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Solid state and solution nitrate photochemistry: Photochemical evolution of the solid state lattice

Asher, SA and Tuschel, DD and Vargson, TA and Wang, L and Geib, SJ (2011) Solid state and solution nitrate photochemistry: Photochemical evolution of the solid state lattice. Journal of Physical Chemistry A, 115 (17). 4279 - 4287. ISSN 1089-5639

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Abstract

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 π → π* 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.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Asher, SAasher@pitt.eduASHER
Tuschel, DD
Vargson, TA
Wang, L
Geib, SJgeib@pitt.eduGEIB0000-0002-9160-7857
Date: 5 May 2011
Date Type: Publication
Journal or Publication Title: Journal of Physical Chemistry A
Volume: 115
Number: 17
Page Range: 4279 - 4287
DOI or Unique Handle: 10.1021/jp200406q
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 1089-5639
MeSH Headings: Nitrates--chemistry; Photochemistry; Solutions; Spectrum Analysis, Raman; Ultraviolet Rays
PubMed ID: 21462986
Date Deposited: 08 Feb 2013 20:50
Last Modified: 22 Jun 2021 14:55
URI: http://d-scholarship.pitt.edu/id/eprint/17251

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