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TECHNOLOGY FOR ANALYZING METAL BY OPTICAL EMISSION SPECTROMETER

Optical Emission Spectrometry-OES is one of the most widely used spectral analysis techniques in analyzing chemical elements of metal samples such as steel, cast iron, aluminum, copper, lead, zinc, titanium ... for quick and accurate analysis results.

Most of the Optical Emission Spectrometers are based on the same principle of operation but different manufacturing technologies. The difference is mainly in the Detector. Currently, the following three types of detectors are used in the world to produce spectrometer:

  • CCD - Charge – coupled device
  • PMT - Photomultiplier tube
  • CPM - Channel Photomultiplier

They are widely used and known both as CCD and PMT. The following table compares the technology characteristics, advantages and disadvantages of each method.

 

CCD

PMT

Operating principles

The resulting light is white light (the sum of many monochromatic light) and the spectrum analyzer determines the wavelength and magnitude of the spectral lines from which the elements and their concentrations are determined in the alloy.

Photomultipliers are typically constructed with an evacuated glass housing (using an extremely tight and durable glass-to-metal seal like other vacuum tubes), containing a photocathode, several dynodes, and an anode. Incident photons strike the photocathode material, which is usually a thin vapor-deposited conducting layer on the inside of the entry window of the device. Electrons are ejected from the surface as a consequence of the photoelectric effect. These electrons are directed by the focusing electrode toward the electron multiplier, where electrons are multiplied by the process of secondary emission.

Sensitivity

Medium

High

Spectrum range

Detecting most of the wavelengths of light with a wavelength range of 145-675nm, some elements with VUV such as Oxygen, Nitrogen, and Hydrogen will not be detected.

Wide, from ultraviolet wavelength to infrared wavelength.

Accuracy

Medium, depends on factors such as Argon gas, temperature, power stability, sample surface ...

High

Stability

Medium, depends on factors such as Argon gas, temperature, power stability, sample surface ...

High

Upgrade analysis

There are 2 type of spectrometer 13 CCD with 1 spectroscopy chamber to covers wavelength range 200-675nm(this model cannot upgrade during operation). And 16 CCD with 2 spectroscopy chambers to cover wavelength range 145-675nm.

Each PMT receives a monochromatic wavelength, need to add new PMT when do upgrading

Shimadzu’s Spectrometer

PDA-MF/MF Plus

http://tecotec.com.vn/may-quang-pho-phat-xa-oes-1/may-quang-pho-phat-xa-pdamf.html

 

PDA-5000

http://tecotec.com.vn/may-quang-pho-phat-xa-oes-1/may-quang-pho-phat-xa-pda5000.html

PDA-7000

http://tecotec.com.vn/may-quang-pho-phat-xa-oes-1/may-quang-pho-phat-xa-pda7000.html

PDA-8000

http://tecotec.com.vn/may-quang-pho-phat-xa-oes-1/may-quang-pho-phat-xa-pda8000.html

 

Source: ETA

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