JPH0641914B2 - Emission spectroscopy analyzer using selective excitation - Google Patents

Description

TECHNICAL FIELD The present invention relates to an emission spectrophotometer for performing quantitative and qualitative analysis from an emission spectrum.

[Background of the Invention]

At present, emission spectroscopy is popular as a highly sensitive elemental analysis method. In this emission spectroscopic analyzer, the arc method, spark method, plasma jet method,
There is an ICP (inductively coupled plasma) method or the like. There are many emission lines in emission spectroscopy, their density is high, the lines are forested, and the element of the target analysis line (usually 1 or 2) overlaps with the line of other elements and cannot be identified. There are cases. Therefore, it is necessary to increase the resolution in order to separate the overlapping elemental analysis lines. Therefore, regardless of which analysis method is used, a large-scale spectroscope is used for the spectral analysis. Large spectroscopes are used
This is because, as described above, the emission spectrum generally consists of an extremely large number of emission images, and high resolution is required to separate the analysis line of the target element. For example, when iron or steel is analyzed, the emission spectrum line reaches several thousand in the ultraviolet / visible wavelength range only. Therefore, usually a spectroscope having a resolution of 5Å / mm is used. Due to the limitation of the large-sized spectroscope, the emission analysis device has conventionally been large-sized and expensive.
In addition, recently, the demand for analyzing rare earth elements is increasing in the fields of new materials, nuclear power, etc., but rare earth emits a large number of emission lines, and a spectrometer with high resolution is required. It is coming.

Japanese Unexamined Patent Publication No. 57-133340 discloses a measuring method in which excitation light having an energy larger than a certain level is applied to a sample and photoluminescence generated at that time is detected. However, it does not disclose anything about limiting the upper limit of the particle energy level of the particle beam incident on the sample. In addition, JP-A-50
No. 126490 discloses a monochromator that emits a beam having a selective excitation wavelength, but does not disclose how to control the energy level of particles incident on a sample.

[Object of the Invention]

An object of the present invention is to provide an emission spectrophotometer that is compact and can obtain a desired analytical line.

[Outline of Invention]

The present invention is intended to obtain a simple analytical spectrum by selectively exciting only a specific level of an atom to obtain a desired analysis line.

Example of Invention

 Examples of the present invention will be described below.

FIG. 1 shows an embodiment of the present invention.

In the figure, an ion source 2 is provided on one side of a chamber 1. The ion source 2 is connected to the anode 3.
Deflection electrodes 4 and 5 are provided on the ion emission side of the ion source 2. The ion source 2 is configured so that an electron beam 7 output from an electron source (filament) 6 is accelerated and supplied. The electrons supplied from the electron source 6 cause the ion source 2 to form ions. Then, the ions are accelerated, deflected by the deflection electrode, and emitted. An energy selection iris 9 provided on an insulating plate 10 is provided in the path of the ion beam 8 emitted from the ion source 2. The ion beam 8 passing through the energy selection iris 9 strikes a sample (target) 12 supported by a sample holder 11, and output light 13 from the sample 12 is a light window (quartz plate) provided in the chamber 1. ) Is output. A flange 15 is attached to the side of the chamber 1 facing the ion source 2, and a sample holder 10 is provided on the flange 15. Further, an exhaust port 16 is provided in a part of the chamber 1 on the side of the ion source 2, and air is exhausted from the exhaust port 16 by a vacuum pump (not shown) so that the inside of the chamber 1 becomes a vacuum. There is.

