JPS6113959Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an optical emission spectrometer that reduces noise in optical emission spectrometry using a plasma flame as a light source.

One of the methods of emission spectroscopy is a method that uses high-frequency inductively coupled plasma as a light source. In this case, argon is often used as an element constituting the plasma.
In high-frequency inductively coupled plasma using argon, the temperature of the argon gas is 10,000, and the electron temperature is higher than that. In such a state, there are excited argon atoms, ionized argon atoms, and further ion excited states in the plasma region, and the argon atoms and ions emit light. In optical emission analysis, a sample is introduced into such plasma, and the atoms of the sample components are excited by heat or electron bombardment to emit spectral lines unique to the atoms, which are then detected through a spectrometer. Detect and quantify elements using At this time, as mentioned above, the elements that make up the plasma (argon in the above example)
Atoms and ions also emit light, but this is completely unnecessary light and is a type of noise in measurements. The present invention was made with the aim of reducing the above-mentioned noise in emission spectroscopic analysis using a plasma flame as a light source.

The device of the present invention is characterized by utilizing atomic absorption to absorb and remove light emitted by the plasma itself, which serves as a sample heating source.

An atom has an energy difference E between its energy levels
absorbs a photon with energy equal to , becoming excited. That is, atoms absorb light of frequency ν (resonance absorption) with the relationship E=hν. A resonance line having particularly strong energy in the optical spectrum emitted from argon in the argon gas plasma is resonantly absorbed by the argon gas atoms placed in the optical path of the analyzer.

The present invention will be explained below with reference to Examples. Reference numeral 1 denotes a plasma torch, which is provided with a high-frequency coil 2 around its outer periphery, and is supplied with argon gas to form a plasma flame 3. The sample is atomized and introduced into the plasma torch 1 using a carrier gas, and heated and excited in a plasma flame to emit spectral lines unique to the atoms of the sample components. The light emitted from the plasma flame 3 is focused by a condenser lens 5 onto an entrance slit S of a spectrometer 4. Inside the spectrometer 4, a concave diffraction grating G and light receiving elements P1 to Pn are arranged at positions where diffraction images of spectral lines of the element to be analyzed are formed. The spectrometer 4 has a sealed structure and is filled with argon gas. Therefore, among the light incident from the entrance slit S, the spectral lines emitted from the argon atoms forming the plasma flame are transmitted from S→G→
While traveling along the optical path P1 to Pn, it is absorbed by the argon gas inside the spectrometer. Therefore, the light receiving elements P1 to Pn
The background noise due to resonance lines of argon atoms at the output of is significantly reduced.

In the above embodiment, the spectrometer itself is used as an absorption tank that absorbs the resonance spectrum emitted by the elemental gas that forms the plasma of the light source, but the optical path from the light source plasma to the spectrometer is filled with the same element as the plasma forming element. A tank may also be installed. Since the absorption rate is proportional to the concentration of the element, the required length of the tank can be reduced by increasing the filling gas pressure.

The device of the present invention has the above-mentioned configuration, and a tank filled with the same element that forms the plasma flame (argon in the above example) is placed in the optical path between the plasma flame of the light source and the light receiving element of the spectrometer. In the noise spectrum emitted from a plasma flame, emission spectroscopy using a plasma flame is achieved by effectively absorbing resonance lines emitted by the plasma flame forming elements themselves, which have a particularly high intensity and have a large interference effect on measurements. The sensitivity of analysis can be increased.

[Brief explanation of the drawing]

The drawing is a plan view of an apparatus according to an embodiment of the present invention. 1... Plasma torch, 4... Spectrometer, G...
Concave diffraction grating, P1 to Pn...photodetector.

Claims (1)

[Scope of utility model registration request] Plasma light emission spectroscopy consists of a plasma formation device for a light source and a closed-type spectrometer, and the spectrometer is filled with the same elements as those for plasma formation, excluding the sample, and doubles as an absorption tank to absorb the light emitted by the plasma. Analysis equipment.