Multi-Photon Spectroscopic Studies of Molecule/Metal Interfaces and Graphene

This dissertation presents multi-photon spectroscopic studies on molecule/metal interfaces and graphene. Two different aspects of these ultrathin molecular or atomic materials were investigated: (1) the electronic structure of molecule/metal interfaces and (2) nonlinear optical properties of graphene. For the case (1), two-photon photoemission (TPPE) using a femotosecond laser was employed to investigate occupied and unoccupied electronic states of molecule/metal interfaces. Here we selected two specific examples of interfaces, benzenethiols on Cu(111) and hexa-cata-hexabenzocoronene (HBC) on Cu(111), which are important model systems for an organic / electrode interface of organic semiconductor devices. Although the same copper substrate was used for all the experiments, the nature of interfaces was strongly affected by the interaction between molecular adlayers and metal substrate. Our TPPE measurements on two benzenthiol species, thiophenol and p-fluorothiophenol, on Cu(111) focus on the role of adsorbates in shifting surface polarization and effecting surface electron confinement. As the coverage of each molecule increases, their photoemission-measured work functions exhibit nearly identical behavior up to 0.4-0.5 ML, at which point their behavior diverges; this behavior can be fit to an interfacial bond model for the surface dipole. In addition, our results show the emergence of an interfacial electronic state 0.1-0.2 eV below the Fermi level. This electronic state is attributed to quantum-mechanical-confinement shifting of the Cu(111) surface state by the molecular adsorbates. Another TPPE study of ours was carried out on an organic semiconductor, HBC, deposited on Cu(111). An increase of HBC coverage continuously shifts the vacuum level of the Cu substrate until a coverage of 2 ML is reached. In the same range of coverage, the Shockley state and the image potential states are quenched while new unoccupied states develop. The momentum- and polarization-resolved photoemission spectra reveal that the new states are originated from a Cu image state. Electron localization is discussed with respect to the structural evolution of HBC. For the case (2), nonlinear optical scanning microscopy was designed to study third-harmonic generation (THG) from micron- scale graphene crystals on glass substrate. The polarization-, thickness-, and orientation- dependence of THG signals from the graphene were measured and compared to theoretical prediction using the nonlinear optical slab model of Bloembergen and Pershan. The results revealed in-plane isotropy and out-of-plane anisotropy of the THG signals and sub-quadratic dependence of the layer number. Due to the strong THG signal, background-free imaging of graphene crystal was carried out. This result implies the potential application of THG for imaging graphene on arbitrary substrates

Cherry Angiomas on the Scalp

Cherry angiomas are a common cutaneous vascular proliferation which manifests as single or multiple spots and occurs predominantly on the upper trunk and arms. They typically appear as round-to-oval, bright, red, dome-shaped papules and pinpoint macules measuring up to several millimeters in diameter. The histopathologic findings of a cherry angioma are consistent with a true capillary hemangioma, which is formed by numerous, newly developed capillaries with narrow lumens and prominent endothelial cells arranged in a lobular fashion in the papillary dermis. Herein, we report a case of multiple cherry angiomas on the scalp, an uncommon location for cherry angiomas

Design and Experimental Validation of a Control System for Dynamic Positioning of a Shuttle Tanker

In this paper, a dynamic positioning performance evaluation procedure for a shuttle tanker is discussed through experimental and numerical analyses. A dynamically positioned shuttle tanker with six thrusters (three tunnel thrusters, two azimuth thrusters, and one main propeller with a rudder), operated in deep water condition was considered. A conventional proportional-derivative control algorithm was adopted for the main feedback control algorithm to reduce the position error, and an anti-windup integral control algorithm was introduced to suppress the steady-state error in the dynamic positioning operation. A minimum power consumption algorithm, based on the Lagrange multiplier method, was utilised in the thrust allocation for the thruster systems. An extended Kalman filter was used in the experiment to separate the low-frequency motion from the measured vessel motion. A set of experiments and numerical analyses were conducted in this study under the same environmental conditions and with the same control methodology. The dynamic positioning operation results obtained by the experiments and numerical simulations were compared to evaluate the station-keeping performance of the dynamically positioned shuttle tanker

Methano­ldinitrato[N-(2-pyridylmethyl­ene)aniline]copper(II)

The Cu atom in the title compound, [Cu(NO3)2(C12H10N2)(CH3OH)], adopts a square-pyramidal geometry, being ligated by two N atoms of the bidentate N-(2-pyridylmethyl­ene)­aniline (ppma) ligand, two O atoms of NO3 ligands and one O atom of a methanol molecule, which occupies the apical position. The phenyl ring on the ppma ligand is twisted out of the pyridine plane, forming a dihedral angle of 42.9 (1)°. In the crystal, inter­molecular O—H⋯O hydrogen bonds between methanol and NO3 ligands form an extensive one-dimensional network extending parallel to [100]