[Evidence of discontinuities in the Raman spectra of aqueous NaCl solution at high pressure].

ABSTRACT

In-situ Raman spectra measurement for aqueous NaCl solution was conducted at the temperature of 21 degrees C and the pressures of 50-1 100 MPa using a SiC anvil cell. It is shown that the decomposed bands of aqueous NaCl solution shift to lower wavenumber with increasing pressure initially and reaches the minimum at about 300 MPa, and increases at higher pressure up to about 800 MPa, then decreases again with increasing pressure. Similarly, the ratio of band-area and the width at half maximum of the decomposed bands of the solution exhibit discontinuities at about 300 and 800 MPa. This finding demonstrates that the structure of aqueous NaCl solution is discontinuous at high pressure and O-H...Cl- bonds change correspondingly, which suggests the existence of rearrangement and the appearance of more complicated configuration in the interior structrure of aqueous NaCl solution.