Andrei Naumov

Russian Academy of Sciences | RAS · Institute of Spectroscopy

This paper presents a cost-effective approach for the template-assisted electrodeposition fabrication of substrates for surface-enhanced Raman scattering (SERS) with metal nanowires (NWs) grown in pores of polymer track-etched membranes (TM). This technique allows the synthesis of NWs array with its certain surface density and diameter (from dozen...

б0 лет назад, в 1952 г., Э.В. Шпольский и его сотрудники впервые наблюдали эффект возникновения квазилинейчатых спектров сложных органических соединений в специально подобранных растворителях при низких температурах. Спустя 20 лет, в 1972 г., коллективом под руководством Р.И. Персонова был обнаружен эффект лазерного возбуждения тонкоструктурных спе...

The refractive index n is one of the most important materials parameters of solids and, in recent years, has become the subject of significant interdisciplinary interest, especially in nanostructures and meta-materials. It is, in principle, a macroscopic quantity, so its meaning on a length scale of a few nanometers, i.e., well below the wavelength...

We report the discovery of a GeV-associated phenomenon which is strong (up to an order) stochastic reversible enhancements of photoluminescence intensity in a single GeV diamond synthesized with the high-pressure, high-temperature technique. We were lucky to observe this effect with only one crystal among dozens of similar microdiamonds. Each rise...

In this Colloquium, we discuss the main principles, achievements and perspectives in the field of highly parallel luminescence spectroscopy and imaging of single molecules (SM) in transparent solids. Special attention will be given to SM detection at low temperatures, where ultranarrow and bright zero-phonon lines (ZPL) of emitting centres are achi...

In spite of decades of comprehensive studies phenomenon of single semiconductor colloidal quantum dots (QD) photoluminescence (PL) blinking require theoretical retreatment. Here we present enhanced model which proposes, that the...

Time-resolved analysis of photon cross-correlation function g(2)(τ) is applied to photoluminescence (PL) of individual submicrometer size MAPbI3 perovskite crystals. Surprisingly, an antibunching effect in the long-living tail of PL is observed, while the prompt PL obeys the photon statistics typical for a classical emitter. We propose that antibun...

Microdiamonds with color centers have unique photophysical properties. We discover extremely narrow spectral lines with full width at half maximum down to 0.5 nm (≈390 GHz at wavelength 630.15 nm) at room temperature in photoluminescence of numerous high-pressure–high-temperature microdiamonds. Correlation spectroscopy proves that these lines origi...

Based on the data on the spectral and photophysical parameters of the metal complexes of tetraazaporphyrins and phthalocyanines, the effect of the central metal ion on the manifestation of spin-orbit interaction is considered. For complexes of phthalocyanines with Mg(II), Zn(II), Pd(II), and Pt(II) ions, the absorption spectra, luminescence spectra...

The most relevant technique for portable (on-chip) sensors is Surface Enhanced Raman Scattering (SERS). This strategy crashes in the case of large (biorelevant) molecules and nano-objects, whose SERS spectra are irreproducible for “homeopathic” concentrations. We suggested solving this problem by SERS-mapping. We analyzed the distributions of SERS...

The investigation of the mechanical properties of polymer track-etched membranes (TMs) has attracted significant attention in connection with the extended region of their possible applications. In the present work, the mechanical stress fields around the pores of an elongated polyethylene terephthalate TM and around the 0.3 mm holes in model polyme...

Полупроводниковые нанокристаллы (квантовые точки, КТ) обладают уникальными фотофизическими свой­ствами, что открывает широкие возможности их прикладного использования в методах и инструментах современной фотоники. В данной статье рассматриваются возможные приложения КТ. Обсуждаются как существующие устройства, так и перспективы разработки новых мет...

The structural characteristics of polymer track-etched membranes (TM) were obtained by atomic force microscopy (AFM) for a set of samples (polypropylene, polycarbonate, polyethylene terephthalate, with average pore diameters ~183, 375, and 1430 nm, respectively). The analysis of AFM experimental data was performed by using a specially developed tec...

The temperature-dependent luminescence spectra were analyzed to determine the parameters of the electron-phonon interaction (Huang-Rhys factor and the average phonon energy) for nanocomposites with colloidal CdSe/CdS/ZnS quantum dots (deposited on the surface of a glass substrate and embedded in a thin polymer film of polyisobutylene, and in a froz...

The current paper demonstrates theoretical analysis of two types of spectral curves for several configurations of system of two-level light emitters, considering the influence of local field and close environment inside a transparent medium. Probe field absorption spectra and resonant fluorescence spectra are calculated under excitation of a strong...

The effect of hyper enhancement of Raman scattering appearing on microcracks of the metal deposition (silver, gold) of uniaxially stretched track polymer membranes (TMs) is investigated. Deformation of membranes with a combination of high surface density and small diameter of their pores leads to the development of many microcracks in the metal coa...

В статье приведен краткий обзор работ, посвященных синтезу, исследованию фотофизических и спектральных свой­ств и анализу применений полупроводниковых нанокристаллов – квантовых точек (КТ). Обсуждаются фундаментальные закономерности, связывающие морфологию КТ с их оптико-спектральными характеристиками, а также некоторые теоретические модели, позвол...