With this configuration, the sample to be analyzed (for example, steel) is mounted on the sample holder 11 fixed to the flange 15. After the airtightness is maintained by the flange 15, the inside of the chamber 1 is evacuated by a vacuum pump (not shown) to maintain a vacuum of 10 ⁻⁴ to 10 ₋₆ Torr. Then, an acceleration voltage of several KV is applied between the electron source 6 and the ion source 2. Now, from the electron source 6 to the electron beam 7
Are acceleratedly supplied, and the supplied electrons collide with the ion source 2 at high speed to form ions by the spattering phenomenon. The ions generated in this way have a (+) charge and thus are accelerated toward an electron source having a (-) potential. Ions in the ion source 2 are deflected by the deflection electrodes 4 and 5. Ions having a lower internal energy of the ion beam 8 are deflected more, so that dispersion occurs in the flight direction of the ions. Therefore, by providing the energy selection iris 9, only ions having a specific energy can be selected. The ions that have passed through the energy selective iris 9 collide with the sample 12 on the sample holder. If the collision velocity of ions at this time is v, the following (1)
The energy of the equation causes the sample to be sputtered and excited.

However: m is the mass of the ion.
It is taken out from the outside and observed. Further, in reality, the energy E has a width due to the hole diameter of the energy selection iris 9. As the ion source, it is also possible to heat a low boiling point metal such as C _s to obtain atomic vapor without using the spattering phenomenon due to accelerated electrons and generate ions by electron collision.

The selective excitation in this embodiment will be described next. For example, N _a
Some of the energy levels of are as shown in FIG. The N _a is the Boltzmann distribution at room temperature, most of the atoms is a ground state Have. When energy is given from the outside and excited to an upper level, a transition occurs between the quantum mechanically allowed levels, and light having a wavelength having the following relation with respect to the energy difference ΔE is emitted.

ΔE = hν (2) where ν is the frequency of emitted light and h is Planck's constant.

Selective excitation in this embodiment, the selective excitation between E ₂ to E _3, to excite atomic level between E ₂ to E _3, the light in the process of transition from the excited state to the level of the low energy To observe the release of. The advantage of this method is that E ₂
~ By narrowly selecting E ₃ , Can be excited, and in the simplest case, a spectrum consisting of only two (or one) emission lines can be obtained. In this case, the spectroscope is unnecessary. That is, by changing the energy of selective irradiation (corresponding to the central energy of E _{2 to} E ₃ ), it is possible to obtain a light emission line specific to the element. The narrower the energy gap between E _{2 and} E _3, the better the selectivity.

FIG. 3 shows another embodiment of the present invention.

In the figure, a flange 101 is attached to the chamber 100. The sample holder 1 is attached to the flange 101.
02 is attached, and a sample 103 for forming a cathode is provided on the sample holder 102. An anode 104 is provided to face this sample. This anode 104
A magnetic field H is formed near the cathode 103 in the direction of the drawing. An air exhaust port 105 is provided on one side of the chamber 100, and a gas inlet 106 is provided on the other side. In addition, a light window (quartz plate) 107 is provided on the chamber 100.
Is provided, and the output light 1 output from the sample 103
08 can be taken out.

The anode 104 is connected with a yoke coil 109 and a capacitor 110. This chain coil 109
A chain yoke coil 113 is connected to the capacitor via a parallel circuit of a capacitor 111 and a DC power source 112. The other end of this yoke coil 113 is grounded together with the shadow 103. The high frequency power supply 11
4 is connected, and the high frequency power supply 114 is grounded via a capacitor 115.

In the case of this example configured as described above, the sample (metal) is mounted on the sample holder 102 fixed to the flange 101. The chamber 100 evacuates air from the air exhaust port 105, and once evacuates it to a vacuum, introduces a rare gas such as argon or neon from the gas inlet 10. The pressure of this gas is 1 to 10 Torr, and a high degree of vacuum is not required unlike the embodiment shown in FIG. Further, a (−) potential is applied to the sample 103 to cause discharge between the sample 103 and the anode 104. In a normal DC discharge, an experiment with the device according to this example showed that a discharge sustaining voltage of at least 180 V was required. However, a decrease in discharge sustaining voltage of about 60 V was observed by applying a magnetic field, and a decrease in discharge sustaining voltage of about 145 V was observed by applying a high frequency.

