Extractive Fourier Transform Infrared Spectroscopy (FTIR) is a versatile and precise method for process gas analysis and emission monitoring. Its application is widespread and covers such diverse applications as emissions measurements from waste incineration and process gas analysis in the semiconductor industry. Given the specific absorption of nearly all gases in the infrared, FTIR can perform simultaneous measurement of both organic and inorganic compounds, as well as analyze hot, wet and corrosive gas streams. Simultaneous detection of multiple species is possible with high time resolution, and measurement capabilities typically range from ppb up to percent levels. Our group has many years of experience in extractive FTIR analysis, which can be illustrated by the two examples below.

A very frequent process is the chemical vapor deposition (CVD) of tungsten. Our studies in several semiconductor fabs indicate significant optimization potential with respect to gas consumption and process time. Furthermore, unexpected reaction by-products can be identified, which in some applications were shown to be a source for decreased yield.

In waste incineration plants, nitrogen oxides (NOx) are often removed in a selective catalytic reduction (SCR) process. SCR relies on the addition of ammonia (NH₃) as a reductant for nitrogen oxide (NO). DeNOx by SCR is often limited by a non-homogeneous distribution of NH₃ in the catalyst. This has two highly unwanted effects: (i) it leads to inefficient reduction of NO to N₂, and thus to high NOx emissions, sometimes even above the legal thresholds, and (ii) it increases the consumption of NH₃, produces unnecessary NH₃ slip and high costs. The distribution of NH₃ in a catalyst can be determined by FTIR grid measurements, which is subsequently also used to confirm the optimization of the NH₃ addition.