@article{BsdokAltenbergerConchaPerdomoetal.2020, author = {Bsdok, Barbara and Altenberger, Uwe and Concha-Perdomo, Ana Elena and Wilke, Franziska Daniela Helena and Gil-Rodriguez, J. G.}, title = {The Santa Rosa de Viterbo meteorite, Colombia}, series = {Journal of South American earth sciences}, volume = {104}, journal = {Journal of South American earth sciences}, publisher = {Elsevier Science}, address = {Amsterdam}, issn = {0895-9811}, doi = {10.1016/j.jsames.2020.102779}, pages = {8}, year = {2020}, abstract = {Undifferentiated meteorites, like primitive chondrites, can contain presolar and solar nebula materials which would provide information about the origin and initial conditions of the solar system, whereas differentiated meteorites like iron meteorites, can show early phases of planetary accretion. They also provide the possibility to receive information about core properties and planetary bodies. In addition to the gain in such fundamental scientific knowledge both types are of interest for the exploration of critical raw materials (CRMs) and precious elements. The Santa Rosa de Viterbo meteorite shower, discovered 1810 in the Boyaca province of Colombia, represents a typical iron-nickel meteorite. The present study presents new structural, textural and geochemical results of one fragment of this meteorite, using reflecting microscopy, electron probe micro analyses (EPMA) and electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The present study presents trace element concentrations of the meteorite's minerals for the first time. The sample is dominated by kamacite (alpha-FeNi). Schreibersite (FeNi3P), taenite (gamma-FeNi) and plessite (mixture of kamacite and taenite) are minor constituents. The occurrence of cohenite ((Fe,Ni,Co)(3)C) and troilite (FeS) are likely. The meteorite sample contains classical Neuman bands passing through kamacite and frequent Widmanstadtten pattern. The bandwidth of kamacite defines the meteorite as finest octahedrite. Geochemically, it is characterized as a "Type IC meteorite". While improving the characterization and classification of the Santa Rosa de Viterbo Iron Meteorite, notable concentrations of Au (>400 ppm) and Ge (>230 ppm) alongside major elements such as Fe, Ni and Co in the bulk composition of that meteorite, were proven. Major and rock-forming minerals such as kamacite and taenite incorporate hundreds of ppm of Ge whereas schreibersite, itself a minor component in that particular meteorite, is the major source for Au (>1400 ppm). In kamacite and taenite also Ir, Pd and Ga were found in minor amounts. Nano-scale inclusions or atomic clusters called nano-nuggets may have been responsible for the high concentrations of Au, Ir, Pd and Ga. Raman and Laser-induced plasma spectroscopes installed in in space probes seems suitable exploration methods for Fe-Ni meteorites, containing Ni-concentrations > 5.8 wt\% defining the meteorite as octaedrites.}, language = {en} } @article{SarhanKoopmanPudelletal.2019, author = {Sarhan, Radwan Mohamed and Koopman, Wouter-Willem Adriaan and Pudell, Jan-Etienne and Stete, Felix and R{\"o}ssle, Matthias and Herzog, Marc and Schmitt, Clemens Nikolaus Zeno and Liebig, Ferenc and Koetz, Joachim and Bargheer, Matias}, title = {Scaling up nanoplasmon catalysis}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {123}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {14}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.8b12574}, pages = {9352 -- 9357}, year = {2019}, abstract = {Nanoscale heating by optical excitation of plasmonic nanoparticles offers a new perspective of controlling chemical reactions, where heat is not spatially uniform as in conventional macroscopic heating but strong temperature gradients exist around microscopic hot spots. In nanoplasmonics, metal particles act as a nanosource of light, heat, and energetic electrons driven by resonant excitation of their localized surface plasmon resonance. As an example of the coupling reaction of 4-nitrothiophenol into 4,4′-dimercaptoazobenzene, we show that besides the nanoscopic heat distribution at hot spots, the microscopic distribution of heat dictated by the spot size of the light focus also plays a crucial role in the design of plasmonic nanoreactors. Small sizes of laser spots enable high intensities to drive plasmon-assisted catalysis. This facilitates the observation of such reactions by surface-enhanced Raman scattering, but it challenges attempts to scale nanoplasmonic chemistry up to large areas, where the excess heat must be dissipated by one-dimensional heat transport.}, language = {en} } @article{CuiXiaMitzscherlingetal.2015, author = {Cui, Qianling and Xia, Bihua and Mitzscherling, Steffen and Masic, Admir and Li, Lidong and Bargheer, Matias and Moehwald, Helmuth}, title = {Preparation of gold nanostars and their study in selective catalytic reactions}, series = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, volume = {465}, journal = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2014.10.028}, pages = {20 -- 25}, year = {2015}, abstract = {In this work, gold nanostars (AuNSs) with size around 90 nm were prepared through an easy one-step method. They show excellent catalytic activity and large surface-enhanced Raman scattering (SERS) activity at the same time. Surprisingly, they exhibited different catalytic performance on the reduction of aromatic nitro compounds with different substituents on the para position. To understand such a difference, the SERS spectra were recorded, showing that the molecular orientation of reactants on the gold surface were different. We anticipate that this research will help to understand the relationship of the molecular orientation with the catalytic activity of gold nanoparticles.}, language = {en} } @article{VidadalaPimpalpalleLinkeretal.2011, author = {Vidadala, Srinivasa Rao and Pimpalpalle, Tukaram M. and Linker, Torsten and Hotha, Srinivas}, title = {Gold-Catalyzed reactions of 2-C-Branched carbohydrates mild glycosidations and selective anomerizations}, series = {European journal of organic chemistry}, journal = {European journal of organic chemistry}, number = {13}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {1434-193X}, doi = {10.1002/ejoc.201100134}, pages = {2426 -- 2430}, year = {2011}, abstract = {2-C-branched methyl glycosides react with various alcohols under gold catalysis to transglycosylated products. The method is applicable for the convenient synthesis of disaccharides. Without nucleophile a selective anomerization occurs, giving first access to alpha-configured 2-C-nitromethyl glycosides. The results are interesting for the mechanism of gold-catalyzed glycosidations.}, language = {en} }