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The new results for the water dimer equilibrium constant, K(sub p)(T) in the range 190-390 K, using a flexible potential energy surface fitted to spectroscopical data are presented. The newly calculated values for K(sub p)(T) are in very good agreement with available experimental data at room temperature, and at higher temperatures, with the analysis of the convergence of the partition function reveals that quasi-bound states are likely to contribute to the equilibrium constant.

A study to measure the nitrogen K-edge spectra of aqueous proline and diglycine solutions by total electron yield near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at neutral and high pH was performed. The results revealed that the alpha amine group is present in an acceptor-only configuration while the end of butylammonium side chain is fully solved.

A diffraction grating with a large diffraction efficiency has been inscribed on an azobenzene-containing polymer thin film, electrically poled and characterized using spatially resolved Raman confocal microscopy and near-field scanning optical microscopy. Linear and nonlinear polarized microscopic measurements have been performed on a grating.

An investigation of the photophysical characteristics of the liquid-crystalline random copolyester, Vectra A910 is presented. Four phase transitions were observed from an experimental temperature range from -180 to +400 degrees Celsius.

The methods to obtain various mesostructures made of nanocrystals are described. These mesostructures create new physical properties, which differentiate isolated nanocrystals with those of a bulk phase.

Studies are conducted on liquid water microjets by soft X-ray adsorption spectroscopy is presented. The results reveal that an equilibrium liquid water surface dominated by water molecules interacting weakly at longer distances supports the predictions from computer simulations.

A demonstration that highly ordered nanocrystals superlattices can be achieved if stable wetting layer of solvent is maintained on the substrate is presented. It is found that the superlattice structures are robust and the final dewetting of the solvent does not perturb them.

Research is presented illustrating the development of experimental techniques and algorithms for extracting the complex dielectric function of thin films of quantum dots.

The hydrogen-bond acceptor antisymmetric O-D stretch in the (D2O)2 isotopomer was measured and analyzed using infrared (IR) cavity ringdown laser absorption spectroscopy. Analysis of the water dimer shows that, of the three IR modes quantified, the acceptor antisymmetric stretch was the only one that did not quickly predecompose the cluster, suggesting a relatively weak coupling been the vibrational mode and the hydrogen bond.

A simple classical effective medium computation of a two-dimensional monolayer of silver 30 angstrom diameter nanocrystals was developed and compared with experimental results. Results showed that if interparticle separation is more than 10 angstroms, the linear optical response is appropriately described by the classical effective medium model. However, the classical model does not represent the drastic changes in the reflectance spectrum seen around D/2r = 1.2.

Recent developments in chemical techniques for producing narrow size distributions of various metal (1) and semiconductor (2-4) quantum dots, and for fabricating ordered superlattices from these nanocrystals, have sparked much [...], The linear and nonlinear ([Χ.sup.(2)]) optical responses of Langmuir monolayers of organically functionalized silver quantum dots were measured as a continuous function of interparticle separation under near-ambient conditions. As the distance between metal surfaces was decreased from 12 to ~5 angstroms, both quantum and classical effects were observed in the optical signals. When the separation was less than 5 angstroms, the optical second-harmonic generation (SHG) response exhibited a sharp discontinuity, and the linear reflectance and absorbance began to resemble those of a thin metallic film, indicating that an insulator-to-metal transition occurred. This transition was reversible.

Cavity ringdown laser absorption spectroscopy (CRLAS) is a combination of simple commercial pulsed lasers and standard electronics with high-reflectance mirrors. CRLAS can be utilized for measuring trace species concentrations with high sensitivity and good time resolution. The CRLAS approach also features simple design and operation for the analysis of transient molecules in molecular beams, chemical kinetics, flame and plasma diagnostics. Furthermore, high-resolution CRLAS was also developed based on the cavity-attenuated phase shift method.

The theory, development and applications of the cavity ringdown laser absorption spectroscopy (CRLAS), with focus on the application of pulsed molecular beam spectroscopy, are discussed. CRLAS is a newly developed direct absorption technique which measures the electronic spectra of jet-cooled molecules and clusters with both high sensitivity and high spectral resolution. The evaluation of the method characterizes it as a simple, sensitive and powerful tool for spectroscopic studies.

