LAUSR

Abstract We devised a new data analysis methodology for Near Infrared spectroscopic data of aqueous solutions. We first isolate the non-ideal (i.e. real) part of the results as the excess molar absorptivity, e E , then define and calculate the excess partial molar absorptivity of solute, e S E , the effect of solute (S) on the excess molar absorptivity, e E . By using these, we learned that there are three universal chromophores in the ν 2  +  ν 3 combination band of H 2 O in the e E spectra of aqueous solutions of the total nine electrolytes. Furthermore, we learned from the excess partial molar absorptivity, e S E , we identified a specific chromophore out of three that distinguish the specific characteristics of a given solute on H 2 O. Here we add an evidence for the universality of three bands in e E to include two examples of ionic liquids. In addition, using the literature data, we show that the ν 1 overtone of H 2 O in NaCl – H 2 O and CaCl 2 – H 2 O also have a limited number of universal chromophores at the same wave numbers in their e E spectra.