In this work (111)-oriented  metallic Pd nanoparticles supported on rutile TiO2(110) have been studied using the complementary techniques of STM and XPEEM. X-ray photoemission electron microscopy reveals that the nanoparticles are composed of metallic palladium, separated by the bare TiO2(110) surface. Quasi-hexagonal particles act as mimics for supported particles in catalysis. Here there is an interest in the interaction between adsorbate domain walls that are not present on single crystal surfaces. Using CO as a model adsorbate, we find domains of /3x/3-R30� at 0.33 ML, top-bridge and bridge-bridge c(4x2)-2CO at 0.5 ML,  as well as 2x2-3CO at 0.75 ML. Complex structures are formed at intermediate coverages, with domain walls between some adlayers and coexisting adlayers of differing symmetry. Fluxional behavior of domains is observed following STM tip pulses.

Domain walls of CO adlayers on Pd nanoparticles

Fullerenes are carbon-based nanomaterials present in the environment due to several natural events and due to the human activity, including combustion processes, car-brakes, etc. During the recent years a new source of fullerenes to the environment can be expected through the increasing development of nanotechnology. Thus, a general consensus exists in considering fullerenes as a new family of emerging pollutants [1]. Nevertheless, analytical methods for these compounds are somehow scarce [2-4], and their extraction from some environmental samples is especially difficult. Traditional extraction techniques have been applied for this purpose with limited success and laser-desorption ionization sources have been extensively applied for their mass spectrometric analysis despite little quantitative information can be achieved and they entail risk of fullerene self-generation. There is a need of developing reliable, robust, accurate quantitative methods which allow assessment of the occurrence of fullerenes in environmental matrices, specially in soils and sediments. Different analytical procedures based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) will be presented for the analysis of eight fullerenes: C60, C70, C76, C78 and C84 fullerene, C60 pyrrolidine tris-acid ethyl ester, [6,6]-Phenyl-C61 butyric acid butyl ester and [6,6]-Thienyl C61butyric acid methyl ester in environmental samples, including: airborne particulate, soils, sediments, combustion particles and wastewaters. The fate of fullerenes in 22 wastewater samples from Catalonia (Spain) and combustion particles from Brazil will be reported. In addition, the results of 28 samples of airborne particulate collected from the Mediterranean Sea atmosphere [3], and 12 soils from urban and industrial districts of four different Saudi Arabia locations (Riyadh, Al-Diriyah, Yanbu' Al Bahr and Jubail) will be presented and discussed. Higher fullerene concentrations are generally associated with higher levels of Polycyclic Aromatic Hydrocarbons and legacy Persistent Organic Pollutants, such as PCBs. Fullerene sources are associated with the emission from urban and industrialized areas being a possible risk to the environment.[1] Richardson S.D., 2010, Environmental Mass Spectrometry: Emerging Contaminants and Current Issues. Analytical Chemistry, 82, 4742-4774.[2] Sanch�s J. J Dachs, M Farre and D Barcelo 2012, Occurrence of Aerosol-Bound Fullerenes in the Mediterranean Sea Atmosphere, Environmental Science and Technology, 46, 1335-1343[3] Farr� M. L Kantiani , A Ginebreda and D Barcel� 2010, First determination of C60 and C70 fullerenes and N-methylfulleropyrrolidine C60 on the suspended material of wastewater effluents by liquid chromatography hybrid quadruple linear ion trap tandem mass spectrometry, Journal of Hydrology, 383,52-61[4] Barcel� D. and Farr� M., 2011, Characterization, analysis and risks of nanomaterials in environmental and food samples. TrAC Trends in Analyt

Fate and occurrence of fullerenes in airborne particulate, combustion particles, contaminated soils and wastewater samples

244th National Meeting (2012)

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