How do Atomic Emission Spectrometers Work?

The basic principle on which atomic emission spectrometer work is the employment of high temperature of the arc, which vaporizes every single element in the sample. The spectral lines emitted cross the exit slit and arrive in the respective photomultiplier tubes. The optical signal is converted to an electoral signal, and ultimately percentage content of each element is determined.


The difference between a full-spectrum atomic emission spectrometer and an ordinary spectrometer:


Various spectrometers are available that offer multiple application ranges. Therefore, everything narrows to what a full spectrum atomic emission spectrometer offers that an ordinary spectrometer doesn’t?


The photomultiplier present in the instrument acts as a point measurement that reads discrete spectral lines. Each channel element corresponds to the photomultiplier; therefore, one tube must be present for one element. The spectral line appears as a mono wavelength which makes continuous receiving difficult. The analytical spectral line choices are also limited. If the number of elements is high, more PMTs are employed. Photomultiplier technology-based spectrometers cannot add analysis matrices. If they’re added, the number is limited, and the effect does not justify the cost.


The Charged Coupled Device is a surface scanning device that needs cryogenic treatment. Three CCDs can cover the majority of the elements. The spectral analysis lines are set as per the requirements. The basic concept is that a component with multiple characteristic spectral lines can help select the multiple analytical spectral lines. The addition of channels and increase in matrix types is suitable later. It is more flexible than the standard channel type (photomultiplier tube, PMT). If customers’ elemental analysis needs change in the future, they can add the appropriate analysis program without modifying the instrument hardware, making the upgrading very simple. The cost of a CCD is less than that of a photomultiplier tube, a late-stage technology. PMTs are recommended for ultra-high precision and ultra-low content analysis. The diameter of the pipe is often publicized by the manufacturers, but the analysis optical chamber size often makes one reconsider their decision.


The CCD allows the spectral lines of all elements in the designed band to be recorded. It’s an advantage as each element exhibits a different spectral line characteristic at various concentrations. The device collects and evaluates each element. If the PMT is employed, the content range of analytical elements is high, and the configuration of multiple PMTs becomes a necessity. The manufacturer of the instruments only offers the configuration of PMT of analysis range if the user asks for it.


Adjusting the production process in each factory requires an unconventional production skill compared to other manufacturers. Two things can be done:

  • Increase the elements.
  • Extent the functional analysis curve.

The CCD is better than the PMT-type atomic emission spectrometer for upgrade and transformation follow-up.


Advantages and disadvantages of atomic emission spectrometer CCD technology and PMT technology:


Advantages of atomic emission spectrometer CCD technology:

  • All spectra and element spectral lines are recorded, and multiple spectral lines of the same elements can also be determined.
  • It offers an unlimited channel setting. The upgrade is relatively easy, and multiple matrixes can be evaluated.
  • High integration and miniaturized volume are offered by the instrument.
  • It offers high stability, simple operation, and a relatively low failure rate.
  • Energy saving and consumption and material saving properties are half of the ordinary spectrometer.

Disadvantages of atomic emission spectrometer CCD technology:

  • The sensitivity of the instrument is disappointing, and detection is limited to 5ppm.
  • The temperature requirement of the instruments requires an air-conditioned environment.


Advantages of PMT traditional tube technology:

  • Channel element wavelength and fixed element channel cannot be selected.
  • Channel settings are constant or limited, and the upgrade is non convenient.
  • The instrument is heavy and difficult to move.
  • Most devices are made up of discrete components with low dependability and stability.


Disadvantages of PMT traditional tube technology:

  • The sensitivity is high, and content below 5ppm is detected, but all theoretical.
  • The temperature requirement of the instruments requires an air-conditioned environment.

Which one is better; Atomic emission spectrometer direct empty chamber or an argon-filled chamber? 


Theoretically, no difference exists between the two instruments; however the following differences have been observed:

  1. Vacuum Type Instrument: The instrument’s production cost is high mainly due to the vacuum design, leak rate guarantee, pump, value and oil return, and mist prevention.
  2. Argon gas type instrument: This one has a relatively low production cost due to the absence of vacuum design, leak rate guarantee, oil return, and mist prevention. Argon gas is simply blown into the instrument, but the argon needs to be refilled repeatedly, making it less cost-effective in the long term. The purity of the argon gas can affect the accuracy of the instrument.


