Figure 1
From: Revealing excess protons in the infrared spectrum of liquid water
Experimental spectra of dynamical conductivity \(\sigma (\nu )\) of (A) pure light and pure heavy water, (B) mixtures of light and heavy water with different molar isotopic fractions f as indicated, (C) pure HDO calculated using Eq. (1), and (D,E) magnified parts of the HDO spectra near the \(\hbox {D}{-}\hbox {O}{-}\hbox {D}\) and \(\hbox {H}{-}\hbox {O}{-}\hbox {H}\) bending modes showing “S-shaped” mismatches (see text). The spectra for \(f=1/2\) and \(f=1/4\) in panels (C–E) are shifted upwards for clarity. Thin arrows show two stretching modes above \(2{,}000\,\hbox {cm}^{-1}\), and three bending modes below \(2{,}000\, \hbox {cm}^{-1}\). Vertical lines are guides for the eye. Thick arrows indicate the areas, where the mismatches of the spectra, \(S_1\) and \(S_2\), occur.
