Fig. 1. Principle of attenuated total reflection

Fig. 2. Optical constants and attenuated total reflection spectra of pure water. (a) Optical constants of pure water and ZnSe; (b) attenuated total reflection spectra of pure water

Fig. 3. Experimental infrared spectra of dilute sodium carbonate solutions

Fig. 4. Spectra before and after baseline adjustment

Fig. 5. Linear relationship between absorbance and concentration at 1392.51 cm^-1 before and after baseline adjustment

Fig. 6. Optical constants of dilute sodium carbonate solutions before and after baseline adjustment

Fig. 7. Optical pathlength within the carbonate ions peak band after baseline adjustment

Fig. 8. Molar absorptivity before and after baseline adjustment

Fig. 9. Standard deviation of maximum molar absorptivity at different concentrations. (a) Before baseline adjustment; (b) after baseline adjustment