Is CCD or CMOS better for a full-spectrum atomic emission spectrometer?

CMOS is a comparatively better option when compared to CCD. Multiple benefits and latest generation properties make it a suitable choice.


Full Spectrum Atomic Emission Spectrometer CCD: 

The CCD takes a unique approach to the vacuum light chamber design and all digital excitation light sources. The detector in the instrument uses a high-speed data exchange system primarily used in metallurgy, casting, machinery, automobile, shipbuilding, electric aviation, and other fields.


A high-performance optical system design and high-precision optical components can accurately determine the contents of non-metallic elements. It offers accurate results, excellent reproducibility, and long-term stability.


Full Spectrum Atomic Emission Spectrometer CMOS: 

Just like CCD, CMOS can also record the entire spectrum. The optical path of the CMOS receives wavelength spectrum lines from the deep UV region, which is broader than the spectrum range offered by the CCD spectrometer. Additionally, the COMS shows flexibility in expansion, and any defect of the CCD spectrometer that cannot reach the high-precision metal element analysis is defeated by the CMOS.


Despite the fact that both lie in the photoelectric conversion detector category, CMOS offers higher sensitivity than CCD. Therefore, the accuracy of the former is better than the latter. Not to forget that CMOS acts as a planar detector with full-spectrum characteristics.


To summarize, CMOS offers all of the advantages of CCD, but certain aspects make it superior. However, when selecting a spectrometer, it is best to consider your specific needs.



How to choose an excitation electrode for an atomic emission spectrometer?

Various excitation electrodes such as carbon, copper, aluminum, silver, tungsten, etc., are available for atomic emission spectrometer. However, the excitation electrode must be selected based on the analysis method and object. It’s believed that electrode selection is better when the precision of the technique is necessary. Moreover, the element to be tested should not be a part of the excitation electrode.


Silver as an excitation electrode is a good option as pure silver is easy to find and exhibits a high melting point. It also has reasonable thermal conductivity, good heat capacity, corrosion resistance, and electrical conductivity. The best part is that silver is not present in steel; therefore, the accuracy offered by a silver electrode is tremendous for steel analysis. When a uni-directional discharge excitation light source is employed, the erosion of the excitation electrode takes place. A tungsten lamp is often used, which does not require frequent cleaning but shows resistance in growing sharp.


How to avoid elemental interference when analyzing an aluminum base with an atomic emission spectrometer?

  1. Use of standardized samples with identical compositions for calibration.
  2. Spectral and chemical analysis to be performed on own samples for which the data is compared. Manual adjustment of the element interference is also made.

How do we distinguish the quality of the curve when analyzing the alloy by atomic emission spectrometer?

It depends entirely on the difference between the standard measurement and actual values. More minor deviations indicate successful curves.


When can the vacuum degree of the atomic emission spectrometer decrease and the negative high pressure not be added?

The addition of high pressure is restricted due to the lack of vacuum space. Ether can be used to check the gas path for a leak.


What effect does temperature have on atomic emission spectrometers?

Atomic emission spectrometer offer high precision for results. Therefore, any slight change in the optical system can result in significant measurement errors. To avoid this, the spectrometer is designed to control the temperature of the optical system constantly. However, variations in external temperature still influence the thermal equilibrium state of the constant temperature system. Precision can be achieved if the ambient temperature does not even 5°C.

Manufacturers have temperature restrictions for the instrument between 10–30°C. The instrument’s temperature is approximately 20°C during factory calibration so that higher accuracy can be achieved within the temperature restrictions set by the producers. The ambient temperature used by the instrument must be consistent with the constant temperature of the spectrometer for the constant temperature control of the spectrometer to function correctly. The ambient temperature must be below 30C and the atomic emission spectrometer must regulate the ambient temperature while the instrument is in use. Additionally, an air-condition environment must be provided.