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The density functional approach was used to systematically investigate the behaviors of the bimetal Mo-Mo doped cagelike silicon clusters [Mo.sub.2][Si.sub.n] at the size of n = 9-16. The results have shown that the dominant growth patterns of the bimetal Mo-Mo doped on opened cagelike silicon clusters (n = 9-13) are based on pentagon prism Mo[Si.sub.10] and hexagonal prism Mo[Si.sub.12] clusters, while the [Mo.sub.2] encapsulated [Si.sub.n] (n = 14-16) frames are dominant growth behaviors for the large-sized clusters.

Static absorption and fluorescence spectroscopy and ultrafast transient absorption measurements are used to investigate the contrasting photophysical properties of two silicon (IV) tetraphenylporphyrins (Si(Tpp)[(py).sub.2] and Si(Tpp)[Cl.sub.2]). The results have shown that the connection between structural distortions and the presence of low-energy excited states have given rise to ultrafast nonradiative deactivation of the photoexcited molecule to the ground electronic state.

The density functional theory (DFT) ab initio calculation of Fe-silicon hybrid redox potentials is reported. It is suggested that the hydrosilylation activated by visible light proceeds through a mechanism, which is not yet described, thus indicating that saturations are preserved during the addition.

The synthesis, characterization, and growth rates of aluminum- and germanium,aluminum-substituted silicalite-1 (Al-silicalite-1, Ge,Al-silicalite-1) materials grown from clear solutions are presented. The results have provided insights about how one can design silicalite-1 nanoparticles with sufficient heteroatom content to be drelevant for catalysis.

The covalent modification of Si surfaces through a two-step chlorination-methylation method is described to introduce kinetically stable C[H.sub.3]-Si bonds onto Si(111) surfaces. The results have provided strong evidence that the energetics of chemically modified Si interfaces can be fixed with respect to pH and have shown that the band-edge energies of Si can be tuned independently of pH-derived variations in the electrochemical potential of the solution redox species.

Ab initio based configuration interaction calculations are conducted to explore the low-lying electronic states and spectroscopic properties of the heaviest nonradioacitve silicon chalcogenide molecule and its monopositive ion. The calculated dissociated energies of SiTe and [SiTe.sup.} are 4.41 and 3.52 eV, respectively and the spin-orbit splitting between the two components of the ground state of [SiTe.sup.} is found to be 1880 [cm.sup.-1].

Conventional and molecular beam Fourier transform microwave spectroscopy is used to measure the rotational spectra of the main isotopomer of the [.sup.29.Si] and of all [.sup.13.C] isotopologues of axial and equatorial forms of 1-fluoro-silacyclohexane. The rotational spectra of some, the most intense, vibrational satellites are measured and they are found to belong to the ring-puckering motions.

A study of the mechanisms of the reaction of H2XN (X = C, Si) is conducted with NO at the level CCSD(T)/aug-cc-PVTZ/B3LYP/6-31++G(d,p). The results indicate that there are two favorable reaction pathways in the reaction H2CN + NO that have similar energy barriers.

The isotropic hyperfine coupling constants of silicon radical defects are calculated using density functional theory. It was found that changes in radical hybridization alongwith changes in first-nearest-neighbor composition are the main factors, which affects the calculated hyperfines.

Threshold photoelectron-photoion coincidence spectroscopy (TPEPICO) is used to study the dissociation kinetics and thermochemistry of [Me.sub.4]Si, [Me.sub.6][Si.sub.2] and [Me.sub.3]SiX, (X = Br, I) molecules. The accurate dissociative photoionization onsets for these species are measured from the breakdown diagram and the ion time-of-flight distribution.

Chemical etching and fluoroalkysilane self-assembly are used as the means to fabricate highly antireflective porous silicon surfaces with superhydrophobicity. The morphology had enabled the porous silicon surface to own a very low reflectance value that is averaged to be about 3% over the whole experimental photon wavelength spanning 300-800 nm.

