Laser induced copper electroless plating on polyimide with Q-switch Nd:YAG laser

The results of laser induced deposition of copper on polyimide substrate from copper electrolyte solution are reported. Unlike most work reported in the literatures where CW Ar⁺ lasers were used, a second harmonic (532 nm wavelength) Q-switch Nd:YAG laser was used for our experiments. The deposition process was conducted by laser-catalyzing of the polyimide surface and subsequent photothermal-accelerated reduction of copper-complex ions in an alkaline reducing environment. The characteristics of the deposited copper line were investigated in terms of laser beam scanning speed, and the number of scans. The surface morphology and chemical composition of the deposited copper were analyzed using field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDX). The optimum processing conditions have been identified. The copper deposit was found to adhere well to the substrate.     

Quantum chemical modeling for 157 nm photolithography

In its continuing quest for smaller length scales, the electronics industry plans to introduce 157 nm as the next lithographic wavelength. Accordingly, there is a pressing need to develop photoresists that are more transparent, and pellicles that are both more transparent and more durable. With the advent and popularization of time-dependent density functional theory (TD-DFT), we now have a practical quantum chemical method for calculating excitation energies and transition moments in the vacuum ultraviolet (VUV) which can greatly assist in the scouting of highly transparent materials. We have performed TD-DFT calculations for a broad variety of fluorinated molecules and we will report calculated VUV photoabsorption spectra for a large family of model fluorohexanes. These calculations, which span a range from 1-fluorohexane to CH₃CF₂CF₂CF₂CF₂CH₃, illustrate some of the principles one may use to design low absorption polymeric materials.     

Electrocatalytic properties of Au(111)-Pd quasi-single-crystal film electrodes as probed by ATR-SEIRAS

Electrochemical and electrocatalytic properties of thin films Au(111-25 nm), which are quasi-single-crystal electrodes 25 nm thick made of gold with the (111) preferential orientation, and same electrodes modified with a monolayer (ML) of palladium are studied in 0.1 M solutions of HClO₄ and H₂SO₄ employing voltammetric techniques and surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS). Spectroscopic experiments demonstrate strong adsorption of electrolyte species (H₂O, OH_ads, anions) on the Pd surface. The weak and reversible adsorption of CO on Au(111-25 nm) does not change the interfacial-water structure. Adsorption of CO on the Pd-modified film results in an irreversibly adsorbed CO adlayer stabilized by co-adsorbed isolated water species. Various electrooxidation mechanisms are discussed. Electrochemical and spectroscopic investigations on the adsorption and electrooxidation of HCOOH on bare and 1 ML Pd-Au(111-25 nm) electrodes reveal that electrooxidation proceeds in both cases via a direct or dehydrogenation pathway. This mechanism involves the formation of formate as intermediate, which is detected by in situ ATR-SEIRAS. The reactivity on Pd-modified surfaces is higher than on bare gold. The specifically adsorbed anions (sulfate/bisulfate) and the oxide formation on the substrate surface lower the reactivity for CO and HCOOH on both surfaces. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 11, pp. 1312–1329. Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes,” October 18–22, 2005, Moscow. The text was submitted by the authors in English.     

Two-photon Dissociation Study of Carbon Disulfide in Acetonitrile at 266 nm

Using laser flash photolysis/transient absorption technique for the study of two photon photodissociation of carbon disulfide in acetonitrile solution at 266 nm, the transient UV-Vis absorption spectrum of Rydberg state CS2 （6sσg） within 240-370 nm and subsequent dissociation product CS （α^3П） with the maximum absorption at 260 nm were directly observed. The lifetime of CS （α^3П） in the nitrogen and oxygen saturated solution is also studied in our experiment.     

185 nm UV降解水中4-CP、4-NP和Rh B的研究

本文以对氯苯酚(4-CP)、对硝基苯酚(4-NP)和罗丹明B(Rh B)为模型有机物(以4-CP和4-NP为小分子模型有机物,以Rh B为大分子模型有机物),分别研究了185 nm UV对水中这3种模型有机物的降解规律、性能和效果.研究结果表明,185 nm UV直接对水中4-CP、4-NP和Rh B有很好的降解效果.研究内容包括:185 nm UV降解模型有机物的浓度、TOC(Total organic carbon)浓度、185 nm UV降解模型有机物过程中溶液pH及电导率变化、以及降解模型有机物过程中产生的无机离子等几个方面.     