The selective excitation in this embodiment is a method of exciting atoms by determining the upper limit E ₁ of energy. N shown in FIG.
_At room temperature, most of the atoms are at the lowest level ground level. It is in. Now, when excited with an energy corresponding to E ₁ , only the level closest to the ground level is excited, and only the light emission transiting to the ground state is observed. The transition to the ground level is generally called a resonance transition, and the spectral line is called a resonance line. In the conventional emission analysis method, it has been customary to excite near the ionization level, so that an extremely large number of spectral lines have been observed. The change of the discharge sustaining voltage depending on the strength of the applied magnetic field is shown in FIG. 4 together with the presence or absence of high frequency application. In the figure, A is a curve of DC discharge, and B is a curve of flow plus high frequency discharge. The high frequency used here is 100 MHz and 10 W. From FIG. 4, when a high frequency and a magnetic field are applied to perform discharge, the discharge sustaining voltage is suppressed to about 35V. It has been found that, when such a special discharge is performed, only the level having much lower energy is selectively excited as compared with the level excited by the normal discharge.

As shown in FIG. 5, in a general discharge, an extremely large number of spectral lines are observed in the UV-visible wavelength region, but when excited by a DC discharge in which the above high frequency and magnetic field are superposed, a resonance line (from the ground level) It was found that only the (transition of) emits intense light. FIG. 6 shows an example of the emission spectrum when the sample is cd. Thus, if only the resonance line of each element mainly emits light, the spectrum is relatively simple and a large-scale spectroscope with high resolution is not required even when many metals are mixed. The dispersive power is about 25 Å / mm, and the size of the spectroscope is about 1/5.

In this embodiment, only a vacuum pump or a rotary pump is required, the light emission source is small and simple, and a compact and low-cost emission spectrophotometer can be realized as the entire system.

〔The invention's effect〕

As described above, according to the present invention, the upper limit of the energy level of particles incident on the sample is limited to a low value,
It is possible to control the excitation energy by limiting the upper and lower limits, and it is possible to keep the number of atomic spectra emitted from the sample at a low value, so use an emission spectrophotometer with low resolution. You can

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an emission spectroscopic analyzer of the present invention, FIG. 2 is a diagram showing the energy level of atoms by taking N _a as an example, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a diagram showing the relationship between magnetic flux density and discharge sustaining voltage, FIG. 5 is a diagram showing an emission spectrum by a conventional emission analyzer, and FIG. 6 is a diagram showing an emission spectrum according to the present invention. 2 ... Ion source, 4,5 ... Deflection electrode, 6 ... Electron source,
12 ... Sample, 14 ... Light window.

Claims (3)

[Claims] 1. A particle accelerated into an energy range having a specific energy width is made to collide with a sample, and only energy levels falling within the specific energy range are selectively excited. In an emission spectrophotometer configured to perform quantitative or qualitative analysis by observing luminescence, it comprises means for selecting particles accelerated in an energy range having a specific energy width, and the means for selecting comprises
A portion other than the opening is provided with a deflection electrode that is arranged in the path of the accelerated particle beam and deflects the particle beam, and an opening that is arranged in the path of the particle beam that connects the deflection electrode and the sample and that allows the particles to pass therethrough. An emission spectrophotometer comprising: a selection unit that rejects passage of particles. 2. A particle accelerated into an energy range having a specific energy width is made to collide with a sample, and only energy levels falling within the specific energy range are selectively excited. An emission spectroscopic analyzer adapted to perform quantitative or qualitative analysis by observing issuance includes means for accelerating particles in an energy range having a specific energy width, and the accelerating means accelerates particles. And an electrode for applying a magnetic field between the electrodes, and an emission spectrophotometer. 3. The emission spectroscopic analyzer according to claim 2, wherein the electrode for accelerating the particles is constructed so that the high frequency discharge can be superimposed on the direct current discharge.