The quest for a genuine molecular description of bulk-phase water has motivated two lines of research. The first entails a convergence of theory and experiment in determining an accurate six-dimensional [...], Measurement of the far-infrared vibration-rotation tunneling spectrum of the perdeuterated water tetramer is described. Precisely determined rotational constants and relative intensity measurements indicate a cyclic quasi-planar minimum energy structure, which is in agreement with recent ab initio calculations. The O-O separation deduced from the data indicates a rapid exponential convergence to the ordered bulk value with increasing cluster size. Observed quantum tunneling splittings are interpreted in terms of hydrogen bond rearrangements connecting two degenerate structures.

One of the most intriguing current problems in astrophysics is to identify the carriers of the visible diffuse interstellar absorption bands (DIBs) (1) and the unidentified infrared emission bands (UIRs) [...], Infrared emission spectra of gas-phase naphthalene and pyrene have been measured in the range of 3 to 7.5 micrometers with ultraviolet laser desorption-excitation and a spectroscopic technique featuring single-photon counting in the infrared. The spectra were compared with the unidentified infrared emission bands that are observed in many astronomical objects. Marked discrepancies between those observations and the laboratory emission spectra in the wavelengths and relative intensities of principal spectral features led to the conclusion that small neutral unsubstituted polycyclic aromatic hydrocarbons cannot be the carriers of the unidentified infrared emission bands.

The structure and bonding in pure carbon molecules have been of interest for many years because of the importance of these species in many contexts, ranging from dust-grain formation in [...], The infrared absorption spectrum of a linear, 13-atom carbon cluster ([C.sub.13]) has been observed by the use of a supersonic cluster beam-diode laser spectrometer. Seventy-six rovibrational transitions were measured near 1809 wave numbers and assigned to an antisymmetric stretching fundamental in the [[sigma.sup.1].sub.g.sup.+] ground state of [C.sub.13]. This definitive structural characterization of a carbon cluster in the intermediate size range between [C.sub.10] and [C.sub.20] is in apparent conflict with theoretical calculations, which predict that clusters of this size should exist as planar monocyclic rings.

Tunable far-infrared laser spectroscopy facilitated the study of internal dynamics of the hydrogen bonding network of the water trimer. Novel intermolecular vibrations were measured at 87.1 and 98.1 per centimeter. Two classes of structural rearrangements were responsible for the observed oblate asymmetric rotor pattern in the spectrum and the splitting of every rovibrational transitions into quartet.

Despite decades of extensive investigation into the properties of water and its chemical behavior [1], there remain important unanswered questions that may have significant impact on many chemical and biological [...], A detailed experimental study of the water trimer is reported. A vibration-rotation-tunneling band of the perdeuterated cluster has been measured near 89.6 wavenumbers by tunable far infrared laser absorption spectroscopy. The data indicate a chiral six-membered ring structure with rapid quantum tunneling occurring between the enantiomers. The observed vibration involves torsional motion of the water subunits about each hydrogen bond axis. It is speculated that larger water clusters would also exhibit transient chirality and that similar effects may be found in liquid water.

Tunable Far-IR Laser Spectroscopy of Jet-Cooled Carbon Clusters: The [v.sub.2] Bending Vibration of [C.sub.3] THE STUDY OF CARBON CLUSTERS BY both theory and experiment has received a great deal of [...]

A report is presented on the inexpensive fabrication of a large three-dimensional and highly oriented porous microrod array of n-type ZnO semiconductor. This semiconductor has a unique designed architecture consisting of perpendicularly oriented single-crystalline hexagonal rods.

The first characterization of the monomer bending vibrations in gaseous water clusters was conducted by using infrared cavity ringdown spectroscopy. Discrete and sequentially blue-shifted bands near 6 microns for n = 2-4 and unresolved broad features for n > 4, supporting both theoretical computations and solid-state spectroscopy results were obtained. These measurements offer a measure of the monomer distortion that accompanies sequential hydrogen bond formation.