Imaging Photodissociation Dynamics of MgO at 193 nm

In this work, we used time-sliced ion velocity imaging to study the photodissociation dynamics of MgO at \mbox{193 nm}. Three dissociation pathways are found through the speed and angular distributions of magnesium. One pathway is the one-photon excitation of MgO(X\begin{document}$^1\Sigma^+$\end{document}) to MgO(G\begin{document}$^1\Pi$\end{document}) followed by spin-orbit coupling between the G\begin{document}$^1\Pi$\end{document}, 3\begin{document}$^3\Pi$\end{document} and 1\begin{document}$^5\Pi$\end{document} states, and finally dissociated to the Mg(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{u}$\end{document})+O(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{g}$\end{document}) along the 1\begin{document}$^5\Pi$\end{document} surface. The other two pathways are one-photon absorption of MgO(A\begin{document}$^1\Pi$\end{document}) state to MgO(G\begin{document}$^1\Pi$\end{document}) and MgO(4\begin{document}$^1\Pi$\end{document}) state to dissociate into Mg(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{u}$\end{document})+O(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{g}$\end{document}) and Mg(\begin{document}$^1$\end{document}S\begin{document}$_\textrm{g}$\end{document})+O(\begin{document}$^1$\end{document}S\begin{document}$_\textrm{g}$\end{document}), respectively. The anisotropy parameters of the dissociation pathways are related to the lifetime of the vibrational energy levels and the coupling of rotational and vibronic spin-orbit states. The total kinetic energy analysis gives \begin{document}$D_0$\end{document}(Mg\begin{document}$-$\end{document}O)=21645\begin{document}$\pm$\end{document}50 cm\begin{document}$^{-1}$\end{document}.     

Beyond labels: A review of the application of quantum dots as integrated components of assays, bioprobes, and biosensors utilizing optical transduction

A comprehensive review of the development of assays, bioprobes, and biosensors using quantum dots (QDs) as integrated components is presented. In contrast to a QD that is selectively introduced as a label, an integrated QD is one that is present in a system throughout a bioanalysis, and simultaneously has a role in transduction and as a scaffold for biorecognition. Through a diverse array of coatings and bioconjugation strategies, it is possible to use QDs as a scaffold for biorecognition events. The modulation of QD luminescence provides the opportunity for the transduction of these events via fluorescence resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET), charge transfer quenching, and electrochemiluminescence (ECL). An overview of the basic concepts and principles underlying the use of QDs with each of these transduction methods is provided, along with many examples of their application in biological sensing. The latter include: the detection of small molecules using enzyme-linked methods, or using aptamers as affinity probes; the detection of proteins via immunoassays or aptamers; nucleic acid hybridization assays; and assays for protease or nuclease activity. Strategies for multiplexed detection are highlighted among these examples. Although the majority of developments to date have been in vitro, QD-based methods for ex vivo biological sensing are emerging. Some special attention is given to the development of solid-phase assays, which offer certain advantages over their solution-phase counterparts.     

用于氢原子1S-2S光谱研究的超窄线宽243nm半导体激光

近年来,随着激光稳频技术的发展,人们可以把972nm的外腔半导体激光器产生的激光进行放大和四倍频,并将它锁定到超稳定的光学法布里-珀罗腔上,从而可以获得Hz量级超窄线宽的243nm激光,使其成为研究氢原子1S-2S双光子跃迁的有力工具.文章主要介绍了超稳腔、四倍频243nm半导体激光器的研究进展及在氢原子1S-2S双光子跃迁精密光谱研究中的应用.     

Numerical simulation of end-pumped CW Nd^3＋：GdVO4 laser at 1063 nm

A theoretical model to simulate an end-pumped CW Nd^3＋：GdVO4 laser at 1063 nm is presented. Its essence is to use the propagation equations to demonstrate the spatial evolutions of the pump and the laser powers in the cavity, hence it is applicable to both low and high gain lasers. The simulation results obtained by this model are in good agreement with the experimental observations reported in the literature for a Ti：sapphlre-pumped Nd^3＋：GdVO4 laser. Moreover, some parameters, such as the reflectivity of output coupler, the spot size of laser beam and the crystal length, are discussed with a view to optimizing the laser performance.     

Analysis of a separate 1319 and 1338 nm Nd:YAG laser with a blazing grating

We develop a separate 1319 and 1338 nm Nd:YAG laser system with a blazing grating (600 lines/mm). The resonator of this system has a Littrow grating configuration and a highly reflective mirror, in which the zero-order diffraction of the grating acts as the laser output. By virtue of the wavelength-dependent reflectivity of the grating, a single-wavelength laser at 1319 nm or 1338 nm can be realized. In view of the laser rate equations and using the distribution of the blazing grating, we analyze the oscillation conditions providing single-wavelength laser operation in the system.