Gas Cell Pretreatment for Accurate Raman Impurity Analysis

The patent applies preliminary action by performing a pretreatment step before the actual analysis. This involves introducing a dry gas (such as nitrogen or sulfur hexafluoride) into the gas cell to reduce the water vapor partial pressure to 10 Pa or less before introducing the sample gas for Raman spectroscopy analysis. This preliminary removal of water prevents subsequent reactions between water and reactive impurities, thereby maintaining high analysis accuracy.

The patent applies parameter changes by establishing a specific threshold for water vapor partial pressure (10 Pa or less) that must be achieved during the pretreatment step. By defining this quantitative parameter, the pretreatment process becomes controllable and optimizable. The dry gas flow rate, treatment duration, and temperature can be adjusted to achieve this threshold efficiently, balancing the need for high analysis accuracy with reasonable process time.

The patent applies the inert atmosphere principle by using dry gas (such as nitrogen or sulfur hexafluoride) to create a water-free environment in the gas cell during pretreatment and analysis. This inert, dry atmosphere prevents corrosion of the gas cell and other equipment components by reactive impurities, thereby maintaining equipment integrity and reliability. The dry gas acts as a protective medium that eliminates the harmful effects of water vapor.