Precise wavelength determination of the 4s24p 2P3/2 - 2P1/2 transition in Mo11+ and Ru13+ ions

The 4s24p 2P3/2 – 2P1/2 magnetic dipole transition in Ga-like ions is interested in developing of high precise highly charged ion clock [Phys. Rev. A, 99, 02213(2019)]. In this work, we present direct observations of the transition in Mo11+ and Ru13+ ions at an electron beam ion trap. Internal and external calibration methods are used for determining the wavelength of the Mo11+ and Ru13+ lines, respectively. Both measurements reach precision levels of a few ppm. Compared with the available values, the current results significantly improve the experimental uncertainty.

Luminescence performance of laser synthesized Al2O3:Eu3+ nanophosphors depending on synthesis conditions

Al2O3:Eu3+ nanophosphors were prepared by laser vaporization method in a flowing mixture of Ar/He and O2. Luminescence properties of Al2O3:Eu3+ nanophosphors are predominantly determined by Eu3+ ions red emission with inhomogeneously broadened bands in the region of 550-750 nm corresponding to 5D0 →7FJ transitions of Eu3+ (J = 0 - 4). Hypersensitive electric dipole transition 5D0 →7F2 dominates in the spectrum and is responsible for the red emission. The effect of crystallite size on luminescence properties of Al2O3:Eu3+ nanocrystals was observed. It was shown that the introduction of oxygen during the synthesis improves the luminescence performance. The obtained chromaticity coordinates and high absolute QY (~ 14%) indicate the possibility of using red nanophosphors based on Al2O3:Eu3+.

Studies on the photoluminescence and thermoluminescence properties of CaZrO3:xEu3+ phosphor for dosimetric application

Series of CaZrO3:xEu3+ (x=0.01, 0.02, 0.03, 0.04 and 0.05) phosphors have been prepared by low temperature sol-gel auto combustion method. The structure and morphology of the samples were investigated by X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM). The energy-dispersive X-ray spectroscope (EDX) was employed to analyze the elemental composition of the phosphor. The XRD patterns indicated that the sample was single phase at 350 ◦C with a perovskite structure. The optimum temperature for the single- phase and crystalline phosphors of CaZrO3:xEu3+ was 700 ◦C. Study of photoluminescence (PL) at room temperature showed that the phosphors can be excited by light with a wavelength of 391 nm. The results of emission spectrum showed that the red luminescence of CaZrO3:xEu3+ due to electric dipole transition of 5D0→7F2 was dominant at wavelength of 615 nm and weaker transition at wavelength of 590 nm which was due to magnetic dipole transition of 5D0→7F1. For the thermoluminescence (TL) study the prepared sample irradiated by X-ray lamp, the TL curve was then recorded at fixed heating rate of 2 ◦C/s. The TL glow curve showed well single peak at a temperature of 165 ◦C. The effect of Eu3+ concentration at fixed X-ray exposure time was studied and maximum TL occurred at x=0.02. Also the variation of TL intensity with X-ray time (5 to 15 min) showed linear response with dose. The TL glow peak shows more stability and less fading in prepared phosphor which is suitable for TL dosimetry.

THE COORDINATION COMPOUNDS Gd (III) AND Dy(III) WITH SOME β-DIKETONES

New complexes of Dy (III) and Gd (III) with b-diketones containing unsaturated and aryl substituents were synthesized. Metal polymers based on synthesized complexes were obtained by the method of radical polymerization. The composition and structure of synthesized complexes and metal polymers are established. It is shown that during polymerization the coordination environment of the central ion remains unchanged. The spectral-luminescent cha­racteristics of the synthesized compounds were studied. The presence of water molecules in the immediate coordination environment causes a low intensity of emission of monomeric dysprosium complexes. In the luminescence spectra of metal polymers, there are bands magnetic dipole transition (4F9 → 6H15/2) and electric dipole transition (4F9 → 6H13/2). The close energies of the triplet level of the ligand and the resonant level of the dysprosium ion cause low emission characteristics of the synthesized dysprosium complexes.

Towards New Chiroptical Transitions Based on Thought Experiments and Hypothesis

We studied supramolecular chirality induced by circularly polarized light. Photoresponsive azopolymers form a helical intermolecular network. Furthermore, studies on photochemical materials using optical vortex light will also attract attention in the future. In contrast to circularly polarized light carrying spin angular momentum, an optical vortex with a spiral wave front and carrying orbital angular momentum may impart torque upon irradiated materials. In this review, we summarize a few examples, and then theoretically and computationally deduce the differences in spin angular momentum and orbital angular momentum depending on molecular orientation not on, but in, polymer films. UV-vis absorption and circular dichroism (CD) spectra are consequences of electric dipole transition and magnetic dipole transition, respectively. However, the basic effect of vortex light is postulated to originate from quadrupole transition. Therefore, we explored the simulated CD spectra of azo dyes with the aid of conventional density functional theory (DFT) calculations and preliminary theoretical discussions of the transition of CD. Either linearly or circularly polarized UV light causes the trans–cis photoisomerization of azo dyes, leading to anisotropic and/or helically organized methyl orange, respectively, which may be detectable by CD spectroscopy after some technical treatments. Our preliminary theoretical results may be useful for future experiments on the irradiation of UV light under vortex.

Quantum exceptional chamber induced by large nondipole effect of a quantum dot coupled to a nano-plasmonic resonator

Exceptional points (EPs) are the singularities of a non-Hermitian system where the eigenenergies and eigenstates simultaneously coalesce, a topological property that gives rise to a plethora of exotic phenomena. Probing the EPs and associated effects requires the system to go through the EPs. However, the ultrahigh sensitivity of an isolated EP to the external disturbances makes accessing the EPs difficult. To overcome this limit, many approaches have been presented to form the exceptional line/ring and surface. Here, we demonstrate that a quantum exceptional chamber, which is a three-dimensional collection of the EPs, can be constructed in the coupled plasmon-quantum dot (QD) systems by the nondipole effect of the QD. For an asymmetric QD adjacent to a plasmonic nanoparticle, it is found that the contributions of multipole transitions to the coupling strength can be larger than that of dipole transition. The orientation-dependent quantum interference between the dipole and multipole transitions can lead to controllable switch between the weak and strong coupling, and provides an extra degree of freedom to form a high-dimension EP space. Our approach provides a robust platform for accessing the quantum EPs and related applications.

Nonreciprocal second harmonic generation in a magnetoelectric material

Mirror symmetries are of particular importance because they are connected to fundamental properties and conservation laws. Spatial inversion and time reversal are typically associated to charge and spin phenomena, respectively. When both are broken, magnetoelectric cross-coupling can arise. In the optical regime, a difference between forward and backward propagation of light may result. Usually, this nonreciprocal response is small. We show that a giant nonreciprocal optical response can occur when transferring from linear to nonlinear optics, specifically second harmonic generation (SHG). CuB2O4 exhibits SHG transmission changes by almost 100% upon reversal of a magnetic field of just ±10 mT. The observed nonreciprocity results from an interference between magnetic-dipole and electric-dipole SHG. Although the former is inherently weaker than the latter, a resonantly enhanced magnetic-dipole transition has a comparable amplitude as a nonresonant electric-dipole transition, thus maximizing the nonreciprocity. Multiferroics and magnetoelectrics are an obvious materials platform to exhibit nonreciprocal nonlinear optical functionalities.