Terahertz laser vibration-rotation tunnelling spectra reveals that the stable form of (H2O)6 has a cage-like structure supported by eight hydrogen bonds. The high intermolecular zero-point energies of the hydrogen bonds are important for the low energy structure. Calculations based on the diffusion quantum Monte Carlo technique indicate that the O-O bond has an average distance of 2.85 Angstroms for the cage hexamer and 2.76 Angstroms for the cyclic isomer. The values compare well with that of liquid water at 298 degrees Kelvin and ice at 223 degrees Kelvin respectively.

Neutral polycyclic aromatic hydrocarbons (PAH) of small size may contribute to less than 10% of the emissions in the unidentified infrared bands (UIR) of intersellar sources. In the laboratory, ultraviolet-laser-induced desorption was used to incorporate excited gas phase PAHs in a low-infrared-background cryogenic vacuum chamber. Bands with substantial differences appearing in typical spectral regions combine to generate an apparent continuum in the UIR spectra between 5.5 and 9.5 micrometers. The 3.3 micrometer bands present in the spectra exhibit considerable invariance in frequency among the various PAHs.

The quasiplanar pentagonal structure formed from five doubly hydrogen-bonded water molecules appears to have a special role in chemical and biological systems. Whereas normal ice ([I.sub.h]) consists of regular arrays [...], Far-infrared laser vibration-rotation tunneling spectroscopy was used to measure a intermolecular vibration (81.19198 wave numbers) of the isolated water ([D.sub.2]O) pentamer. Rotational analysis supports the chiral, slightly puckered ring structure predicted by theory. The experimentally deduced interoxygen separations for the water clusters up to the pentamer showed exponential convergence toward the corresponding distance in bulk phase water.

The [C.sup.7] Cluster: Structure and Infrared Frequencies SMALL CARBON CLUSTERS (LESS THAN 12 atoms) have recently attracted the attention of numerous investigators from a wide variety of disciplines. This is [...]

The experimental measurement of the near-edge X-ray absorption fine structure (NEXAFS) spectra of aqueous glycine for all relevant charge states and elemental K-edges is reported. The insights provided by the pH dependence have led to a reassignment of the previously reported nitrogen K-edge spectrum of vapor phase glycine.

Refined results for the equilibrium constant for water dimerization, computed as a function of temperature via fully coupled 6D calculation of the canonical water (sub 2) partition function on VRT (ASP-W) III, the most accurate water dimer potential energy surface available is reported. The dimer concentrations predicted for high humidity conditions may be sufficient to influence several important atmospheric chemical reactions and perhaps for absorption of sunlight.

Examines the millimeter and submillimeter-wave molecular beam spectrum of the perdeuterated ammonia dimer between 50 and 400 GHz using electric-resonance optothermal spectrometer. Internal rotation complicating the spectrum; Tunneling motions that split the rigid molecule energy levels; Transitions for rotation-tunneling states.

Part II. Reports on the fully coupled six-dimensional calculations of the water dimmer vibration-rotation-tunneling (VRT) states with split Wigner pseudospectral (SWPS) approach. Feasible tunneling motions of the water dimmer and how they are manifested in the microwave and VRT spectra; Overview on the SWPS method and improvements applied to water dimmer.

Studies the O-H stretching vibrations of jet-cooled methanol clusters in direct absorption using infrared cavity ringdown laser absorption spectroscopy. Measurement of rovibrational bands; Measurement of both bonded and free O-H stretches for the dimer; Existence of methanol clusters larger than the dimer in cyclic ring configurations.

Arginine is present in the neutral configuration in a supersonic molecular beam. This was confirmed by experimental evidence from a test of the hypothesis that the most stable form of gaseous arginine is actually zwitterionic. Jet-cooled arginine was subjected to spectroscopic study using the novel ultrasensitive direct absorption method of infrared cavity ringdown laser absorption spectroscopy. The guanidine in the side chain in the proposed configuration acts as an intramolecular proton acceptor, while the carboxylic acid serves as the donor.