## 3 Results and Discussion
### Humidity Control Experiments in Spectroscopic Equipment  
The humidity and temperature profiles inside the IRS FTIR spectrometer are given in Figure 7, while the exponential decay fitting parameters of the humidity curves for the three dehumidifying configurations are given in Table 2. Starting from a humidity level of around 40-43%, the combined configuration decreased the humidity to around 15%, while the desiccant bags and the membrane reached only 19% and 22%, respectively, with the exponential fit predicting values of c of 14.2% RH, 17.6% RH and 20.8% RH for the three configurations. Again, the combined configuration can not only secure lower humidity levels, but it is also faster, reaching its half value compared to its plateau in 21.21 min. In this experiment, the membrane configuration was also slower compared to the three-desiccant-bag configuration, at t\({}_{1/2}\) = 26.87 min, compared to t\({}_{1/2}\) = 24.29 min. The temperature inside the 35.4 L volume was kept relatively stable at 21-23 \({}^{\circ}\)C over  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{**70 L Box–High Humidity**} & \multicolumn{2}{c}{**230 L Box–High Humidity**} \\ \hline  & **Membrane** & **Membrane \& **2 Silica** & **4 Silica Desiccant** & **Membrane** & **Membrane \& **4 Silica Desiccant Bags** \\ \hline R\({}^{2}\) & 0.947 & 0.981 & 0.978 & 0.998 & 0.968 \\ \hline a & 55.4 & 53.1 & 46.7 & 49.6 & 47.5 \\ \hline b & 0.546 & 1.029 & 0.231 & 0.065 & 0.233 \\ \hline c & 15.7 & 15 & 26.9 & 26.9 & 22 \\ \hline \(\tau\) & 1.83 & 0.97 & 4.  
the span of 90 min despite the continuous operation of the silicon carbide light source of the spectrometer. Figure 8 shows the background spectrum of the air-tight IR5 FTIR spectrometer in the 4000-1000 cm\({}^{-1}\) region at two different internal relative humidity levels, with a maximum resolution setting of 0.5 cm\({}^{-1}\). In red, the spectrum with 42.5% RH humidity, before applying dehumidifying strategies, is shown. In blue, we give the spectrum at 15.1% RH after using the combined dehumidifying configuration incorporating the M-J1 IR and the three desiccant bags sized 0.1 L each. These spectra show the absorption lines of the H\({}_{2}\)O and CO\({}_{2}\) atmospheric gases that were present in the optical path of the infrared beam before it reached the detector. The absorption lines around 3700 cm\({}^{-1}\) (stretching modes) and 1500 cm\({}^{-1}\) (bending modes) correspond to H\({}_{2}\)O absorption, while the lines around 2350 cm\({}^{-1}\) correspond to CO\({}_{2}\) absorption (asymmetric stretching mode). The H\({}_{2}\)O absorption lines were greatly reduced at 15.1% RH, but they remained present in different spectral regions. While the weak absorption lines between 3500-3000 cm\({}^{-1}\) and 2000-1900 cm\({}^{-1}\) almost disappeared, the stronger ones between 3900-3600 cm\({}^{-1}\) and 1800-1400 cm\({}^{-1}\) remained. Nevertheless, the stronger absorption lines are the ones that appear to show the highest percentage change. This can be seen in Figure 9, where the percentage change of the H\({}_{2}\)O absorption lines is plotted as a function of their wavenumbers. More specifically, the peak near 1652.93 cm\({}^{-1}\) shows a 95% relative change, while the \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**IR5 FTIR SPECTROMETER**} \\ \hline \multicolumn{4}{c}{**3 Silica Desiccant Bags**} & \multicolumn{2}{c}{**Membrane**} & \multicolumn{2}{c}{**Membrane \& 3 Silica Desiccant Bags**} \\ \hline R\({}^{2}\) & 1 & 0.999 & 0.999 \\ \hline a & 22.3 & 18.8 & 28 \\ \hline b & 0.028 & 0.026 & 0.033 \\ \hline c & 17.6 & 20.8 & 14.2 \\ \hline \(\tau\) & 35.34 & 38.76 & 30.6 \\ \hline \(\tau_{1/2}\) & 24.49 & 26.87 & 21.21 \\ \hline \end{tabular}
\end{table} 
Table 2: Exponential decay fitting parameters for the data from Figure 6. The time units are in minutes.