Erbium-doped lead silicate glass for near-infrared emission and temperature-dependent up-conversion applications

Erbium-doped lead silicate glass has been investigated for near-infrared emission and up-conversion applications. Near-infrared emission due to ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ is relatively broad (70.5 nm) and long-lived (3.7 ms). Also, up-conversion luminescence spectra of Er³⁺ ions in lead silicate glass have been examined as a function of temperature. The relative intensities of luminescence bands corresponding to ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 transitions of Er³⁺ were determined with temperature. The fluorescence intensity ratio and temperature sensitivity were calculated. The maximum sensitivity for Er³⁺ doped lead silicate glass is close to 26.4 × 10^?4 K^?1 at T = 590 K.     

Using photoelectron emission microscopy with hard-X-rays

We present several successful test cases of using photoelectron emission microscopy (PEEM) for photon energy up to 25 keV. First, the full extended X-ray absorption fine structure analysis was implemented in areas as small as 100 μm² for transition-metal K edge absorption spectra and, therefore, demonstrated the feasibility of combining structural and chemical analysis with hard-X-ray absorption spectroscopy with high lateral resolution. We also show that PEEM can be used in a transmission (radiography) mode as an imaging detector for hard-X-ray. This approach again leads to the unprecedented 0.3 μm lateral resolution, particularly critical for the use of coherence-based phase contrast techniques in real time X-ray radiology.     

Luminescence of Cs2PtF6

In the past five years, a number of d⁶ complexes have been found to exhibit luminescence when excited by ultraviolet light. Such emission has been assigned to d-d transitions localized on the metal ion, to charge-transfer transitions, and to ligand localized transitions^2,3. The specific kind of emission observed is thought to depend on which electronic level lies lowest in energy.     

Microplasma Technology and Its Applications in Analytical Chemistry

Abstract

This review article describes some existing microplasma sources and their applications in analytical chemistry. These microplasmas mainly include direct current glow discharge (DC), microhollow-cathode discharge (MHCD) or microstructure electrode (MSE), dielectric barrier discharge (DBD), capacitively coupled microplasmas (CCμPs), miniature inductively coupled plasmas (mICPs), and microwave-induced plasmas (MIPs). The historical development and recent advances in these microplasma techniques are presented. Fundamental properties of the microplasmas, the unique features of the reduced size and volume, as well as the advantageous device structures for chemical analysis are discussed in detail, with the emphasis toward detection of gaseous samples. The analytical figures of merit obtained using these microplasmas as molecular/elemental-selective detectors for emission spectrometry and as ionization sources for mass spectrometry are also given in this review article.     

Conditional Probabilities and Density Operators in Quantum Modeling

Motivated by a recent proof of free choices in linking equations to the experiments they describe, I clarify some relations among purely mathematical entities featured in quantum mechanics (probabilities, density operators, partial traces, and operator-valued measures), thereby allowing applications of these entities to the modeling of a wider variety of physical situations. I relate conditional probabilities associated with projection-valued measures to conditional density operators identical, in some cases but not in others, to the usual reduced density operators. While a fatal obstacle precludes associating conditional density operators with general non-projective measures, tensor products of general positive operator-valued measures (POVMs) are associated with conditional density operators. This association together with the free choice of probe particles allows a postulate of state reductions to be replaced by a theorem. An application shows an equivalence between one form of quantum key distribution and another with respect to certain eavesdropping attacks.     

Interferometric monitoring of single-mode operation of a tunable injection laser

We propose a technique for rapid monitoring of single-mode operation of a tunable injection laser, based on analysis of the fine structure of the power-current characteristic obtained with self-heterodyning, using a Michelson interferometer. The technique makes it possible to determine the range for single-mode lasing and mode tuning as well as the presence of spurious optical feedback, and to estimate the coherence length. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 119–123, January–February, 2006.     

An application of the dust grain charging model to determination of secondary electron spectra

Dust grains – objects of different shapes with a size distribution from micro to nanometers – are generally considered as a part of many space as well as laboratory plasmas. Among various dust charging processes, electron-induced secondary emission plays an important role in plasmas containing a noteworthy portion of high-energy electrons. Since a part of secondary electrons has not the energy high enough to overcome the surface potential barrier, the resulting grain charge is determined not only by the secondary emission yield (related to the grain material and size) but also by the secondary electron spectrum. We have developed a model of secondary electron emission from small dust grains. In the present contribution, we discuss the profile of a secondary emission yield that can be received from the model and the measured equilibrium grain charge, both as functions of an incident electron beam energy. A comparison of these quantities leads to an estimation of secondary electron spectra. We have found that: (1) the energy spectrum of secondary electrons does not change with the energy of primary electrons and (2) the energy spectrum depends on the target material being harder for gold and silver than for glass grains.     

Underwater Directional Acoustic Source Based on Pentamode Material

An underwater directional acoustic emitter is conceived with a highly anisotropic lattice material,whose acoustic charac-teristics manifest strong dependence on the orientation of the lattice material's principal axis.Exploiting these features,a cylindrical structure made of such anisotropic lattice material is engineered to possess distinct impedance values in different directions,thereby facilitating wave emission along the principal axis while inducing reflection in other directions.Notably,through numerical simulations,it is demonstrated that the emission direction can be effectively manipulated by adjusting the principal axis orientation,concurrently enhancing the emitted power.In contrast to previous directional acoustic struc-tures,the compact emitter presented in this study can get rid of the size-wavelength constraint,enabling effective control of low-frequency waves.     

石墨电极的纯度对直读光谱分析的影响

石墨电极的纯度对光谱分析的影响只是在一些书中提及,表作试验研究和分析,对电极的纯度的检验未作有效论述。文中就此问题提出了作者的见解,拟定了检验电极纯度的方法。