The binding energies and the corresponding structures of a methane molecule on the silanol covered 010 surface of silicate-I was investigated using ab inito methods. The results showed that the methane molecule will relatively seldom be absorbed on the silanol covered 010 surface of silicate-1, instead the adsorption process will take place directly at the center of the straight channel.

The geometry, chemical bonding and the electronic excitations of [Si.sub.n] and [Si.sub.n]-glycine (Gly) (n = 3-5) complexes are calculated as a potential model of an inorganic cluster-biomolecule system, focusing on the effects of the [Si.sub.n]-Gly interactions on the structures of Gly and on the electronic transitions of [Si.sub.n]. The interactions with Gly are predicted to shift the electronic excitation energies of [Si.sub.n] to the blue from to 2.1-2.7 eV.

The adsorption of substitutionally doped fullerenes [C.sub.59]Si onto a monohydride Si(100) surface is studied. The results are based on ab initio total energy density functional theory and the obtained binding energy is in the order of 2.1 eV.

Density functional cluster model calculations are performed to explore the mechanism and regioselectivity for the reactions of propylene oxide with X(100)-2x1 surfaces (X = C, Si, Ge). It is demonstrated that the reactions of propylene oxide with X(100)-2x1 surfaces (X = C, Si, Ge) are barrierless and highly exothermic, whereas the reaction of propylene oxide with the C(100)-2x1 surface could be kinetically prohibited at room temperature.

Theoretical study of the structures of neutral and singly charged Si(sub n)Li(sub p)(super +) (n = 1-6, p = 1-2) clusters is carried out in the framework of the density functional theory (DFT) with the B3LYP functional. Vertical and adiabatic ionization potentials, adsorption energies, as well as electric dipole moments and static dipolar polarizabilities, are calculated for each isomer of neutral species.

The surface structure, strain energy, and charge profile of the methoxylated Si(111) surface, Si(111)-OCH(sub 3), was studied using quantum mechanics, and the results are compared to those obtained for Si(111)-CH(sub 3) and Si(111)-C(sub 2)H(sub 2). The calculation indicate that 100 percent coverage is feasible for Si(111)-OCH(sub 3) (similar to the methylated surface), as compared to only ~80 percent coverage for ethylated surface.

The kinetics of reaction between silicon nanoparticles and molecular oxygen are studied by tandem differential mobility analysis. These results are useful to semiconductor applications, which needs high quality thin film by thermal oxidation.

The anodic dissolution of silicon in acid solutions of ammonium fluoride was investigated in aqueous and water-alcohol media using a rotating disk voltammetry and impedance spectroscopy. The important differences and similarities shown by investigations in aqueous and water-alcohol media are provided.

The electronic excited states of the Si(100) surface and acetylene, 9,10-phenanthrenequinone and benzene adsorbed on Si(100) is studied with time-dependent density functional theory. The results show that on clean Si(100), the low-lying excitation corresponds to transitions between the pi orbitals of the silicon-silicon dimers.

The polymeric layers covalently anchored to the silicon surface when anodic decomposition of a phenylmagnesium halide takes places at a surface-hydrogenated silicon electrode were characterized using spectroelliposometry, photoluminescence, infrared, and X-ray photoelectron spectroscopy. The phenyl ring appears preserved in the process, and the polymer formed is a polyphenylene.

Ex-situ infrared spectroscopic ellipsometry is used to inspect the Si surface species before and after the electrochemical grafting process of the phenyl layers. It is observed that the use of a suitable concentration and cathodic potential can reduce the influence of side reactions on the process.

A kinetic model for the formation of organic monolayers based on a previously suggested free radical chain mechanism for the reaction of unsaturated molecules with hydrogen-terminated silicon surfaces was analyzed. A direct consequence of this mechanism is the nonexponential growth of the monolayer and it determines the rate at which the monolayer forms by addition of alkene molecules to form a track of molecules that constitute a self-avoiding random walk on the surface.

Temperature-programmed desorption (TPD) was used to study the absorption and reaction of CH(sub 3)SH and (CH(sub 3))(sub 2)S(sub 2) on the (0001) and (0001) surfaces of ZnO. The result indicates that exposed cation-anion site pairs are required for dissociative absorption of (CH(sub3))(sub 2)S(sub 2), but only exposed Zn cations are required for dissociative absorption of (CH(sub 3))(sub 2)S(sub 2).

