There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Before the 1960s, all anti-Stokes emissions, which were known to exist, involved emission energies in excess of excitation energies by only a few kT. They were linked to thermal population of energy states above excitation states by such an energy amount. It was the well-known case of anti-Stokes emission for the so-called thermal bands or in the Raman effect for the well-known anti-Stokes sidebands. Thermoluminescence, where traps are emptied by excitation energies of the order of kT, also constituted a field of anti-Stokes emission of its own. Superexcitation, i.e., raising an already excited electron to an even higher level by excited-state absorption (ESA), was also known but with very weak emissions. These types of well-known anti-Stokes processes have been reviewed in classical textbooks on luminescence.1 All fluorescence light emitters usually follow the well-known principle of the Stokes law which simply states that excitation photons are at a higher energy than emitted ones or, in other words, that output photon energy is weaker than input photon energy. This, in a sense, is an indirect statement that efficiency cannot be larger than 1. This principle is

Upconversion and Anti-Stokes Processes with f and d Ions in Solids

This Feature Article gives an overview of microwave-assisted liquid phase routes to inorganic nanomaterials. Whereas microwave chemistry is a well-established technique in organic synthesis, its use in inorganic nanomaterials' synthesis is still at the beginning and far away from having reached its full potential. However, the rapidly growing number of publications in this field suggests that microwave chemistry will play an outstanding role in the broad field of Nanoscience and Nanotechnology. This article is not meant to give an exhaustive overview of all nanomaterials synthesized by the microwave technique, but to discuss the new opportunities that arise as a result of the unique features of microwave chemistry. Principles, advantages and limitations of microwave chemistry are introduced, its application in the synthesis of different classes of functional nanomaterials is discussed, and finally expected benefits for nanomaterials' synthesis are elaborated.

Microwave chemistry for inorganic nanomaterials synthesis

Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials,...

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Raman investigation of glasses x GeS 2 -Ga 2 S 3 - y MCl, Ga 2 S 3 2MCl (where M = Ag, Tl, Rb, Cs) and melt Ga 2 S 3 2CsCl has been carried out for various x and y . Raman spectra have been interpreted in the frame of the model that gallium is fourfold coordinated in the chalcogenide/halide glasses and forms complex anions such as [ GaS 3 2 Cl] 1 − . Stability of these units and type of their interconnection (corner shared or edge shared tetrahedra) depends on cation radius of a metal and correlates with glass-forming ability.

Raman spectra of gallium sulfide based glasses

Spectroscopic characteristics (spontaneous emission probabilities, radiative lifetimes, oscillator strengths, branching ratios and quantum efficiency) of Er 3+ in Ga 2 S 3 –GeS 2 –Er 2 S 3 glassy system are investigated by use of Judd–Ofelt theory. Lifetime measurements 4 S 3/2 level of Er 3+ in Ga 2 S 3 –GeS 2 –Er 2 S 3 glasses with various Er 3+ concentrations and optical gap energy are performed. Estimations of the non-radiative relaxation rate and the multiphonon relaxation rate demonstrate the occurrence of energy transfer from Er 3+ ion to the electronic states of the glass matrix. The way of the practical application of this non-radiative energy transfer is suggested.

Er3+ to glass matrix energy transfer in Ga–Ge–S:Er3+ system

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Laser-induced copper deposition from aqueous and aqueous–organic solutions: state of the art and prospects of research

The up-conversion fluorescence excited with 813 and 1550 nm light is investigated in glasses of the Ga2S3–GeS2–Er2S3 system. The influence of the glassy matrix composition and Er concentration on the luminescence and absorption spectra is studied. Increasing the Ga content relative to Ge decreases the erbium concentration quenching effect. The efficiency of up-conversion fluorescence has a strong dependence on thermal history of the sample. Annealing of the glasses and decreasing the synthesis temperature increase the luminescence intensity.

Yu. S. Tver’yanovich

Papers

Raman spectra of gallium sulfide based glasses

Er3+ to glass matrix energy transfer in Ga–Ge–S:Er3+ system

Laser-induced copper deposition from aqueous and aqueous–organic solutions: state of the art and prospects of research

Up-conversion fluorescence in Er-doped chalcogenide glasses based on GeS2–Ga2S3 system

Chalcogenide glasses containing metal chlorides