Understanding the effects of chlorine ion on water structure from a Raman spectroscopic investigation up to 573 K

Abstract

The OH stretch band features on Raman spectra of aqueous KCl−H2O solutions have been investigated at temperatures (T) up to 573 K. KCl greatly reduces the relative intensity of the shoulder at ∼3245 cm−1 and the band width, but these effects are slightly reversed at temperatures over ∼513 K. Also, KCl causes a blue shift (T < 433 K) but a red shift (T > 433 K) of the main peak. These spectral features are interpreted that Cl− breaks the tetrahedral hydrogen bonding (HB) structure and bonds to water molecules with the non-tetrahedral HB configurations. The single donor is likely the preferred configuration between the water molecules in the Cl− hydration shells. Cl− tends to promote the HB degree in solutions at T > 433 K.