Abstract
The effect of addition of carbon dioxide to solvent properties such as polarity and hydrogen bond of supercritical water was studied using a high-temperature and high-pressure UV/Vis spectroscopy. From the solvatochromic shift of pyridazine, local density augmentation around pyridazine molecules was observed in the absence of carbon dioxide. However, in supercritical water with 1 mol% carbon dioxide, local density augmentation was found to be smaller, which suggests that carbon dioxide disturbs the interaction between water molecules. The frequency of maximum absorbance shifted to high frequency with an increase of carbon dioxide concentration. This result suggests that the hydrogen bond between pyridazine molecule and water molecule probably becomes stronger with increasing carbon dioxide concentration.
