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The surface chemistry of thiophene on reduced and sulfided Ni/SiO2 and Ni2P/SiO2 catalysts is investigated by using infrared (IR) spectroscopy. The increased reactivity of thiophene on Ni2P/SiO2 catalysts in UHV may explain the high turnover frequency previously reported for Ni2P/SiO2 catalysts relative to sulfided Ni/SiO, Mo/SiO2, and Ni-Mo/SiO2 catalysts.

The study presents the use of single model that can be used as addition of promoter or poison species, which can destabilize the uniform state of surface chemical reactions. It is concluded that interplay between the reaction, interactions, and diffusion of species in this system could result in the development of periodic nonequilibrium spatial patterns.

The study characterizes the different Re-O species formed on O-modified planar and faceted Re surfaces and on a thin-film oxide on Re(1231). On the planar and faceted surfaces the study concluded that methanol reacts via competing pathways of dehydration to CH2O and CO and nonselective decomposition to yield H2 and CO formed by recombinative desorption.

A report on the surface phonon spectrum of the deuterium-terminated D:C(001)-(2*1) surface calculated using a semiempirical total energy approach is presented. The calculated mode energies are found to be in gratifying agreement with recent electron energy loss data and allow identifying the physical origin of the measured features.

Total energy calculations were performed for nitrous oxide and its anion N2O(super -) by Multi Configuration Self-Consistent Field-Configuration Interaction (MCSCF-CI) methods. For the purpose of studying the strong vibrational state dependence of the reaction outcome the study discusses transitions form the adiabatic N2O(super -) [(sub 2) A'] potential energy surface on the (super 2)A'' surface.

The prototypical photoreaction H(sub ad)+H( ad)->H(sub 2.gas) on Ru-(001) initiated by intense near-infrared femtosecond laser excitation is investigated. Detailed results on the influence and coverage dependence of the fs laser-induced hydrogen formation are presented.

It is shown that the loss of species on the reactor wall has to be taken into account while analyzing the kinetic results of the droplet-train apparatus. The uncertainty of the extracted gas-surface reaction and the probability for high water vapor experimental conditions have increased due to the revision of the kinetics for species with a wall loss.

The energy difference between the gauche and trans structures of ethanol is determined at the CCSD(T)/aug-cc-pVTZ level. Five classes of dimer structures exist due to the two monomer conformations. In a systematic way 600 structures were generated as initial structures for the dimer geometry optimization.

A computational kinetic Monte Carlo (KMC) experiments that examines the time scale and pathways of H-atom mobility across the step edges connecting (100), (110), and (111) surfaces and the time-scale and pathway of H-atom penetration in the sublayer of the surfaces is reported. The activation energies for H mobility from site-to-site using a realistic potential energy function are also determined.

The surface structures and segregation of ultrathin polystyrene (PS)

Hydration properties of organic and biomolecules are frequently calculated using continuum models. These models are also used to estimate its dependence on conformation and association. Nonpolar solvation contributions are often estimated from the solvent assessable surface of a molecule using a single surface tension parameter.

The potential energy surface for the C(super 3)P(sub j)) + C(sub 3)H(sub 5)(X (super 2)A(sub 1) reaction was investigated using ab initio G2M(MP2)//B3LYP/6-311G** calculations. The results indicate that C((super 3)P(sub j)) can add without a barrier either to the terminal CH(sub 2) group of the allyl radical to form a metastable intermediate INT1 or between two CH(sub 2) groups to produce a bicyclic structure INT2.

A theoretical study of the dynamics of the H + HC1system on the potential energy surface (PES) of Bian and Werner has been presented. State-to-state reaction probabilities for the exchanged and abstraction channels were calculated using a time-dependent wave pocket approach.

A simple genetic algorithm can efficiently search the space of surface-charge distributions in proteins and can find many stabilizing distributions under specified restrictions. It is shown that the genetic algorithm can be employed to select small sets of interacting sites to be used in vitro-directed evolution procedures.

A study of accurate single-valued double many-body expansion (DMBE) potential energy surface for the ground electronic state of HSO based on novel MR CISD ab initio energies suitably corrected for the complete one-electron basis-set/complete CI limit is presented. A n-body distributed polynomial approach, which implies using individual multinomial developments at the various stationary points is suggested.

A detailed investigation of the complex potential energy surface for the reaction of singlet methylene (CH2) with Nitrous oxide (N2O) using B3LYP/6-31G(d,p) and single point QCISD(T)/6-311G(d,p) methods is presented. This work can assist experiments to identify the products of the CH2+NO2 reaction.

The experiment shows that N2 chemisorbs at 88K on two stepped platinum surfaces, Pt(335) and Pt(779), with exclusive occupancy of step sites. An irreversible conversion from 2-D and 1-D precursor motion occurs as terrace-bound precursors irreversibly convert to step-bound precursors.

