[Effects of cations in chlorine salt solution on O-H stretching Raman spectra of water].

In order to understand the effects of the common cations in geofluids on the structure of water, the present paper systematically studied the Raman spectra of NaCl-H2O, CaCl2-H2O, MgCl2-H2O, CuCl2-H2O, ZnCl2-H2O and FeCl3-H2O solutions by two methods. (1) The frequency shifts of the peak maximum around 3,400 cm(-1) in O-H stretching Raman spectra of water reveal the destruction effects of these cations on the structure of water: Ca2+ > Mg2+ > Na+, Fe3+ > Zn2+ > Cu2+; (2) Comparing the intensities of the shoulder peak around 3,250 cm(-1) in the O-H stretching Raman spectra of water: (1) all salts concerned destruct the structure of water; (2) with respect to the same chloride, the destruction extent of hydrogen-bond increases with concentration increasing; (3) comparing different chloride solutions at the same concentration, the destruction effects of catnions on the structure of water decrease in the sequences Ca2+ > Mg2+ > Na+ and Fe3+ > Zn2+ > Cu2+. (4) A hydrogen bond-affected mechanism combining cation destruction with complex compound production is supposed for the first time, and is used to explain the effects of the canions on the structure of water: CaCl2 > MgCl2 > FeCl3 > NaCl > ZnCl2 > CuCl2.