: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Platinum-based nanostructured materials: synthesis, properties, and applications.

https://web.uvic.ca/~agbrolo/ACA_GFS_MF_2011.pdf

A review on the fabrication of substrates for surface enhanced Raman spectroscopy and their applications in analytical chemistry.

We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ∼0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR’s aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures.

Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives

We have investigated the reaction mechanism of the electrochemical reduction of carbon dioxide to hydrocarbons on copper electrodes. This reaction occurs via two pathways: a C1 pathway leading to methane, and a C2 pathway leading to ethylene. To identify possible intermediates in the reduction of carbon dioxide we have studied the reduction of small C1 and C2 organic molecules containing oxygen. We followed the formation and consumption of intermediates during the reaction as a function of potential, using online mass spectrometry. For the C1 pathway we show that it is very likely that CHOads is the key intermediate towards the breaking of the C–O bond and, therefore, the formation of methane. For the C2 pathway we suggest that the first step is the formation of a CO dimer, followed by the formation of a surface-bonded enediol or enediolate, or the formation of an oxametallacycle. Both the enediol(ate) and the oxametallacycle would explain the selectivity of the C2 pathway towards ethylene. This new mechanism is significantly different from existing mechanisms but it is the most consistent with the available experimental data.

A new mechanism for the selectivity to C1 and C2 species in the electrochemical reduction of carbon dioxide on copper electrodes

New mechanistic aspects of methanol oxidation

New insight into the pathways of methanol oxidation

Carbon monoxide oxidation at platinum electrodes in acid solutions presents a characteristic behavior depending on the presence or not of dissolved CO in the bulk of the solution. In the present paper, bulk CO electro-oxidation is studied on a Pt(111) electrode. A change of the (2 × 2)-3CO overlayer, formed by admitting CO at 0.05 V, into a (√19 × √19)-13CO structure was observed at around 0.4 V. These changes were monitored by in situ Fourier transform IR spectroscopy through the bands for on-top, 2-fold, and 3-fold bonded CO. If the solution is saturated with CO, oxidation of the CO adlayer formed at 0.05 V begins at ca. 0.4 V and presents a “quasistationary” behavior. This process involves weakly bonded CO. The presence of such species is rationalized in terms of the steep decrease of the desorption energy at high degrees of coverage, reported for CO adlayers on Pt(111) in UHV. When CO is adsorbed at high potentials (above 0.6 V), segregated adlayers of CO and H-bonded H2O are formed. The H-bonded H2O ...

E.A. Batista

Papers

New mechanistic aspects of methanol oxidation

New insight into the pathways of methanol oxidation

Mechanism of Stationary Bulk CO Oxidation on Pt(111) Electrodes

Analysis of FTIRS data and thermal effects during methanol oxidation on UHV-cleaned PtRu alloys

Catalysis of formaldehyde oxidation by electrodeposits of PtRu