided inside the stand main body 61. An electrode rod 12 is provided. A sample placement plate 13 having a central opening 13a slightly smaller than the sample S is detachably attached to the surface of the stand main body 61 on which the sample S is placed, so that the sample S covers the central opening 13a. When placed on the sample placement plate 13, the lower surface (analyzed surface) of the sample S closes the analysis opening of the light emitting chamber 62. A support column 64 is erected on the stand main body 61, and the sample S placed on the sample placement plate is placed on the sample placement plate 13 by a pressing member 65 that can move along the support column 64. Pressed.

  The discharge generator 11 applies a pulsed high voltage to the electrode rod 12 in synchronization with a predetermined frequency (for example, 400 Hz). A sample S such as iron or non-ferrous metal is held on the sample stand 60 and is excited to emit light in an argon gas atmosphere by a spark discharge from the electrode rod 12. The emitted light passes through the light guide space 63 of the sample stand 60, is condensed by the condenser lens 14, and is introduced into the spectroscopic unit 20.

  Further, in the emission spectroscopic analysis apparatus according to the present embodiment, a light shielding mask 15 for blocking a part of the emitted light from the sample S is provided in front of the condenser lens 14 (side closer to the sample S). The light shielding mask 15 is movable in the radial direction of the condensing lens 14, and the light shielding mask is driven by a mask driving unit 16 including a motor or the like. In addition, the condensing lens 14 and the light shielding mask 15 correspond to the light guide optical system in the present invention, and the mask drive unit 16 corresponds to the lighting angle changing unit in the present invention.

  The spectroscopic unit 20 includes an entrance slit 21, a diffraction grating 22, exit slits 23a, 23b, and 23c arranged in parallel on the Roland circle, and detectors 24a, 24b, and 24c that are photomultiplier tubes. The spectroscopic unit 20 is a so-called Paschen-Lunge spectroscope. The exit slits 23a, 23b, and 23c and the detectors 24a, 24b, and 24c are arranged so as to detect spectral lines each having a wavelength specific to a specific element out of each wavelength light dispersed by the diffraction grating 22. Has been. For example, each of the detectors 24a, 24b, and 24c is disposed at a position for detecting spectral lines of carbon (C), silicon (Si), and manganese (Mn). Of course, it can be configured to detect not only these three elements but also a number of other spectral lines.

  The detection signals from the detectors 24a, 24b, and 24c are input to the control / processing unit 30, and predetermined data processing is performed to determine the intensity of the spectral lines of a certain element having a certain content. Based on this, a quantitative analysis for each element is performed.

  The control / processing unit 30 includes a data processing unit 31 for performing the predetermined data processing, a storage unit 32 for storing various settings, and a control unit 33 for controlling the operation of each unit as functional blocks. . For example, the control / processing unit 30 can be configured around a personal computer equipped with dedicated control / processing software, and is connected to an input unit 40 such as a keyboard and a mouse and a display unit 50 such as a monitor. .

  The storage unit 32 stores an analysis method file describing analysis conditions in the excitation unit 10, the spectroscopic unit 20, and the data processing unit 31. This analysis method file includes, for example, information such as discharge conditions (current amount and discharge time) in the excitation unit 10. Further, in this embodiment, in addition to information such as discharge conditions conventionally described in such an analysis method file, information on the light collection angle of emitted light by excitation light emission of the sample is described. Here, the daylighting angle corresponds to the angle θ in the present invention, and includes the optical axis of the emitted light incident on the spectroscopic unit 20 (that is, the daylighting axis of the spectroscopic unit) and the analysis surface of the solid sample. It means the angle formed by the optical axis and the surface to be analyzed in a vertical plane. As the lighting angle described in each analysis method file, an optimum one in the analysis under the other analysis conditions described in the analysis method file is experimentally or theoretically derived in advance. Such an analysis method file is created in advance by an operator or a manufacturer, and a plurality of types of analysis method files are registered in the storage unit 32.

  When analyzing a sample using the emission spectroscopic analysis apparatus according to the present embodiment, first, the operator operates the input unit 40 to analyze from a plurality of types of analysis method files stored in the storage unit 32. Select an appropriate analysis method file according to the element and sample concentration. When an analysis method file is selected, the method file is read from the storage unit 32 and transferred to the control unit 33.

  Thereafter, the operator places the sample S on the sample placing plate 13 of the sample stand 60 and instructs the start of analysis from the input unit 40. Upon receiving the instruction, the control unit 33 first controls the mask driving unit 16 based on the analysis method file. Thereby, the light shielding mask 15 is driven as shown in FIG. 3, and the light shielding mask 15 is positioned at a position where the lighting angle θ described in the analysis method file is obtained. Among the emitted light that is emitted from the analysis surface of the sample S at various angles and is directed to the condenser lens 14, some of the emitted light is blocked by the light shielding mask 15. Therefore, by moving the light shielding mask 15, The lighting angle θ can be changed. For example, when the lighting angle θ is reduced, the light shielding mask 15 is positioned at the position indicated by the solid line in FIG. 3, and when the lighting angle θ is increased, the light shielding mask 15 is indicated at the position indicated by the dotted line in FIG. 3. Positioning. In the former case, analysis can be performed with priority on sensitivity, and in the latter case, analysis can be performed with priority on accuracy.

  When positioning of the light shielding mask 15 is completed, the controller 33 controls the discharge generator 11 according to the discharge conditions described in the method file, so that spark discharge is performed from the electrode rod 12 to the surface to be analyzed of the sample S. Part of the emitted light generated by the evaporation excitation of the sample S by this discharge enters the condenser lens 14, passes through the entrance slit 21, and is introduced into the spectroscopic unit 20. The light introduced into the spectroscopic unit 20 is wavelength-dispersed by the diffraction grating 22, and predetermined spectral lines are detected by the detectors 24a, 24b, and 24c. Further, the detection signals from the detectors 24a, 24b, and 24c are processed by data processing. The result is analyzed by the unit 31 and the result is displayed on the display unit 50.

