Comparison of two confocal micro‐XRF spectrometers with different design aspects

Two different confocal micro X‐ray fluorescence spectrometers have been developed and installed at Osaka City University and the Vienna University of Technology Atominstitut. The Osaka City University system is a high resolution spectrometer operating in air. The Vienna University of Technology Atominstitut spectrometer has a lower spatial resolution but is optimized for light element detection and operates under vacuum condition. The performance of both spectrometers was compared. In order to characterize the spatial resolution, a set of nine specially prepared single element thin film reference samples (500 nm in thickness, Al, Ti, Cr, Fe Ni, Cu, Zr, Mo, and Au) was used. Lower limits of detection were determined using the National Institute of Standards and Technology standard reference material glass standard 1412. A paint layer sample (cultural heritage application) and paint on automotive steel samples were analyzed with both instruments. The depth profile information was acquired by scanning the sample perpendicular to the surface. © 2013 The Authors. X‐Ray Spectrometry published by John Wiley & Sons, Ltd.     

Diradical Character Tuning for the Third‐Order Nonlinear Optical Properties of Quinoidal Oligothiophenes by Introducing Thiophene‐S,S‐dioxide Rings

To create a design guideline for efficient third‐order nonlinear optical (NLO) molecules, the chain‐length (n) dependences of the diradical character y and the longitudinal second hyperpolarizability γ of quinoidal oligothiophenes (QTs), from monomers to octamers, involving thiophene‐S,S‐dioxide rings are investigated by using the density functional theory method. It turns out that the diradical character of the modified QTs is reduced as compared to those of the pristine QTs. By introducing an appropriate number of oxidized rings into the QT framework, intermediate y values can be achieved even in the systems with large values of n, in which the pristine QTs are predicted to have pure diradical character. Such intermediate diradical oligomers are shown to exhibit enhanced γ values as compared to the pristine QTs with the same value for n. From the calculation results, the introduction of the optimal number of thiophene‐S,S‐dioxide rings is predicted to be an efficient chemical modification for optimizing the third‐order NLO properties of open‐shell QTs through tuning the diradical characters.     

Theoretical Study on the Relationship between Diradical Character and Second Hyperpolarizabilities of Four‐Membered‐Ring Diradicals Involving Heavy Main‐Group Elements

By using spin‐unrestricted density functional theory methods, the relationship between the diradical character y and the second hyperpolarizability γ (the third‐order nonlinear optical (NLO) properties at the molecular scale) for four‐membered‐ring diradical compounds, that is, cyclobutane‐1,3‐diyl, Niecke‐type diradicals, and Bertrand‐type diradicals, were investigated by focusing on the substitution effects of heavy main‐group elements as well as of donor/acceptor groups on the y and γ values. It has been found that i) γ is enhanced in the intermediate y region for these four‐membered‐ring diradicals, ii) Niecke‐type diradicals with intermediate y values, which are realized by tuning the combination of the main‐group elements involved, exhibit larger γ values than Bertrand‐type diradicals, and iii) the y value and thus γ value can be controlled by modifying the both‐end donor/acceptor substituents attached to carbon atoms in Nicke‐type C₂P₂ diradicals. These results demonstrate that four‐membered‐ring diradicals involving heavy main‐group elements exhibit high controllability of the y and γ, which indicates the potential applications of four‐membered‐ring diradicals as a building block of highly efficient open‐shell NLO materials.     

Muonic X-ray measurements on mixtures of CaO/MgO and Fe3O4/MnO

Journal of Radioanalytical and Nuclear Chemistry - Elemental analysis by measurement of muonic X-rays shows great potential for analyzing the elemental composition of a bulk material at a specific...     

Muscle‘s Motion in an Overdamped Regime

Based on the stochastic inclined rods model proposed by H.Matsuura et al., we study the motion of actin myosin system in an overdamped regime.Our model is composed of an inclined spring (rod),a myosin head and a myosin filament.The results of calculation show that the model can convert the random motion to one-directional motion,and the myosin head works as a resonator of random noise,which absorbs the energy through a stochastic resonance.The results show that the inclined rod and the intermolecular potential are very important for the system to move.     

Electric-field dependent electron mobility in anthracene single crystals

We observed the electric-field dependence of electron drift velocity in the c′ direction of anthracene single crystals at low temperature and found out that it tends to almost constant value above the electric-field of 1.8 × 10⁵ V cm^-1 at 140 K deviating from the linear proportionality to the field below this value. This result may be regarded as an experimental verification for the recent theoretical prediction by Sumi.     

Theoretical Analysis of Photon-Mode Super-Resolution Optical Memory Using Saturable Absorption Dye

The possibility of a super-resolution optical memory using a saturable absorption dye mask layer is theoretically discussed. An equation which estimates the transmittance change of the mask layer has been derived. The numerical simulation shows that an efficient super-resolution is performed when the initial optical density of the mask layer is high.