Defective continuous hydrogen-bond networks: An alternative interpretation of IR spectroscopy

We apply our previously developed deconvolution method and interpretation to analyze changes in the OH stretching band [nu(OH) bond] of low-concentration (<= 0.2 m) aqueous solutions of NaCl and KCl. We treat these simple, monovalent ions as defects in the hydrogen-bond network of pure water and quantify the changes in the spectra at low defect concentration with on order parameter. Order-parameter analysis of difference spectra of the two solutions leads to hydration numbers of 70 +/- 7.0 and 5.9 +/- 0.3 for K+ and Na+, respectively. Additionally, we find that changes in the nu(OH) bond due to low concentrations of ions result from changes in the topology of the hydrogen-bond network.