Sorption of n-hexane on monodimensional pure silica SSZ-35, CIT-5, ZSM-12 and ZSM-22 zeolites with different pore dimension and on the synthesized ITQ-29 was studied. The theoretical calculations clearly showed the accordance between the orientations of sorbed molecules, which are varied for different zeolites and the heat of sorption of hexane.

The effects of wafer miscut and water defects on the morphologies of Si (111) surface etched in NH(sub 4)F are studied by implementing a kinetic Monte Carlo (KMC) simulation. The defects result in persistent pit initiation, which leads to the formation of multilevel stacked pits.

1-Napthol is used to characterize the dispersibility of carbon nanofibres (CNFs) into the sol-gel matrix of silicon alkoxide. This shows that 1-napthol easily interacts with oxidized groups present on the CNF surface, useful for preventing self-assembly or aggregation of the CNFs in the gel matrix, due its high dispersibility.

A joint IR and computational work has allowed a detailed characterization of the isolated silanols at the surface of highly ordered benzene-silica hybrid material and a similar characterization was presented for a less ordered sample. The result reveals that the molecules with simultaneous H-acceptor and H-donor properties might interact with both the acidic proton and in silanols and the electronic cloud in the framework aromatic rings.

A systematic study of the etching behavior, in terms of three-dimensional profiles, of one-dimensional (1-D) silicon nanowires (SiNWs) in NH4F-buffered hydrofluoric acid (BHF) solutions of varying concentrations and pH values is conducted. The results revealed that the SiNWs are stable only in relatively narrow pH ranges of the NH4F-BHF solutions.

A new version of functional stamp materials with adjustable physical toughness was developed for advanced soft lithography. As a result the photopatternable silicon elastomers with enhanced mechanical properties for high-fidelity nanoresolution soft lithography were demonstrated.

The investigation was conducted on the interaction of pyridine with isolated reactive sites on partially H-terminated Si(100), to restrict adsorption to the dative bonded form, while dative bonding on isolated clean dimers was observed, single dangling bonds remain unreacted. The results suggest that a single clean Si dimer is the smallest unit required for this process to proceed and it was predicted that phosphine would not react with isolated Si dangling bonds.

The interactions of cyanoacetylene and diacetylene with a Si(111)-7 x 7 surface is studied as model systems to mechanically understand the chemical binding of unsaturated organic molecules to diradical-like silicon dangling bonds. Results show that cyanoacetylene mainly binds to the surface through a diradical reaction involving both cyano and C(triple bond)C groups.

The study of CO oxidation catalyzed by Au supported on acidic mesoporous silicates is reported. It is found that a high-temperature reduction of the catalyst is crucial for good activity in the catalysis of CO oxidation.

The evaporation of water microdroplets from solid surfaces was studied using digital contact angle analysis techniques. An inclusive mode switching behavior was observed for all surfaces examined, including mixed self-assembled monolayers (SAMs) on gold and 'conventional' surfaces such as silicon wafers, polycarbonate, and Teflon.

Ruppert's reagent, CF3SiMe3 is investigated by gas phase electron diffraction, microwave spectroscopy and quantum chemical methods, deriving structural parameters and the barrier height for the methyl torsion. The bond length of the Si-CF3 bond, 1.941(3) Angstrom, is the longest Si-C bond observed so far in the gas phase.

The molecular configuration of water adsorbed on a hydrophilic silicon oxide surface at room temperature is determined as a function of relative humidity, using attenuated total reflection (ATR)-infrared spectroscopy. It is observed that the outermost layer of the adsorbed water molecules undergoes transitions in equilibrium behavior as humidity varies.

Aligned coaxial nanocables were grown on Si substrates by a vapor-deposition technique where the lengths of nanocables increased as the distance between the substrate and the source decreased. The unique growth manner provides a new technique for the homogenous crystallization of Zn-Zn2SiO4 core-shell nanocables.

