Additional Departmental Affiliation
Physics and Astronomy
The geometry (and hence vibrational modes) of aqueous nitrate ion, NO3-, is known to depend on the solution composition—concentration, counter ions, etc. If a definite relationship between the vibrational spectrum and ionic strength of the solution could be established, it could be a useful monitor of solution composition over time. This would be valuable in studying the reaction rates and mechanisms of reactions involving nitrate in an aqueous environment, such as its photolysis in snow. Previous work in our lab observed a split peak at the symmetric-stretch mode of nitrate, though this mode does not usually show multiple peaks. The degree of peak splitting varied with time after photolysis (possibly indicating composition dependence) and also with the laser power of the spectrometer. In this project, Raman spectra of several different nitrate and carbonate solutions were collected over a range of laser powers, in order to relate the power-dependent peak splitting to the solution composition. To check results, the experiments were repeated on a second instrument. While the first spectrometer consistently showed peak-splitting, the effect was not reproducible on the second spectrometer, and so not likely to be useful as a probe of ionic strength.
Advisor(s) or Committee Chair
Dr. Matthew Nee
White, Samuel, "Laser Intensity and Ionic Strength Dependence of the Aqueous Nitrate and Carbonate Ion Raman Spectra" (2014). Honors College Capstone Experience/Thesis Projects. Paper 491.