  As described above, according to the emission spectroscopic analysis apparatus according to the present embodiment, the lighting angle θ can be appropriately changed by changing the position of the light shielding mask 15, so that it can be used for the type and state of the sample, the analysis purpose, and the like. Analysis can be performed with optimum accuracy and sensitivity. In addition, since the daylighting angle θ is automatically set by designating the analysis method file, it is possible to perform analysis with appropriate sensitivity and accuracy without increasing the operation burden on the operator.

  In the above embodiment, the light guide optical system including the condensing lens and the light shielding mask is provided, and the lighting angle θ is changed by moving the light shielding mask. Alternatively, the light guide optical system may be constituted by a mirror or a mirror, and a part or all of the light guide optical system may be driven to change the daylighting angle θ.

Another configuration example of the light guide optical system in the present invention is shown in FIG. In this example, the light guide optical system includes a first fixed mirror 17 and a second fixed mirror 18 provided at a position where the light emitted from the sample S can be received, and a rotation provided on the light collection axis of the spectroscopic unit 20. And a mirror 19. The angles of the first fixed mirror 17 and the second fixed mirror 18 are unchanged. The rotating mirror 19 is rotatable about an axis A in the plane of the paper passing through the intersection of the surface of the spectroscopic unit 20 and the daylighting axis of the spectroscopic unit 20, and is rotated by a mirror driving unit (not shown) including a motor or the like. Is done. The emitted light emitted from the surface to be analyzed of the sample S at a predetermined angle θ ₁ enters the first fixed mirror 17, is reflected by the surface thereof, and travels toward the rotating mirror 19. On the other hand, light emitted from the surface to be analyzed at a predetermined angle θ ₂ larger than the angle θ ₁ enters the second fixed mirror 18, is reflected by the surface thereof, and travels toward the rotating mirror 19. Here, when the rotating mirror 19 is rotated as shown in FIG. 4A, the reflected light from the first fixed mirror 17 is reflected by the rotating mirror 19 and sent to the spectrometer 20. On the other hand, when the rotating mirror 19 is rotated as shown in FIG. 4B, the reflected light from the second fixed mirror 18 is reflected by the rotating mirror 19 and sent to the spectrometer 20. That is, according to this configuration, the lighting angle can be selectively switched to either θ ₁ or θ ₂ by changing the direction of the rotating mirror 19.

  Moreover, it is good also as a structure which changes the lighting angle (theta) by moving the sample mounting board 13 instead of the above optical elements. An example of such a configuration is shown in FIG. In this example, the main body of the sample stand 60 that holds the sample mounting plate 13 is fixed to a casing (not shown) of the excitation unit 10, and a movable unit that is rotatable with respect to the fixing unit 61a. It is comprised with the part 61b. By rotating the movable portion 61b, the angle formed by the optical axis of the light incident on the spectroscopic portion 20 and the surface to be analyzed of the sample S, that is, the lighting angle θ can be appropriately changed.

  As mentioned above, although the form for implementing this invention using an Example was demonstrated, this invention is not limited to the said Example, A change is accept | permitted suitably in the range of the meaning of this invention. . For example, in the above embodiment, the daylighting angle is automatically set by selecting the analysis method. However, in addition to this, the operator applies to the analysis in consideration of the type and state of the sample or the purpose of the analysis. The daylighting angle to be determined may be determined and input from the input unit.

  In the present invention, the excitation method of the sample for emission spectroscopic analysis is not particularly limited, and may be glow discharge, arc discharge, laser excitation, etc. in addition to spark discharge.

DESCRIPTION OF SYMBOLS 10 ... Excitation part 11 ... Discharge generation part 12, 74 ... Electrode rod 13, 72 ... Sample mounting plate 14 ... Condensing lens 15 ... Light shielding mask 16 ... Mask drive part 20 ... Spectroscopic part 21 ... Entrance slit 22 ... Diffraction grating 23a 23b, 23c ... exit slits 24a, 24b, 24c ... detector 30 ... control / processing unit 31 ... data processing unit 32 ... storage unit 33 ... control unit 40 ... input unit 50 ... display unit 60 ... sample stand 71 ... lighting axis

Claims (3)

  In an emission spectroscopic analyzer that detects and emits light having a specific wavelength by exciting a solid sample by discharge and wavelength-dispersing the emitted light with a spectrometer, the emitted light incident on the surface to be analyzed of the solid sample and the spectrometer An emission spectroscopic analysis apparatus comprising a lighting angle changing means for changing an angle θ formed by the optical axis of the light. a) sample holding means for holding the solid sample;
b) a light guide optical system provided between the sample holding means and the spectroscope, for introducing a part of the emitted light into the spectroscope;
And the light angle changing means drives at least one of the optical elements included in the light guide optical system, whereby the light of the emitted light incident on the surface to be analyzed of the solid sample and the spectrometer 2. The emission spectroscopic analyzer according to claim 1, wherein an angle [theta] formed with the axis is changed. Furthermore,
c) storing a plurality of analysis methods describing the analysis conditions of the sample, and storing means for storing information on the angle θ applied in the analysis by each analysis method;
d) Method designating means for allowing the operator to designate what is used for analysis from the analysis methods stored in the storage means;
e) When the analysis method is designated by the method designating means, information relating to the angle θ applied in the analysis by the analysis method is read from the storage means, and the control means for controlling the lighting angle changing means accordingly When,
The emission spectroscopic analysis apparatus according to claim 1 or 2, characterized by comprising:

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