The structures, energetic, spectroscopies, and isomerization of various doublet Si2CP species are explored theoretically. Implications in interstellar space and P-doped SiC vaporization processes are discussed.

A density functional theory investigation on a series of S-shaped or cyclic (B(sub n)E(sub m)Si)2H2 molecules (E = B, C, Si; n = 3-6; m = 1, 2) containing double planar tetra-, penta-, and hexacoordinate silicons is presented. Theoretical evidence is provided to support the earlier proposed structural pattern to host planar hypercoordinate silicons in small aromatic molecules.

The detailed investigation of the electrophilic and nucleophilic character of singlet silylenes and germylenes, divalent compounds of silicon and germanium, respectively, substituted by first-and second-row elements is presented. The study demonstrated that an increasing stability of the silylenes and germylenes is accompanied by an increase in their nucleophilicity and a decrease of the electrophilicity.

Two chemisorptions configurations for BRL on Si(100) appear to be both energetically and kinetically favored and these structures are characterized by the formation of four Si-C bonds and are energetically favored at all the surface coverages investigated. The several possible reaction pathways, leading from one stable structure to another of lower energy or from a molecule in the gas phase to a chemisorbed configuration are investigated and estimates of the relative energy barriers are given.

The study carried out reports a facile route for preparing green light emitting Zn(sub 2)SiO(sub 4):Mn phosphor through a low-temperature solid-state reaction method by using mesoporous silica SBA-15 as an active template. The results strongly suggest that the route exhibits a significant advance in facilitating homogeneous doping, enhancing the luminescent properties of the Zn(sub 2)SiO(sub 4):Mn phosphor and lowering the firing temperature.

A three-parameter local hot spot model of gas-surface reactivity was employed to analyze and predict dissociative sticking coefficients for SiH(sub 4) incident on Si(100) under varied nonequilibrium conditions. The threshold energy for SiH(sub 4) dissociative chemisorption is found to be 19kJ/mol, in quantitative agreement with recent GGA-DFT calculations.

The CH3-terminated Si(111) surfaces are imaged that were prepared through a chlorination/alkylation procedure using a low-temperature scanning tunneling microscopy (STM). The predominant interaction determines the surface structure arises from repulsions between hydrogen atoms on neighboring methyl groups, and secondary interactions unique to the surface are also evident.

The molecular structures, electron affinities, and dissociation energies of the Si(sub 3)H(sub n)/Si(sub 3)H(sub 3)(super -) [n(less than or equal to 8)] species using five hybrid and pure density functional theory (DFT) methods is examined. In the prediction of bond lengths, the BHLYP predicts the most reliable Si-Si bond lengths and the B3LYP predicts the most reliable Si-H bond lengths.

The terahertz time-domain spectroscopy (THz-TDS) study of hydrophobic and hydrophilic silica aerogels, and the adsorption of several molecular vapors in the hydrophilic silica aerogel are reported. It was found that the hydrophobic and hydrophilic samples have similar but discernible indices of refraction in the frequency range of 0.2-3.0 THz.

A new series of stilbene-based chromophores were used to prepare structurally related siloxane-based monolayers in order to determine the factors controlling the intermolecular chromophore-chromophore interactions in the solid state. The covalently bound monolayers exhibited a relatively high concentration of surface-bound chromophores, which were restricted in their orientation freedom.

The preparation of alpha-SiAION:Eu-based yellow oxynitride phosphors is described. The effects of the activator concentration and the overall composition of the host lattice on optical properties are investigated.

A new method to obtain silica aerogel particles is proposed using acetic acid as the condensation agent for silicon alkoxides in supercritical carbon dioxide (scCO2). The mechanism of silica aerogel formation in scCO2 using in situ analysis techniques is determined.

Router to Si nanowires with different sizes having erbium-rich shell structures was developed. Further it is found that facile routes for the formation of single-crystal Si naowires coated with polycrystalline Er-rich Si surfaces, with the precise width strongly dictated by selecion of catalyst and associated conditions.