The limited extent of the electronic modulation of chlorins and bacteriochlorins through chromene-annulation.

Optical data (UV-vis absorption and fluorescence emission spectra, including fluorescence yields and lifetimes) and electrochemical measurements are used to quantify the modulation of the electronic properties of meso-tetrakis(pentafluorophenyl)-chlorin diol and -bacteriochlorin tetraols upon intramolecular chromene-annulation, including the investigation of regio- and stereoisomers. The small modulations of the frontier orbitals of the porphyrinoids are rationalized using DFT computations and can be traced to small electronic effects due to the co-planarized meso-aryl groups in combination with conformational effects.

Attachment of Pt nanoparticles to a metal oxide surface using a thiol-carboxyl bifunctional molecule.

Hypothesis: Molecular attachments to platinum have received far less study than binding to gold. Of particular interest is whether the binding of bifunctional molecules, containing both thiol and carboxyl groups, can attach platinum to surfaces such as metal oxides.

Experiments: Attachment of 4-mercaptobenzoic acid (4-MBA) to bulk and nanoparticulate platinum was studied by cyclic voltammetry (CV), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS).

Photocatalytic effects of titanium dioxide nanoparticles on aquatic organisms-Current knowledge and suggestions for future research.

Nanoparticles are entering natural systems through product usage, industrial waste and post-consumer material degradation. As the production of nanoparticles is expected to increase in the next decade, so too are predicted environmental loads. Engineered metal-oxide nanomaterials, such as titanium dioxide, are known for their photocatalytic capabilities.

Morphological Characterization of ALD and Doping Effects on Mesoporous SnO2 Aerogels by XPS and Quantitative SEM Image Analysis.

Atomic layer deposition (ALD) is unsurpassed in its ability to create thin conformal coatings over very rough and/or porous materials. Yet although the coating thickness on flat surfaces can be measured by ellipsometry, characterization of these coatings on rough surfaces is difficult. Here, two techniques are demonstrated to provide such characterization of ALD-coated TiO2 over mesoporous SnO2 aerogel films on glass substrates, and insights are gained as to the ALD process.

Blue and white light emission from zinc oxide nanoforests.

Blue and white light emission is observed when high voltage stress is applied using micrometer-separated tungsten probes across a nanoforest formed of ZnO nanorods. The optical spectrum of the emitted light consistently shows three fine peaks with very high amplitude in the 465-485 nm (blue) range, corresponding to atomic transitions of zinc. Additional peaks with smaller amplitudes in the 330-650 nm range and broad spectrum white light is observed depending on the excitation conditions.

Transparent conducting aerogels of antimony-doped tin oxide.

Bulk antimony-doped tin oxide aerogels are prepared by epoxide-initiated sol-gel processing. Tin and antimony precursors are dissolved in ethanol and water, respectively, and propylene oxide is added to cause rapid gelation of the sol, which is then dried supercritically. The Sb:Sn precursor mole ratio is varied from 0 to 30% to optimize the material conductivity and absorbance.

Narrow-band irradiation of a homologous series of chlorophenols on TiO2: charge-transfer complex formation and reactivity.

The goal of this research was to investigate the formation and reactivity of charge-transfer complexes (CTCs) among a homologous series of chlorophenols on TiO2. We previously showed that 2,4,5-trichlorophenol (245TCP) forms a CTC with Degussa P25, a commercial preparation of TiO2. Here, we probe how light energy influences reactivity and product formation.