JPH0213833A - Icp emission analyzer - Google Patents

Abstract

PURPOSE:To enable the obtaining of a spectrum data with high resolutions by a method wherein a plasma flame is irradiated with a laser light from a variable-wavelength laser to measure a change in ion current sweeping the wavelength of the laser light. CONSTITUTION:As an induction coil 10 is supplied with a high frequency current from a high frequency power source 12, a plasma torch 2 generates a plasma flame 14. A sample 4 is atomized with a nebulizer 6 to be introduced to the plasma flame 14, which causes the sample to be excited to emit light. A laser light undergoes a wavelength sweeping with a wavelength sweep control section 18 irradiating the plasma flame 14 excited with the laser light from a wavelength varying laser 16. Here, when a sample element absorbing the laser light with a corresponding wavelength exists, ion number in the plasma flame 14 varies to change an ion current flowing between electrodes 22. A change in the ion current is detected with a detector 28 to obtain a specified spectrum data thereby achieving qualitative and quantitative analysis on element in the sample.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an ICP (inductively coupled plasma) emission spectrometer.

(B) Prior Art In a conventional ICP emission spectrometer, high frequency power is supplied from a high frequency power supply to a plasma torch, and a sample to be analyzed is atomized by a nebulizer and introduced into the plasma torch. Then, the atomized sample is excited in a plasma torch to emit light, the light is separated into element-specific spectral lines using a spectroscope, and the presence and intensity of each spectral line is detected using a photodetector. Perform qualitative and quantitative analysis of each element contained in the sample.

(c) Problems to be Solved by the Invention As described above, the conventional devices of this type have 1. A spectrometer and a photodetector are essential to convert plasma light into information about each spectral line.

As a result, the equipment becomes larger and more expensive.
Ru. Furthermore, a spectrometer is a precision instrument, and when it is used, it must be kept in a constant environment to eliminate the effects of drift caused by temperature, vibration, etc., and maintenance is time-consuming.

The present invention has been made in view of these circumstances, and allows the acquisition of high-resolution spectral data without using a spectrometer or photodetector, thereby reducing the overall cost of the device compared to conventional methods. The purpose is to make the device compact and easy to maintain.

(d) Means for Solving the Problems In order to achieve the above object, the present invention adopts the following configuration.

That is, in the ICP emission spectrometer of the present invention, a wavelength tunable laser that irradiates a laser beam to a plasma flame generated by a plasma torch, a pair of electrodes that are disposed opposite to each other with the plasma flame in between, and both of the electrodes are provided. and a detector that detects the ionic current flowing between the two.

(E) Effect According to the above configuration, the plasma flame generated by the plasma torch is irradiated with laser light from the wavelength tunable laser. At this time, due to the photogalvano effect, if there are atoms that absorb the laser light, the number of ions changes and the ionic current flowing between the electrodes changes. This change in ion current is detected by a detector. Therefore, by measuring the change in ion current while sweeping the wavelength of the laser beam, the required spectral data can be obtained.

(f) Example FIG. 1 is a block diagram of an ICP emission spectrometer according to an example of the present invention. In the same figure, the symbol l indicates the entire CP emission spectrometer, 2 is a plasma torch, 4 is a sample, 6 is a nebulizer that atomizes the sample 4, and 8 is a gas that supplies gas such as Ar to the plasma torch 2. In the control device, IO is an induction coil for generating high-frequency plasma, 12 is a high-frequency power source that supplies high-frequency power to the induction coil IO, and 14 is a plasma flame generated by the plasma torch 2.

This embodiment includes a variable wavelength laser 16 that irradiates the plasma flame 14 with laser light. Various dye lasers can be used as the wavelength tunable laser 16, but
In particular, pulsed and laser-excited dye lasers (for example, N, laser-excited dye lasers) that can provide highly efficient oscillation in a wide wavelength range are applied. In addition, 18 is a wavelength tunable laser 16
This is a wavelength sweep control unit for sweeping the wavelength of . 20 is a half mirror placed on the optical path of the laser beam. 122 is a plasma flame! A pair of electrodes are placed opposite each other with 4 in between. Each of these electrodes 22 is constantly cooled by water cooling or the like, and a high voltage is applied between the picture electrodes 22 by a high voltage power source 24. 26 is a photoelectric conversion element (photodiode in this example) that detects the laser beam reflected by the nof mirror 20; 28 is a detector that detects the ion current flowing between the picture electrodes 22; It consists of a tuned amplifier 30 and a boxcar integrator 32. 34 is a data processing unit that obtains spectrum data based on the relationship between the ion current detected by the detector 28 and the sweep wavelength of the laser beam, and performs qualitative and quantitative analysis of elements in the sample.

Next, the operation of the ICP emission spectrometer 1 having the above configuration will be explained.

When a high frequency current is supplied from the high frequency power source 12 to the induction coil 10, a plasma flame 14 is generated in the plasma torch 2 due to its electromagnetic induction action. A sample 4 is atomized by a nebulizer 6 and introduced into the plasma flame 14 . This excites the sample and emits light. Further, a high voltage is applied between the picture electrodes 22 by the high voltage power supply 24 in advance.

Then, while the wavelength tunable laser 16 irradiates the plasma flame 14 in which the sample is excited with pulsed laser light, the wavelength of this pulsed laser light is swept by the wavelength sweep control section 18 . If a sample element suitable for absorbing the laser light of this wavelength exists, the number of ions in the plasma flame 14 changes due to the optical galvano effect, and accordingly, the number of ions in the picture electrode 22 changes.
The ionic current flowing between them changes. This change in ion current is amplified by a tuned amplifier 30 and then input to a boxcar integrator 32. On the other hand, a part of the laser light from the wavelength tunable laser 16 is detected by the photodiode 26 via the half mirror 20, and the detection output is inputted to the boxcar integrator 32 as a sampling trigger signal. Thereby, the ion current is sampled and sequentially integrated in synchronization with the timing of the laser beam pulse output.

Then, based on the integrated intensity value of the boxcar integrator 32 corresponding to the swept wavelength of the wavelength tunable laser 16, the data processing section 34 obtains required spectrum data as shown in FIG. Further, the data processing unit 34 performs qualitative and quantitative analysis of the elements in the sample by comparing the obtained spectra with the database of each element.

In this embodiment, a change in the number of ions in the plasma is detected as a change in the ion current flowing between the electrodes 22, but in addition, a change in the impedance of the plasma load can be detected as a change in the high frequency reflected wave for plasma generation. It is also possible to detect.

(g) Effects According to the present invention, since spectroscopic measurements are performed using the optical galvano effect, high-resolution spectral data can be obtained without using a spectrometer or a photodetector. As a result, the entire device can be made smaller in size compared to the conventional method, and excellent effects such as easier maintenance are exhibited.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a configuration diagram of an ICP emission spectrometer, and FIG. 2 is a characteristic diagram showing the relationship between the wavelength of laser light and the detected ion current. DESCRIPTION OF SYMBOLS 1... ICP emission spectrometer, 16... Tunable wavelength laser, 22... Electrode, 28... Detector.

Claims (1)

[Claims] (1) A variable wavelength laser that irradiates a plasma flame generated by a plasma torch with laser light, a pair of electrodes that are placed opposite to each other with the plasma flame in between, and detecting the ionic current that flows between the two electrodes. An ICP emission spectrometer comprising: a detector;