


Vol 126, No 1 (2019)
- Year: 2019
- Articles: 18
- URL: https://ogarev-online.ru/0030-400X/issue/view/10104
Spectroscopy of Condensed State
Investigation of a Sequence of Dynamical Decoupling Pulses for Dipole-Coupled Spin Systems with Inhomogeneous Broadening
Abstract
The protocol of dynamic decoupling using a sequence of resonance RF pulses with different shapes in a system of dipole-coupled electron/nuclear spins with inhomogeneous broadening of the resonance line has been theoretically studied. The choice of optimal RF pulse parameters for implementation of long-lived broadband quantum memory based on these spin systems is discussed.



Influence of Europium(III) β-Diketonate Complex on Orientational Responses in Ultrafast Optical Kerr Effect
Abstract
Experiments on recording the ultrafast optical Kerr effect (OKE) in solution of europium(III) β‑diketonate complexes in toluene at a concentration of 10–2 mol/L showed that the total OKE signal is not a superposition of two contributions, one of which is related to the vibrational–rotational dynamics of toluene molecules, while the other is due to the vibrational–rotational dynamics of the europium(III) complexes. This immediately indicates that the europium(III) complexes essentially change the structure of liquid toluene, which is reflected in the character of an orientational response in picosecond range.



Physical Optics
The Possibility of Forming Two-Lobe Vortex Light Fields Using a Modified Liquid-Crystal Focusator
Abstract
The possibilities of forming light fields with intensity distribution in the form of two maxima rotating during propagation using a liquid-crystal modal device are analyzed. The rate of intensity distribution rotation depending on the radius of curvature of the wave incident on the modulator, as well as the energy efficiency of the formed fields, are estimated.



Nonlinear Optics
The Multifocus Structure of Radiation upon Femtosecond Filamentation of an Optical Vortex in a Medium with an Anomalous Group Velocity Dispersion
Abstract
We analyze numerically the femtosecond filamentation of a vortex beam with the topological charge m = 1 at wavelength λ0 = 1800 nm in fused silica under anomalous group velocity dispersion conditions. We show that, as a pulse with a fivefold excess of its power over the critical power propagates through the medium, a multifocus ring structure of radiation with a peak intensity of higher than 1013 W/cm2 and surface energy density of about 0.2 J/cm2 is formed. The self-action of the optical vortex is accompanied by the transformation of the spectral energy mainly into the Stokes region. A comparison is made with the case of a normal dispersion of the group velocity upon the self-action of a vortex beam at the wavelength of λ0 = 400 nm.



Quantum Optics
The Formation of Single-Photon IR Wave Packets with an Orbital Angular Momentum Using Vortex Phase Plates
Abstract



Maps of Broadband Quantum Memory Based on an Atomic Frequency Comb
Abstract
The influence of the parameters of an inhomogeneously broadened optical transition in the shape of an atomic frequency comb on dispersion effects in the quantum-memory protocol implemented in such an atomic system is investigated. The results allowed maps to be constructed of dispersion and quantum efficiency for implementation of the studied protocol in rare-earth-doped crystals that are promising for creation of a quantum repeater.



Optical Materials
A New Strategy to Design Photostable Luminescent Materials Based on Lanthanide(III) β-Diketonate Complexes for Advanced Photonic Applications
Abstract
An analysis of the prospects for creating new luminescent molecular photonics materials based on mesogenic lanthanide(III) β-diketonate complexes is presented. We consider vitrified films that combine intense monochromatic luminescence, high optical quality, and complete resistance to UV radiation with the ability to change their photophysical properties (for example, the absorption band width and luminescence intensity) depending on the local structure and under external actions, such as UV radiation and temperature. The problems of control of the photophysical properties of these films and the possibility of their application as working media of high-tech luminescent materials and devices (for example, luminescent sensors of temperature, oxygen, and UV radiation, as well as light-conversion materials) are discussed.



