Interface Excitons in Krmnen Clusters : The Role of Electron Affinity in the Formation of Electronic Structure

The formation of the electronic structure of small Kr_m clusters (m<150) embedded inside Ne_N clusters (1200<N<7500) has been investigated with the help of fluorescence excitation spectroscopy using synchrotron radiation. Electronically excited states, assigned to excitons at the Ne/Kr interface, 1i and 1'i were observed. The absorption bands, which are related to the lowest spin-orbit split atomic Kr 3P1 and 1P1 states, initially appear and shift towards lower energy when the krypton cluster size m increases. The characteristic bulk 1t and 1't excitons appear in the spectra, when the cluster radius exceeds some critical value, R_cl>Delta_1i . Kr clusters comprising up to 70 atoms do not exhibit bulk absorption bands. We suggest that this is due to the penetration of the interface excitons into the Kr_m cluster volume, because of the negative electron affinity of surrounding Ne atoms. From the energy shift of the interface absorption bands with cluster size an unexpectedly large penetration depth of delta_1i =7.0+/-0.1 A is estimated, which can be explained by the interplay between the electron affinities of the guest and the host cluster

Quantitative analysis of cell types during growth and morphogenesis in Hydra

Tissue maceration was used to determine the absolute number and the distribution of cell types in Hydra. It was shown that the total number of cells per animal as well as the distribution of cells vary depending on temperature, feeding conditions, and state of growth. During head and foot regeneration and during budding the first detectable change in the cell distribution is an increase in the number of nerve cells at the site of morphogenesis. These results and the finding that nerve cells are most concentrated in the head region, diminishing in density down the body column, are discussed in relation to tissue polarity

Near-term experiments and long-term goals at INURA pulsed ion accelerator in Nazarbayev University

Nazarbayev University works on establishing a research program on inertial confinement fusion, high energy physics and critical states of matter. Long term plans include building a new multi-MV, ~10 to several hundred GW/cm2 ion accelerator facility which will be used in studies of material properties at extreme conditions. Two design options are being considered..

Photonic molecules and spectral engineering

This chapter reviews the fundamental optical properties and applications of pho-tonic molecules (PMs) - photonic structures formed by electromagnetic coupling of two or more optical microcavities (photonic atoms). Controllable interaction between light and matter in photonic atoms can be further modified and en-hanced by the manipulation of their mutual coupling. Mechanical and optical tunability of PMs not only adds new functionalities to microcavity-based optical components but also paves the way for their use as testbeds for the exploration of novel physical regimes in atomic physics and quantum optics. Theoretical studies carried on for over a decade yielded novel PM designs that make possible lowering thresholds of semiconductor microlasers, producing directional light emission, achieving optically-induced transparency, and enhancing sensitivity of microcavity-based bio-, stress- and rotation-sensors. Recent advances in material science and nano-fabrication techniques make possible the realization of optimally-tuned PMs for cavity quantum electrodynamic experiments, classical and quantum information processing, and sensing.Comment: A review book chapter: 29 pages, 19 figure

Giant resonant light forces in microspherical photonics

Resonant light pressure effects can open new degrees of freedom in optical manipulation with microparticles, but they have been traditionally considered as relatively subtle effects. Using a simplified two-dimensional model of surface electromagnetic waves evanescently coupled to whispering gallery modes (WGMs) in transparent circular cavities, we show that under resonant conditions the peaks of the optical forces can approach theoretical limits imposed by the momentum conservation law on totally absorbing particles. Experimentally, we proved the existence of strong peaks of the optical forces by studying the optical propulsion of dielectric microspheres along tapered microfibers. We observed giant optical propelling velocities ∼0.45 mm s−1 for some of the 15-20 µm polystyrene microspheres in water for guided powers limited at ∼43 mW. Such velocities exceed previous observations by more than an order of magnitude, thereby providing evidence for the strongly enhanced resonant optical forces. We analyzed the statistical properties of the velocity distribution function measured for slightly disordered (∼1% size variations) ensembles of microspheres with mean diameters varying from 3 to 20 µm. These results demonstrate a principal possibility of optical sorting of microspheres with the positions of WGM resonances overlapped at the wavelength of the laser source. They can be used as building blocks of the lossless coupled resonator optical waveguides and various integrated optoelectronics devices

Photocatalytic Nanoparticulate ZrxTi1-xO2 Coatings with Controlled Homogeneity of Elemental Composition

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