Vibronic interactions in {6} and {18}hetero(A,B)annulenes

The vibronic (vibrational–electronic) interactions and the Jahn–Teller effects in the monoanions and trianions of {6}hetero(B,N), (C,N), and (B,O)annulenes and {18}hetero(B,N), (C,N), and (B,O)annulenes are discussed. All the heteroannulenes have threefold axis of symmetry and the twofold degenerate lowest unoccupied molecular orbital (LUMOs), and the E^′ or E vibrational modes can cause Jahn–Teller distortions in their monoanions and trianions. State vibronic coupling constants of the monoanions and trianions and orbital vibronic coupling constants concerning the LUMOs are calculated for each Jahn–Teller active vibrational mode at the B3LYP/6-31G* level of theory. Vibrational modes near 1500 cm⁻¹ of the {6}hetero(A,B)annulenes and low-frequency modes (<500 cm⁻¹) of the {18}hetero(A,B)annulenes give large coupling constants, and therefore, these modes are essential in the Jahn–Teller distortions and the vibronic interactions. The coupling constants are qualitatively analyzed by looking at the nuclear motions of the Jahn–Teller active modes and the shapes of the LUMOs on the basis of one-electron approximation.     

Simultaneous Measurement of Refractive Index and Thickness by Low Coherence Interferometry Considering Chromatic Dispersion of Index

Low coherence interferometry can provide simultaneous measurement of refractive index n and thickness t of a transparent plate, as reported recently by some research groups. Precise measurement of n and t is impossible unless chromatic dispersion of index is taken into account. We then proposed and demonstrated a unique technique for simultaneous measurement of phase index n_p, group index n_g and thickness t using a special sample holder. This paper describes a novel technique for simultaneous measurement of n_p, n_g and t using an approximate expression of the chromatic dispersion in terms of n_p. The approximate expression of chromatic dispersion does not require use of the special sample holder, and n_p, n_g and t are determined from two measurable quantities with an accuracy of 0.3% or less, for the sample thickness was around 1 mm. In addition, it is possible to shorten the measurement time compared with the above method.     

High‐resolution resist for screen printing: application to direct fabrication of Ag circuit

High‐resolution screen printing was devised. New resist formulation contains a base polymer, which consists of acid‐labile tetrahydropyranyl‐protected carboxylic acid, hydroxyl, and methacrylic functions. As crosslinkers, multifunctional acrylates were employed. Photoacid generators were used for pattern formation. A 10‐µm feature size of resist on a screen plate was obtained on irradiation at 365 nm and followed by development on a stainless steel screen. Post‐exposure curing improved the mechanical characteristics of the resist patterns. A 13‐µm feature size silver circuit was successfully printed on poly(ethylene terephthalate) film without defect. Copyright © 2011 John Wiley & Sons, Ltd.     

Domain wall dynamics driven by spin transfer torque and the spin-orbit field

We have studied current-driven dynamics of domain walls when an in-plane magnetic field is present in perpendicularly magnetized nanowires using an analytical model and micromagnetic simulations. We model an experimentally studied system, ultrathin magnetic nanowires with perpendicular anisotropy, where an effective in-plane magnetic field is developed when current is passed along the nanowire due to the Rashba-like spin-orbit coupling. Using a one-dimensional model of a domain wall together with micromagnetic simulations, we show that the existence of such in-plane magnetic fields can either lower or raise the threshold current needed to cause domain wall motion. In the presence of the in-plane field, the threshold current differs for positive and negative currents for a given wall chirality, and the wall motion becomes sensitive to out-of-plane magnetic fields. We show that large non-adiabatic spin torque can counteract the effect of the in-plane field.     

A study of electron scattering from benzene: excitation of the 1B1u, 3E2g, and 1E1u electronic states

We report results from measurements for differential and integral cross sections of the unresolved (1)B(1u) and (3)E(2g) electronic states and the (1)E(1u) electronic state in benzene. The energy range of this work was 10-200 eV, while the angular range of the differential cross sections was ～3°-130°. To the best of our knowledge there are no other corresponding theoretical or experimental data against which we can compare the present results. A generalized oscillator strength analysis was applied to our 100 and 200 eV differential cross section data, for both the (1)B(1u) and (1)E(1u) states, with optical oscillator strengths being derived in each case. The respective optical oscillator strengths were found to be consistent with many, but not all, of the earlier theoretical and experimental determinations. Finally, we present theoretical integral cross sections for both the (1)B(1u) and (1)E(1u) electronic states, as calculated within the BEf-scaling formalism, and compare them against relevant results from our measurements. From that comparison, an integral cross section for the optically forbidden (3)E(2g) state is also derived.     

In-situ Observation of Tissue Laser Ablation Using Optical Coherence Tomography

In laser ablation of biological tissue, tomography of the tissue surface is necessary for measurement of the crater shape and the crater depth. In this paper, we demonstrate in-situ observation of biological-tissue surface in laser ablation by optical coherence tomography (OCT). Depth of a crater of human tooth is measured by these OCT images, and then the ablation rate of 0.21 μm/pulse is determined.     

Deposition and characterization of carbon nitride films from hexamethylenetetramine/N2 by microwave plasma-enhanced chemical vapor deposition

Carbon nitride thin films were deposited on Si(1 0 0) substrate by microwave plasma-enhanced chemical vapor deposition (PECVD). Hexamethylenetetramine (HMTA) was used as carbon and nitrogen source while N₂ gas was used as both nitrogen source and carrier gas. The sp³-bonded C---N structure in HMTA was considered significantly in the precursor selection. X-ray diffraction analysis indicated that the film was a mixture of crystalline - and β-C₃N₄ as well as graphitic-C₃N₄ and β-Si₃N₄ which were not easily distinguished. Raman spectroscopy also suggested the existence of - and β-C₃N₄ in the films. X-ray photoelectron spectroscopy study indicated the presence of sp²- and sp³-bonded C---N structures in the films while sp³C---N bonding structure predominated to the sp² C---N bonding structure in the bulk composition of the films. N was also found to be bound to Si atoms in the films. The product was, therefore, described as CN_x:Si, where x depends on the film depth, with some evidences of crystalline C₃N₄ formation.     

Spectroscopic Applications of Integrated Tunable Solid-State Dye Laser

A novel type of tunable laser is developed that integrates dye-doped plastics laser waveguides with a distributed feedback structure. The waveguide matrix is dye doped poly-hydroxyethylmethacrylate:methylmethacrylate, and a single-mode waveguide is achieved by refractive index control. The wavelength coverage is over 560-1100 nm using a frequency doubled Nd:YAG microchip laser. The miniaturizing of the optical-pumped solid-state dye laser extended the lifetime to more than million shots and decreased the required laser threshold energy to less than 1 $mUJ. Novel type spectroscopic applications using the multiple wavelength laser array chip are also proposed and demonstrated.