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Potential energy curves are produced for the halogen bonding interactions of several halobenzene-formaldehyde complexes. The results have shown that for most halogen substituents, a halobenzene and formaldehyde form stable halogen bonded complexes with interaction energies that increase as the size of the halogen substituent increases.

Little is known about the isotopic composition of formaldehyde in the atmosphere, a chemical intermediate in hydrocarbon oxidation. Here, we present a promising new method to analyze the carbon ([[delta].sup.13]C) and hydrogen ([delta]D) isotopic composition of atmospheric formaldehyde. The direct isotopic analytical technique described uses continuous-flow gas chromatography--isotope ratio mass spectrometry, which provides flexibility for either isotopic analysis without correction for derivative functional groups. Current levels of precision of measurement are [+ or -]1.1 and [+ or -] 50[per thousand] (1[sigma]) for [[delta].sup.13]C and [delta]D analyses, respectively. Concentration of formaldehyde in ambient air is also determined, coincident with isotopic measurement, to a precision of [+ or -] 15%. The method has the required sensitivity for analyses of formaldehyde in urban air on relatively small volume grab samples of whole air (10-70L STP), potentially providing high temporal resolution. This is particularly advantageous for studying formaldehyde given its short lifetime and large variability in the atmosphere.

Neural networks (NNs) are efficient and effective tools for fitting potential energy surfaces. A nested neural network technique is developed, which is as a choice for both simple potentials, for which it is relatively easy to guess a good fitting function, and complicated, double well potentials for which it is much harder to deduce an appropriate fitting function.

The thermal chemistry of formaldehyde on vanadium (100) single-crystal surfaces is analyzed under ultrahigh vacuum (UHV) conditions by using temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) in combination with isotope-labeling experiments. The low-temperature reaction has occurred via the coupling of methylene groups formed on the surface upon dissociation of the C-O bond in adsorbed formaldehyde and the high-temperature ethylene has required the prior formation of a diolate intermediate.

The cluster model approach was used to study formaldehyde adsorption on models of the (111) surface of palladium and of palladium supported on the (110C) surface of [gamma]-[Al.sub.2][O.sub.3]. The analysis from natural bond orbital (NBO) showed that the highly coordinated octahedral aluminum atoms of [Al.sub.10][O.sub.15] donate electron density to the supported P[d.sub.4] cluster, while tetrahedral aluminum atoms with lower coordination number have acidic nature.

The systematic characterization of two series of small polyatomic ions, [H.sub.x][CO.sup.+] and [H.sub.x][N.sub.2.sup.+] (x = 1, 2, 3) is described. The differing mechanism for dissociation of the larger ions through hydrogen abstraction and dissociation of triatomic ions by proton abstraction provide insight into large differences in the abundances of H[N.sub.2.sup.+] and H[CO.sup.+] observed in inductively coupled plasma mass spectrometry (ICP-MS) experiments.

The mechanism of methanol oxidation to formaldehyde by ironoxido is studied using density functional theory calculations on microsolvated clusters in the gas phase and by simulations in water solution. It is seen that the methanol molecule forms a complex bond with the oxido group resulting in formation of an OH ligand and weak C[H.sub.2]OH radical followed by the transfer of the H of the hydroxyl group to the OH ligand to from an [H.sub.2]O ligand.

Carbon nanotubes (CNTs) based hollow capsules are obtained by degradation under acidic conditions of core-shell nanocomposites build up upon adsorption of multilayers of CNTs onto melamine-formaldehyde (MF) spheres. The proposed route for the formation of fractal-like structures is based on the role of the capsules as arrangements of heterogeneities that facilitate the dewetting of the liquid polymeric films.

High-level ab initio molecular orbital methods were used to investigate the reaction between C[H.sub.2]O and ClO and to map out the complete potential energy surface (PSE) for the system. The calculated results demonstrated that the formation of HOCl+HCO was the dominant reaction channel and was exothermic suggesting that the decomposition in both the forward and backward directions for HOCl would be difficult in the ground electronic state.

Density functional slab model calculations are used to study the decomposition of formaldehyde, a key intermediate in methanol decomposition and steam reforming reactions, on planar surfaces of Pd, Cu and PdZn as well as on a stepped surface of PdZn. The experimentally observed small amount of CO, formed during steam reforming of methanol on the Pd/ZnO catalyst, is ascribed to occur at metallic Pd species of the catalyst or at defect sites of PdZn alloy.

A commercially-available HCHO-analyzer is used to measure the gas-liquid phase partitioning of a nonideal, solute-solvent mixture. The experiment is applied to demonstrate nonideal, biphase thermodynamic equilibrium and concentration and temperature effects are studied to demonstrate factors affecting the thermodynamic ratio.