Determination of ppb-Level CO, CO2, CH4, and H2O in High-Purity Gases Using Matrix Isolation FT-IR with an Integrating Sphere

Abstract

Parts per billion-level CO, CO 2 , CH 4 , and H 2 O are determined in high-purity argon and nitrogen gases by using matrix isolation Fourier transform infrared spectrometry with an integrating sphere. A linear response was observed in the corrected absorbance vs concentration of CH 4 and H 2 O in both malices. While a linear response was also observed for CO and CO 2 in argon matrix, a nonlinear response was found in nitrogen matrix. The latter is probably due to internal vibrationphonon interaction. Addition of argon into the nitrogen matrix resulted in a linear response. Comparison with gas-phase FT-IR shows that the combination of the matrix isolation FT-IR technique with an integrating sphere allows an enhanced sensitivity with a reduced sample volume