TY  - JOUR
ID  - pittir17251
UR  - http://d-scholarship-dev.library.pitt.edu/17251/
IS  - 17
A1  - Asher, SA
A1  - Tuschel, DD
A1  - Vargson, TA
A1  - Wang, L
A1  - Geib, SJ
Y1  - 2011/05/05/
N2  - We examined the deep UV 229 nm photochemistry of NaNO3 in solution and in the solid state. In aqueous solution excitation within the deep UV NO3- strong ? ? ?* transition causes the photochemical reaction NO3- ? NO2- + O·. We used UV resonance Raman spectroscopy to examine the photon dose dependence of the NO2- band intensities and measure a photochemical quantum yield of 0.04 at pH 6.5. We also examined the response of solid NaNO3 samples to 229 nm excitation and also observe formation of NO2-. The quantum yield is much smaller at ?10-8. The solid state NaNO3 photochemistry phenomena appear complex by showing a significant dependence on the UV excitation flux and dose. At low flux/dose conditions NO2- resonance Raman bands appear, accompanied by perturbed NO3- bands, indicating stress in the NaNO3 lattice. Higher flux/dose conditions show less lattice perturbation but SEM shows surface eruptions that alleviate the stress induced by the photochemistry. Higher flux/dose measurements cause cratering and destruction of the NaNO3 surface as the surface layers are converted to NO2-. Modest laser excitation UV beams excavate surface layers in the solid NaNO3 samples. At the lowest incident fluxes a pressure buildup competes with effusion to reach a steady state giving rise to perturbed NO3- bands. Increased fluxes result in pressures that cause the sample to erupt, relieving the pressure. © 2011 American Chemical Society.
JF  - Journal of Physical Chemistry A
VL  - 115
SN  - 1089-5639
TI  - Solid state and solution nitrate photochemistry: Photochemical evolution of the solid state lattice
SP  - 4279 
AV  - public
EP  -  4287
ER  -