The Kennicutt-Schmidt law (Schmidt 1959; Kennicutt 1998, hereafter K-S law) is a power law correlation between area averaged star formation rate (ΣSFR) and gas surface density (Σgas). Despite its importance, the physics that underlie this correlation has remained unclear. The power law index, N, is a prime discriminator of the mechanisms that regulate star formation and form the K-S law (e.g. Leroy et al. 2008; Tan 2010). We present a study of the resolved K-S law for 10 nearby disk galaxies using our new CO(1-0) data at 750 and 500 pc resolutions. The CO(1-0) line emission is established as a tracer of the molecular gas column density, and results in a super-linear correlation (N = 1.3 and 1.8). We discuss the cause of the discrepancy between previous studies, and the mechanism of star formation indicated from our new results.

Large-scale Spitzer surveys of the Galactic plane have yielded a new diagnostic for massive young stellar objects (MYSOs) that are actively accreting and driving outflows: extended emission in the IRAC 4.5 μm band, believed to trace shocked molecular gas. Maser studies of these extended 4.5 μm sources (called EGOs, Extended Green Objects, for the common coding of 3-color IRAC images) have been and remain crucial for understanding the nature of EGOs. High detection rates in VLA CH3OH maser surveys provided the first proof that EGOs were indeed MYSOs driving outflows; our recent Nobeyama 45-m survey of northern EGOs shows that the majority are associated with H2O masers. Maser studies of EGOs also provide important constraints for the longstanding goal of a maser evolutionary sequence for MYSOs, particularly in combination with high resolution (sub)mm data. New SMA results show that Class I methanol masers can be excited by both young (hot core) and evolved (ultracompact HII region) sources within the same massive star-forming region.

Do differences among first languages (LI) affect word recognition in reading a second language (L2)? Participants in this study had either Indonesian (an alphabetic language) or Chinese (a logographic language) as an L1 and were learning English (an alphabetic language) as an L2. Under the connectionist rubric, it was predicted that an alphabetic LI would facilitate word recognition in an alphabetic L2, especially if the LI and L2 have similar spelling patterns. Facilitation is relative to a logographic LI. The model also predicted a better recognition for high-frequency words in the L2 relative to low-frequency words. The results of a lexical decision task largely confirmed these hypotheses.

Matrix-assisted pulsed laser evaporation direct-write (MAPLE-DW) is a laser-based method of directly writing mesoscopic patterns of electronic materials. Patterns of composite BaTiO3/SiO2/TiO2 dielectric material were written onto Pt/Au interdigitated-electrode test structures, with precise control over final dielectric properties. Scanning electron microscopy indicates random close-packed structures of BaTiO3 and SiO3 particles, with interstitial spaces partially filled with titania. Depending on the BaTiO3:silica ratio, the dielectric constant ranged from 5 to 55 and followed a 4-component logarithmic rule of mixing. This work demonstrates that the transfer process and the final material properties of MAPLE-DW oxide materials are largely decoupled.

We apply a number of complementary characterization techniques including electron paramagnetic resonance, optical absorption, and photoluminescence spectroscopies to characterize a wide range of different ZnO phosphor powders. We generally observe a good correlation between the 510-nm green emission intensity and the density of paramagnetic isolated oxygen vacancies. In addition, both quantities are found to peak at a free-carrier concentration ne, of about 1.4 × 1018 cm-3. We also find that the green emission intensity can be strongly influenced by free-carrier depletion at the particle surface, especially for small particles and/or low doping. Our data suggest that the green PL in ZnO phosphors is due to the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band.

We are examining dry processes for wafer cleaning and producing patterned thin films of metal oxides. This research focuses on determining the kinetics and mechanism of the reaction between ß-diketones and selected metal oxides. Preliminary experiments indicated that CuO, MgO, PbO and ZnO all react readily with 1,1,1,5,5,5-hexafluoroacetylacetone (hfacH). Thin films of CuO and MgO were fabricated via pulsed laser deposition, characterized by various analytical techniques such as Rutherford Backscattering Spectrometry and Scanning Electron Microscopy, etched using hfacH, and then further characterized. Etching rates for CuO and MgO were measured in order to develop a mechanistic understanding of the reaction.

We have studied selective chemical vapor deposition (CVD) of copper using (hfac)Cu(VTMS). Copper films were deposited selectively onto tungsten (W) and titanium nitride (TiN) in the presence of silicon dioxide (SiO2) surfaces in a warm-wall CVD reactor. Selective deposition was achieved by in-situ passivation of SiO2 surface hydroxyls by exposure to a silylating agent. These agents, such as dichloro-dimethylsilane and hexamethyldisilazane (HMDS), suppressed the nucleation rate of copper on SiO2 compared to metal surfaces. Control over loss of selectivity during CVD was achieved by maintaining the flow of the silylating agent during deposition. The passivation chemistry was studied by FTIR on a model Cab-O-Sil surface which showed that dichlorodimethylsilane and HMDS pre-dosing shielded the hydrogen-bonded surface hydroxyl groups making them inaccessible to the precursor molecule. An understanding of SiO2 surface modification and control over loss of selectivity during CVD is a key for successful selective copper deposition.

The reactions of metal oxides including CuO, ZnO, V2O5, and PbO with 1,1,1,5,5,5-hexaflouro- 2,4-pentanedione (hfacH) were investigated. A hot-wall reactor was used to react hfacH with metal oxide powders to form sufficient quantities of volatile reaction products for characterization by Infrared Spectroscopy (IR), Elemental Analysis (EA), Nuclear Magnetic Resonance (NMR), Mass Spectroscopy (MS), Thermogravimetric Analysis and Differential Thermal Analysis (DTA). PbO, ZnO and CuO powders reacted rapidly at 200 °C to form the corresponding metal β-diketonates and V2O5 reacted to give OV(hfac)2. A differential cold-wall reactor was to used to measure etch rates of CuOx films as a function of temperature and hfacH partial pressure. AES and XPS analysis of the laser ablation deposited CuOx film annealed in an O2 atmosphere revealed that the film was composed of CuO and Cu2O. Etch rates of up to a I l.βm/min at hfacH partial pressure of 1 Torr at 270 °C were obtained. Laser induced etching of the same CuOx film with hfacH showed evidence of copper oxide removal.

Two relaxation techniques are described, both of which use surface temperature modulation as their basis. In these techniques, modulation of laser light intensity results in a modulation of surface reaction rates. The first technique, a diffusive transport relaxation technique, has been developed to study the chemical reactions occurring under the high pressure conditions used in laser-induced chemical vapor deposition. Perturbation of the reaction rate in a high pressure reactor produces transients in the gas phase reactant and product concentrations for the case of gas phase transport-limited deposition. The product species are differentiated from species formed from the reactant during ionization and fragmentation due to the phase-sensitive nature of the detection scheme. The system response is examined theoretically by examining the response of the gas phase reactant and product concentrations to the modulated surface reaction. The second technique is a new technique which has been developed for obtaining detailed information concerning reaction energetics and pathways of elementary surface reactions. This technique also employs a laser to generate a surface temperature modulation. The laser light is incident on a pure metal film which is mounted within an ultra high vacuum chamber. By modulating the laser intensity, the surface chemical reaction rates are modulated. The combined use of surface temperature modulation and appropriate linearization methods allows a quantitative analysis of the overall reaction energetics to be made. and is used here to investigate the surface processes in a thermal laser-induced reaction.