Experimental investigation of population inversion of oxygen K-ion levels

Experimental results are reported of investigations of the optical properties of the plasma produced when an AI₂O₃ target is irradiated in vacuum by a high-power neodymiunr-glass laser system. It is shown that a number of 0 VIII and 0 VII ion levels with principal quantum numbers n = 2, 3, 4 are inversely populated. The gain at the wavelength 29 nm (4 3 transition, O VIII) under the experimental conditions is of the order of 0.01 cm^-1. For the heliumlike ions O VII, in a transition with the same principal quantum numbers (ls4p¹P₁ ls3s¹S₀, 36.9 nm), the gain is of the order of 10^-2–10^-1 cm^-1, depending on the electron density.Translated from Lazernye Sistemy, pp. 5–14 1982.     

Influence of pyridine-based ligands on photostability of MAPbI3 thin films

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Spectroscopy and continuous-wave diode-pumped laser action of Yb3+:YVO4

The growth, spectroscopic properties, and laser performance of Yb:YVO4 crystal with laser diode pumping are reported. A peak absorption cross section of 7.4 x 10(-20) cm2 at 985 nm, a radiative lifetime of 0.25 ms, and a stimulated-emission cross section of 1.25 x 10(-20) cm2 at 1008 nm for pi polarization were determined for the Yb3+ ions in YVO4. Continuous-wave laser action of Yb:YVO4 at 1020-1027 nm was demonstrated with an output power of 610 mW and a slope efficiency of 49%.     

Fabry-Perot interferometer with diffraction-scattered reflection of light

The incorporation of a phase grating into the optical system of a Fabry-Perot interferometer makes it possible to transform the incident beam of light so that the major part of energy in the reflected wave is contained in the side lobes in the far-field diffraction pattern and radiation in the zero order of diffraction along the optical axis is suppressed. Experimental results are presented, which are obtained with a grating produced by evaporating a thin-layer dielectric coating onto the input mirror of the interferometer.     

Unexpected interconversion reaction of 1,4-diaminofullerenes

A facile substitution of amine groups attached to the fullerene cage occurs when 1,4-diaminofullerenes C60[NR2]2 are allowed to react with excess of another amine R'2NH; this reaction proceeds rapidly at room temperature without any additional initiators.     

Projection electron beam lithography for nanotechnology

The parameters of projection electron beam lithography were investigated and a resolution analysis was performed. It was shown that at least three optimization parameters must be considered in the process: the field size, the focal distance, and the angle on the target. Optimization was performed with allowance for the contribution of stochastic aberration.     

Critical phenomena in high-energy lepton- and hadron-induced reactions

We argue that the nucleon seen in the Bjorken scaling region is a gas of quasi-free partons. As x decreases, for certain values of Q ² the partons in a nucleon coalesce to a liquid (saturation). Experimentally this phenomenon is manifested as the turn-over of the structure function derivatives. The phenomenon can be quantified in the framework of statistical models, percolation and other approaches to collective effects in the strongly interacting matter. Similarities and differences between the case of lepton-hadron, hadron-hadron and heavy-ion collisions are discussed.