Analysis of the pure-rotational spectrum in the ν28 = 1 excited torsional state and torsional couplings of trans-ethyl methyl ether

The trans-ethyl methyl ether molecule has three low-lying torsional modes, that is, two inequivalent methyl internal rotations and an asymmetric skeletal torsion. The internal rotations of the CCH₃ and OCH₃ methyl rotors and the skeletal torsion correspond to the vibrational modes, ν₂₈, ν₂₉ and ν₃₀ respectively. In this study, the microwave absorption spectrum in the ν₂₈ = 1 CCH₃ torsional state was analyzed for the first time. Nine hundred fifty seven lines up to J = 48 and K = 4 were assigned, and the rotational, centrifugal distortion and internal rotational tunneling parameters were determined with the use of a tunneling matrix formalism. By combining the present results on the ν₂₈ = 1 torsional state with those for the ν₃₀ = 1 skeletal torsional state and the ν₂₉ = 1 OCH₃ torsional state, torsional couplings are estimated in order to understand quantitatively the inverted A/E sequence patterns observed for those three excited torsional states.     

Enhanced effective mass in doped SrTiO3 and related perovskites

The effective mass is one of the main factors determining the Seebeck coefficient and electrical conductivity of thermo-electrics. In this ab-initio LDA-GGA study the effective mass is estimated from the curvature of electronic bands by one-band-approximation and is in excellent agreement with experimental data of Nb- and La-doped SrTiO₃. It is clarified that the deformation of SrTiO₃ crystals has a significant influence on the bandgap, effective electronic DOS-mass and band-mass, but the electronic effect due to the e_g-band flattening near the Γ-point due to Nb-doping up to 0.2 at% is the main factor for the effective mass increase. Doping of La shows a linear decrease of the effective mass; this can be explained by the different surroundings of A- and B-sites in perovskite. Substitution with other elements such as Ba on the A-site and V on the B-site in SrTiO₃ increases the effective mass as well.     

Low temperature deposited Zr-B film applicable to extremely thin barrier for copper interconnect

We have prepared thin Zr-B films at low temperatures as a new material applicable to an extremely thin barrier against Cu diffusion in Si-ULSI metallization. The obtained Zr-B films mainly consist of the ZrB₂ phase with a nanocrystalline texture on SiO₂ and a fiber texture on Cu. The resistivity of the Zr-B films depends on the substrate of SiO₂ or Cu. The constituent ratio of B/Zr is almost 2, though the contaminants of oxygen, nitrogen, and carbon are incorporated in the film. The nanocrystalline structure of the Zr-B film on SiO₂ is stable due to annealing at temperatures up to 500 °C for 30 min. We applied the 3-nm thick Zr-B film to a diffusion barrier between Cu and SiO₂, and the stable barrier properties were confirmed. We can demonstrate that the thin Zr-B film is a promising candidate for thin film application to a metallization material in Si-ULSIs.     

Porous silicon-based ferroelectric nanostructures

A procedure is suggested for the preparation of porous silicon-based ferroelectric nanostructures. It is demonstrated that the method of chemical deposition from solutions provides for the penetration of the initial components of the solution into the matrix pores, and subsequent annealing leads to the crystallization of the ferroelectric phase. The diagnostics of the ferroelectric properties is performed using the method of generation of second optical harmonic. The spectral characteristics of the prepared ferroelectric nanostructures are investigated.     

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

It was shown both theoretically and experimentally that nanosecond order laser pulses at 10.6 micron wavelength were superior for driving the Sn plasma extreme ultraviolet (EUV) source for nano-lithography for the reasons of higher conversion efficiency, lower production of debris and higher average power levels obtainable in CO₂ media without serious problems of beam distortions and nonlinear effects occurring in competing solid-state lasers at high intensities. The renewed interest in such pulse format, wavelength, repetition rates in excess of 50 kHz and average power levels in excess of 18 kiloWatt has sparked new opportunities for a matured multi-kiloWatt CO₂ laser technology. The power demand of EUV source could be only satisfied by a Master-Oscillator-Power-Amplifier system configuration, leading to a development of a new type of hybrid pulsed CO₂ laser employing a whole spectrum of CO₂ technology, such as fast flow systems and diffusion-cooled planar waveguide lasers, and relatively recent quantum cascade lasers. In this paper we review briefly the history of relevant pulsed CO₂ laser technology and the requirements for multi-kiloWatt CO₂ laser, intended for the laser-produced plasma EUV source, and present our recent advances, such as novel solid-state seeded master oscillator and efficient multi-pass amplifiers built on planar waveguide CO₂ lasers.     

Reinterpretation of the molecular O2 chemisorbate in the initial oxidation of the si(111)7 x 7 surface

The initial oxygen adsorption on the Si(111)7 x 7 surface was investigated by high-resolution x-ray absorption spectroscopy. Below 220 K, a molecular adsorption species is identified by distinctive absorption resonances due to the 1 pi(g) molecular orbitals. The molecular species is metastabilized to have a lifetime of 15-35 min at 135 K only with the presence of atomic adsorbates of more than 0. 1 ML (monolayer). It is thus clearly evidenced that the very initial adsorption is dissociative even at 100 K and the molecular species is not a precursor state. The molecular adsorption structures with the coadsorbed oxygen atoms are suggested.     

Propagation of the state change induced by external forces inlocal interactions

This paper analyses the propagation of the state changes of agents that are induced byexternal forces applied to a plane. In addition, we propose two models for the behavior ofthe agents placed on a lattice plane, both of which are affected by local interactions. Wefirst assume that agents are allowed to move to another site to maximise theirsatisfaction. Second, we utilise a model in which the agents choose activities on eachsite. The results show that the migration (activity) patterns of agents in both modelsachieve stability without any external forces. However, when we apply an impulsiveexternal force to the state of the agents, we then observe the propagation of the changesin the agents’ states. Using simulation studies, we show the conditions for thepropagation of the state changes of the agents. We also show the propagation of the statechanges of the agents allocated in scale-free networks and discuss the estimation of theagents’ decisions in real state changes. Finally, we discuss the estimation of the agents’decisions in real state temporal changes using economic and social data from Japan and theUnited States.