The reason why high purity argon must be used when using the spectrometer is mainly based on the following reasons:
First, improve the sensitivity of elemental analysis.
High-purity argon is used as an inert gas, which can stimulate Sparks (ARCs) when the machine is running and protect the excited sample from other impurity gases. This is conducive to the excitation of metals at high temperatures, so that the atomic energy level jumps, thereby improving the sensitivity of elemental analysis. Oxygen and moisture in the air will absorb the spectrum generated by the energy level transition, resulting in inaccurate measurement of non-metallic elements. The oxygen and moisture content in high-purity argon is extremely low, which can ensure the full excitation of the spectrum and make the data effective and accurate.
Second, isolate the air to prevent interference
argon is inert and does not react chemically with the material under test. At the same time, it can isolate the air by its inert specific gravity to prevent the oxygen and moisture in the air from interfering with the spectral analysis. In particular, oxygen and moisture in the air will oxidize the metal in the high-temperature molten state to form a protective film, prevent the further melting and evaporation of the sample, cause the “diffusion discharge” phenomenon (ie, “White spots”), and affect the analysis results. The high-purity argon can drive the air in the spark system to avoid this interference.
Third, stable plasma to improve performance
in the ICP spectrometer, high purity argon is used as the working gas, which can generate the ionized gas of the plasma. The resistivity, thermal melting and thermal conductivity of argon are low, which helps to reduce the energy loss caused by thermal conduction and heat dissipation and improve the thermal efficiency of the plasma. At the same time, argon is easier to form a stable ICP (inductively coupled plasma), and the required high-frequency power is also low. This is conducive to the spectrometer to play its better performance, accurate analysis.
Ensure data accuracy and reproducibility
the spectrometer needs a stable gas source in the analysis process to ensure the accuracy and reproducibility of the measured data. Especially when the determination of trace and ultra-low content elements, the quality of the gas source on the analysis results is particularly significant. High purity argon (purity requirement ≥ 99.999) can ensure the purity of the gas source, thus avoiding the analysis error caused by impure gas source.
To sum up, the reason why the spectrometer must use high-purity argon is that high-purity argon can improve the sensitivity of elemental analysis, isolate air to prevent interference, stabilize plasma to improve performance, and ensure data accuracy and reproducibility. These advantages make high purity argon become an indispensable element in spectrometer analysis.