An attempt is made to investigate the adsorption of water on chemically modified, high surface area carbons by employing microcalorimetric techniques. Three mechanisms of water adsorption are detailed according to measured differential heats of adsorption (H (sub ads)).

Research is done on two classes of semiclassical methods for studying multielectronic-state dynamics, the trajectory surface-hopping (TSH) method and the time-dependent self-consistent field (TDSCF) method. In conclusion, several aspects of various nonadiabetic trajectory methods are shown pictorially.

Research is done on heterogeneous interaction of SO2 on both the H202-ice surface and the water-ice surface has been examined in a flow reactor interfaced with a differentially pumped quadrupole mass spectrometer. The results observed were that the uptake of SO2 on ice and snow surfaces was enhanced by the presence of H2O2 in ice at the temperature of the upper troposphere and lower stratosphere.

Atomic force microscopy (AFM) in contact mode was used in studying the reaction of single-crystal NaCl(100) with dry HNO3. The focus of the research is clarifying crystal growth in NaNO3. It has been previously reported that contact AFM is not destructive to NaCl or NaNO3 surfaces. Results show that exposures of NaCl(100) to large amounts of HNO3 with subsequent exposure to H2O leads to a surface containing rhombohedral NaNO3 crystals with the remaining surface as unreacted NaCl. The newly-exposed NaCl surface reacts further with HNO3 to form additional NaNO3.

The interaction of phthalic anhydride (I) with a clean and oxygen predosed Cu(100) surface has been studied using Fourier transform infrared spectroscopy between 95 to 300 K. I is used as a model system for studying other anhydride species such as pyrometallic dianhydride which are used in the production of polyimides. Results show that adsorption on a clean surface at 95 K is dominated by the intact planar molecule which is oriented parallel to the metal surface. A species without carbonyl and carboxylate functionalities is produced on warming.

X-ray photoelectron spectroscopy is used in studying the structure and bonding of azo-tert-butane (ATB) adsorbed on a Si(001) surface. It will be demonstrated that bonding of alkenes to Si(001) can be generalized for other unsaturated species. Adsorption onto a 130 K surface occurs with no bond cleavage although the formation of a completely ordered layer at room temperature is inhibited by slight cleavage of C-H bonds. Results indicate ATB bonds to the Si(001) surface through an interaction of the pi bond of the azo group with the pi bonds of Si-Si dimers. This results in the formation of two new Si-N sigma bonds.

This study examined the dynamics involved when an electronically nonadiabatic process couples to two underdamped vibrational degrees of freedom. Using numerical solutions of the multilevel Redfield equations, the analysis examined how the electronic population dynamics and product vibrational dynamics are affected by the degree to which the Franck-Condon active modes extend onto the reactive motion. Findings revealed that the competition between coherent vibrational motion and energy and phase relaxation generates electronic and nuclear dynamics that are sensitive to the location of and force acting on the initially prepared wave packet.

A study was conducted to analyze the oscillatory dynamics in droplets of the ferroin-catalyzed Belousov-Zhabotinsky solution. Small drops of the solution were pipetted into a glass Petri dish supporting a chemically inert silicone oil. Experimental results indicated that the phase oscillations supported a radial dependence that led to nontransient phase waves propagating from the center outward. Findings also showed the effectiveness of diffusive bromine removal from drops with a high surface-to-volume ratio.

An examination of the structure and bonding of 1,3,5,7-cyclooctatetraene (COT) with the silicon(001) surface was performed to address the dearth of research on the bonding of organic molecules to silicon surfaces. Findings revealed that a spontaneous ordering of the COT molecules on Si(001) occurs at room temperature, with each molecule separated by 7.7 angstrom. Moreover, the COT molecules bond to Si(001) through the direct interaction of two C=C units with two adjoining Si=Si dimers within an individual dimer row. Lastly, the lowest-energy geometry bonding of two C=C groups with two S=S dimers is a di-sigma configuration through a double [2+2] cycloaddition.

A study using surface second harmonic generation (SHG) examined molecules at the liquid/vapor interface of water. In particular, this research measured SHG from dimethyl sulfoxide (DMSO) at the liquid/vapor interface of DMSO(aq) solutions at equilibrium and quantified the Gibbs free energy of adsorption of DMSO to the interface. This adsorption-energy value, coupled with data provided in literature, offers a full thermodynamic description of a model potential energy surface for the transport of DMSO across the liquid/vapor interface of water.

It is shown that entropies of desorption can be obtained from temperature programmed desorption (TPD) data. In addition, it is shown that the use of the readily available gas-phase thermodynamic data helps in the determination of the rate constants for surface reactions.