Influence of measuring conditions on the quantification of spectroscopic signals in TA-FTIR-MS systems

A novel direct coupling of simultaneous thermal analysis (STA) and Fourier transform-infrared (FT-IR) spectroscopy

“…18. The observed nonlinearity is significantly stronger than reported by Eigenmann et al [12]. For H 2 O, the data Fig.…”

“…In contrast, the areas of the Gram-Schmidt traces were practically not proportional to the mass loss which means that the Gram-Schmidt trace does not appear to be suitable for quantification of evolved gases-at least not when several gases are evolved at the same time. In summary, a proper quantification of evolved gases is feasible when taking into account possible nonlinearity [12]. The simplest way is certainly to work in the linear regime which should, however, be confirmed by several measurements.…”

“…For a correct quantification of evolved gases, the linearity of the detected FT-IR absorbance should be considered [12]. Figure 18 shows that for example in case of CO 2 , the absorbance at 2,357 cm -1 , where maximum absorbance for CO 2 occurs, is strongly nonlinear.…”

“…Figure 18 shows that for example in case of CO 2 , the absorbance at 2,357 cm -1 , where maximum absorbance for CO 2 occurs, is strongly nonlinear. The origin of nonlinearity is presumably the finite spectral resolution of the FT-IR detection and furthermore deviation from Lambert-Beer's law due to molecule-molecule interactions at higher concentrations [12,13]. Approximately linear behavior was observed at concentrations below about 1 % (see inset of Fig.…”

“…In typical sample measurements, the relevance of nonlinearity depends on the experimental conditions like the sample mass, the heating rate, the flow rate of the purge gas, and furthermore the spectral resolution, acquisition rate and the evaluated wave number region of the FT-IR measurement [12]. Exemplary results are displayed in Fig.…”