@article {128,
	title = {Atomic Force Microscopy and X-ray Photoelectron Spectroscopy Study of NO2 Reactions on CaCO3 (101̅4) Surfaces in Humid Environments.},
	journal = {Journal of Physical Chemistry A},
	volume = {116},
	year = {2012},
	note = {CAPLUS AN 2012:1112006(Journal; Online Computer File)},
	pages = {9001 - 9009},
	publisher = {American Chemical Society},
	abstract = {A.c. (a.c.) mode at. force microscopy (AFM) combined with phase imaging and XPS were used to study the effect of nitrogen dioxide (NO2) adsorption on calcium carbonate (CaCO3) (101̅4) surfaces at 296 K in the presence of relative humidity (RH).  At 70\% RH, CaCO3 (101̅4) surfaces undergo rapid formation of a metastable amorphous calcium carbonate layer, which in turn serves as a substrate for recrystn. of a nonhydrated calcite phase, presumably vaterite.  The adsorption of nitrogen dioxide changes the surface properties of CaCO3 (101̅4) and the mechanism for formation of new phases.  In particular, the 1st calcite nucleation layer serves as a source of material for further island growth; when it is depleted, there is no change in total vol. of nitrocalcite, Ca(NO3)2, particles formed whereas the total no. of particles decreases.  These particles are mobile and coalesce.  Phase imaging combined with force curve measurements reveals areas of inhomogeneous energy dissipation during the process of water adsorption in relative humidity expts., as well as during nitrocalcite particle formation.  Potential origins of the different energy dissipation modes within the sample are discussed.  Finally, XPS anal. confirms that NO2 adsorbs on CaCO3 (101̅4) as nitrate (NO3-) regardless of environmental conditions or the pretreatment of the calcite surface at different relative humidity. [on SciFinder(R)]},
	keywords = {atomic force microscopy XPS nitrogen oxide adsorption calcium carbonate},
	isbn = {1089-5639},
	author = {Baltrusaitis, Jonas and Grassian, Vicki H.}
}
@article {182,
	title = {Adsorption of sulfur dioxide on hematite and goethite particle surfaces.},
	journal = {Physical Chemistry Chemical Physics},
	volume = {9},
	year = {2007},
	note = {CAPLUS AN 2007:1196084(Journal)},
	month = {2007///},
	pages = {5542 - 5554},
	publisher = {Royal Society of Chemistry},
	abstract = {The adsorption of sulfur dioxide (SO2) on iron oxide particle surfaces at 296 K has been investigated using XPS.  A custom-designed XPS ultra-high vacuum chamber was coupled to an environmental reaction chamber so that the effects of adsorbed water and mol. oxygen on the reaction of SO2 with iron oxide surfaces could be followed at atmospherically relevant pressures.  In the absence of H2O and O2, exposure of hematite (α-Fe2O3) and goethite (α-FeOOH) to SO2 resulted predominantly in the formation of adsorbed sulfite (SO32-), although evidence for adsorbed sulfate (SO42-) was also found.  At satn., the coverage of adsorbed sulfur species was the same on both α-Fe2O3 and α-FeOOH as detd. from the S2p:Fe2p ratio.  Equivalent satn. coverages and product ratios of sulfite to sulfate were obsd. on these oxide surfaces in the presence of water vapor at pressures between 6 and 18 Torr, corresponding to 28 to 85\% relative humidity (RH), suggesting that water had no effect on the adsorption of SO2.  In contrast, mol. oxygen substantially influenced the interactions of SO2 with iron oxide surfaces, albeit to a much larger extent on α-Fe2O3 relative to α-FeOOH.  For α-Fe2O3, adsorption of SO2 in the presence of mol. oxygen resulted in the quant. formation of SO42- with no detectable SO32-.  Furthermore, mol. oxygen significantly enhanced the extent of SO2 uptake on α-Fe2O3, as indicated by the greater than two-fold increase in the S2p:Fe2p ratio.  Although SO2 uptake is still enhanced on α-Fe2O3 in the presence of mol. oxygen and water, the enhancement factor decreases with increasing RH.  In the case of α-FeOOH, there is an increase in the amt. of SO42- in the presence of mol. oxygen, however, the predominant surface species remained SO32- and there is no enhancement in SO2 uptake as measured by the S2p:Fe2p ratio.  A mechanism involving mol. oxygen activation on oxygen vacancy sites is proposed as a possible explanation for the non-photochem. oxidn. of sulfur dioxide on iron oxide surfaces.  The concn. of these sites depends on the exact environmental conditions of RH. [on SciFinder(R)]},
	keywords = {adsorption sulfur dioxide hematite goethite particle surface},
	isbn = {1463-9076},
	author = {Baltrusaitis, Jonas and Cwiertny, David M. and Grassian, Vicki H.}
}