Optics of Low-Dimensional Structures, Mesostructures, and Metamaterials
Analysis of the Temperature Dependence of the Exciton Luminescence Spectra of Cadmium Selenide Quantum Dots Grown in a Liquid Crystal Matrix
Abstract
The temperature dependences of the positions of maxima of exciton bands in the luminescence spectra of liquid crystal nanocomposites with CdSe quantum dots with sizes of 1.8 and 2.3 nm at T = 77–300 K have been analyzed. The analysis under the theoretical model taking into account the electron–phonon interaction inside quantum dots has made it possible to calculate the values of the Huang–Rhys factor and average phonon energy in nanocrystals under study.



Direct Observation of a Quasilocalized Low-Frequency Vibrational Mode in the Fluorescence Excitation Spectrum of a Single Impurity Molecule in a Polymer Matrix
Abstract
The possibility of direct observation of a quasi-localized elementary excitation of the phonon type in polyisobutylene has been demonstrated by detecting the fluorescence excitation spectrum of a Mg‑tetrazaporphyrin single probe molecule in a wide spectral range at a temperature of 6 K. The parameters of the quasilocalized low-frequency vibrational mode have been measured—the frequency (energy) in the case, when impurity molecule is in excited electronic state (ωe = 13.94 ± 0.21 cm–1) and the halfwidth of the mode spectrum (γ = 3.82 ± 0.66 cm–1). The measured energy of the low-frequency vibrational mode coincides with the position of a boson peak maximum in the spectrum of vibrational states of the polymer, which indicates that the weak coupling approach can be applied to the considered case of the electron–phonon interaction of an organic dye molecule with the local environment in a polymer matrix.



Compensation of Global Drift in Long-Term Measurements in Fluorescent Nanoscopy of Quantum Dots
Abstract
An approach to improving the accuracy of image processing of fluorescent shimmering single quantum dots is presented. It is based on estimating the parameters of a function describing global drift using information on a sufficiently long series of images of single quantum dots. The results of processing a series of frames obtained in experiments with single CdSe/ZnS quantum dots are presented.



Optical Sensors and Transducers
Two-Wave Laser Stereolithography for Fabrication of IR Sensors for Surface-Enhanced Spectroscopy
Abstract
The results of applying two-photon femtosecond laser photopolymerization for fabrication of structures for sensitive IR sensors are reported. Two methods of sensor fabrication, a two-wave laser stereolithography and an electron-beam lithography, are compared. The possibility of applying the obtained structures for investigation of the effect of surface-enhanced IR absorption (SEIRA) with a STED-compatible oligomer pentaerythritol tetraacrylate (PETTA) as an analytical layer is demonstrated.



Room Temperature Optical Thermometry Based on the Luminescence of the SiV Defects in Diamond
Abstract
Diamond microcrystals containing silicon-vacancy (SiV) defects were synthesized by using a high-pressure high-temperature treatment of a mixture of pertinent organic-inorganic precursors. Photoluminescence of the SiV defects and its temperature dependence (80–400 K) was studied. A strong sharp zero-phonon line (ZPL) at 738 nm was recorded at all temperatures under 488 nm laser excitation. In particular the thermally induced shift of the ZPL was found promising for optical temperature sensing in the near infrared spectral range at biomedically relevant temperatures.



Nanophotonics
Resonant Nonradiative Energy Transfer in Hybrid Associates of Thionine Molecules and Ag2S Colloidal Quantum Dots with Different Luminescence Mechanisms
Abstract
We have considered the resonant nonradiative energy transfer in hybrid associates of thionine dye (TH+) molecules and Ag2S colloidal quantum dots (QDs) passivated with thioglycolic acid (Ag2S/TGA) and Ag2S QDs stabilized with gelatin (Ag2S/Gel). Used samples of Ag2S QDs possess luminescence, which arises by the exciton mechanism, as well as by the recombination mechanisms of holes with electrons localized at luminescence centers and of electrons with holes localized at the luminescence centers. The quenching of luminescence of Ag2S/TGA QDs (1.8 nm) with a maximum at 630 nm and a decrease in the luminescence lifetime from 13.7 to 6.5 ns, which occurs upon association with TH+ molecules, have been established. On the contrary, for associates of Ag2S/TGA QDs (5.5 nm) with TH+ molecules, we have observed the quenching of luminescence of the dye and a decrease in the lifetime of this luminescence from 0.43 to 0.3 ns, as well as an enhancement of luminescence of QDs. In the case of hybrid association with TH+ molecules, the luminescence enhancement of Ag2S/Gel QDs (1.6 nm) has been established, which results from the recombination of free holes with electrons localized at luminescence centers. Based on our analysis of the luminescence kinetics of the dye, we have inferred the occurrence of resonant nonradiative energy transfer from TH+ molecules to centers of recombination luminescence in Ag2S/TGA (5.5 nm) and in Ag2S/Gel (1.6 nm) QDs with its maxima at 950 and 1205 nm, respectively. For Ag2S/TGA QDs (2.2 nm), which luminesce with a maximum at 620 nm by the exciton mechanism, we have observed a significant overlap both between the luminescence spectra of QDs and TH+ and between their absorption spectra. Close parameters of the luminescence kinetics for both the initial components and their associates indicate the energy transfer, which is realized in opposite directions.



