The Raman spectrum of aqueous nitrate is dependent on the laser intensity of the spectrometer.  This dependence appears as splitting of the symmetric stretch peak at high powers, although Raman spectra of that mode do not usually show multiple peaks.  Here, Raman spectra of nitrate solutions with different ionic strengths and concentrations were collected at varying laser intensities, to establish whether the observed intensity-dependence is related to the ionic strength of the solution, possibly through distortion of the molecular geometry.  Similar peak-splitting is observed in all the solutions, but seem to be less prominent in the high-ionic strength case.  The same measurements were also made using carbonate, which is expected to behave like nitrate because it has similar structure.  Power and ionic strength dependence are observed for it as well.  When these relationships are fully characterized, they may provide a convenient way to indirectly measure the ionic strength of nitrate solutions, which in turn would help establish reaction mechanisms involving nitrate ion in the natural environment.

Laser intensity and ionic strength dependence of the aqueous nitrate and carbonate ion Raman spectra

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.