Models of Semiconductor Quantum Dots Blinking based on Spectral Diffusion
Abstract
Three models of single colloidal quantum dot emission fluctuations (blinking) based on spectral diffusion were considered analytically and numerically. It was shown that the only one of them, namely the Frantsuzov and Marcus model reproduces the key properties of the phenomenon. The other two models, the Diffusion-Controlled Electron Transfer (DCET) model and the Extended DCET model predict that after an initial blinking period, most of the QDs should become permanently bright or permanently dark which is significantly different from the experimentally observed behavior.



Configuration Resonance and Generation Rate of Surface Plasmon Polaritons Excited by Semiconductor Quantum Dots near a Metal Surface
Abstract
We discuss particular features of generation of surface plasmon polaritons in a metal–dielectric planar interface that is coupled to semiconductor quantum dots by near-field interactions. As a model of working medium for performing numerical experiment, we use a gold metal surface onto which a polyethylene terephthalate film containing CdSe semiconductor spherical quantum dot is deposited. The problem of optimizing the radius of a quantum dot and its distance to a metal surface is solved for achieving the maximum transfer efficiency of the quantum dot energy for the generation of surface plasmon polaritons. Dispersion effects of the surface wave generation rate associated with deviations of the radius of quantum dots and their distance to the metal surface from the corresponding average values are taken into account.



Biophotonics
Three-Dimensional Luminescence Tomographic Visualization of Biological Tissues
Abstract
We propose a method for obtaining a fluorescence tomographic image for visualization and diagnosis of tissues of a living organism. The method is based on the excitation of the luminescence of multicolor upconverting nanoparticles localized in the depth of the biological tissue or a phantom imitating it by IR light. By recording the changes in the shape of the spectrum of the intensity of luminescence radiation from luminescent nanoparticles on the surface of the tissue, it is possible to obtain information about the depth of their occurrence. To implement this approach, upconverting nanoparticles were synthesized on the base of β-NaYF4 crystal matrix doped with rare-earth elements Yb3+, Er3+, and Tm3+. The luminescence spectra of the produced nanoparticles upon excitation at a wavelength of 980 nm contain three narrow bands with maxima at wavelengths 540, 655, and 800 nm.



Deferred Registration of Nanophosphor Photoluminescence As a Platform for Optical Bioimaging
Abstract
Detection systems with deferred registration of luminescence signals are promising for performing complex tasks of imaging of biological objects due to their simplicity and low cost. In the present work, β‑NaYF4:Tm3+Yb3+/NaYF4 nanocrystals with anti-Stokes photoluminescence have been used in deferred registration systems. It has been shown that there is a significant time delay between the exciting laser pulse and luminescence signal, which makes it possible to use this class of nanoparticles in the creation of wide-field imaging systems with deferred registration. The possibility of using nanoparticles for detecting a photoluminescence signal in the second transparency window of biotissue has been demonstrated. This system can be based on the resonance excitation and detection of the photoluminescence signal of Yb3+ ions.



Artificial Electron-transport Chains Based on Green Fluorescent Protein
Abstract
In this paper, we combined a photoinduced electron donor—an improved green fluorescent protein (EGFP)—and protein oxidants within the same chimeric polypeptide chain. Comparison of the photostability of EGFP and chimeric proteins both in the absence and in the presence of non-protein-bound oxidants in solution showed the efficiency of the created model electron transport chains.