A way of analyzing the spatial distribution of a solution on a substrate with a developed nanostructured surface (a metallized metasurface) is proposed. The technique is based on epi-luminescence microscopy and can be used to calculate the gain of the SERS signal on a surface with a complex highly-developed structure, where standard ways of estimat...

Fluorescence imaging of single quantum light emitters (atoms, molecules, quantum dots, color centers in crystals) is an inherent experimental problem of modern photonics and its numerous applications. In these measurements, highly sensitive cameras are of the key significance. Recent progress in technologies of charge-coupling devices (CCD) and com...

Antibunching effect is typically observed in individual systems possessing photoluminescence (PL) blinking and vice versa. Contrary to this common perception, absence of antibunching in strongly blinking methyl ammonium led tri‐iodide (MAPbI3) perovskite crystals of sizes from tens to hundreds of nanometers regardless of the excitation power densit...

We studied the spectral dynamics of single fluorescent dye molecules embedded in ultrathin films (5 - 100 nm) of the amorphous polymer polyisobutylene at cryogenic temperatures and its variation with film thickness. Noticeable portion of molecules in the ensemble show a behavior which is inconsistent with the standard tunneling model: Their spectra...

Colloidal semiconductor nanocrystals (quantum dots, QD) manifest specific temperature dependent luminescence. Here we analyse temperature dependences of CdSe QD luminescence spectrum shift for different composites: polymers, glasses, crystals. The analysis was performed in the terms of electron-phonon coupling, that allows to find and compare the p...

We introduce a novel experimental approach for mapping the effective local value of the refractive index in solid films and the analysis of related local-field enhancement effects using imaging and spectroscopy of single quantum emitters.

A way of improving the energy efficiency of diffraction optical elements (DOEs) that form two-lobe light fields whose intensity distribution rotates in propagation is studied. Such DOEs find application in ultrahigh resolution microscopy to modify the spread function of a point light source via phase spatial light beam modulation, allowing all thre...

Luminescence spectroscopy experiments were realized for single colloidal quantum dots CdSe/ZnS in a broad temperature range above room temperature in a nitrogen atmosphere. Broadening and shifts of spectra due to the temperature change as well as due to spectral diffusion processes were detected and analyzed. A linear correlation between the positi...

Fluorescence excitation spectra of single terrylene molecules in transparent naphthalene and polyethylene matrices at ultralow (30–100 mK) temperatures have been studied under the conditions where the widths of zero-phonon spectral lines are determined only by the lifetime T1 of the excited electronic state. The experimentally observed dispersion o...

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 poss...

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 poss...

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...

The influence of the concentration and the laser excitation wavelength on the width and luminescence spectrum maximum of CdSe/CdS /ZnS quantum dots in the toluene solution and doped on the glass plate was studied. It was shown that the wavelength of the exciting laser does not affect the width and peak center of the luminescence spectrum of the sam...

A new model of single quantum dot (QD) spectral diffusion based on variations of the electron-phonon coupling strength was introduced. It was applied successfully to describe intriguing effect of the correlation between the positions of the maxima and the widths of single QDs luminescence spectra. The model was able to describe the linear dependenc...

We have used fluorescence nanoscopy for direct imaging of adsorption of individual colloidal quantum dots of diameter ~10 nm (spherical core/shell CdSeS/ZnS semiconductor nanocrystals, functionalized by organic oleic acid ligands) in nanopores of a nuclear filter (a polypropylene track membrane with pores of diameter ~500 nm). We have shown that wh...

The processing of images of point-like fluorescing objects, obtained by a matrix detector in the scheme of a luminescent microscope, is considered. Analysis of model images with parameters close to experimental images of flickering single CdSe/ZnS quantum dots is presented. A scheme for obtaining information on fluctuations in fluorescence intensit...

The possibility of detecting signals of a two-pulse incoherent photon echo in a thin layer of double-coated semiconductor colloidal quantum dots spread on the surface of a glass substrate at T = 10 K is demonstrated. Possible mechanisms of ultrafast optical dephasing detected at the given temperature are discussed.

A technique for image processing and the localization (tracking) of fluorescent nanoparticles is developed on the basis of the Hough transform. Features of data analysis in the Hough parametric space that are due to the need to display the coordinates of single point emitters in 3D space are discussed. Examples are given of tracking single point em...

The possibility of determining the distance between two closely spaced blinking single colloidal quantum dots using super-resolution far-field luminescence microscopy is considered. Numerical simulation of microscope images of a single pair of point light emitters is performed for different modes of luminescence blinking observed in experiments wit...

Zero-phonon spectral lines of single Mg-tetraazaporphyrin molecules in a polymer matrix and their spectral trails are recorded using cryogenic fluorescence nanoscopy at a temperature of 6 K. Spectral diffusion (stochastic jumps of zero-phonon lines) in an anomalously wide spectral range up to several tens of inverse centimeters is revealed. The str...

A simple and effective technique for fabricating homogeneous films of colloidal quantum dots is developed. Incoherent photon echo signals in the prepared thin films of quantum dots are detected and studied in a wide range of cryogenic temperatures (from 4.5 to 50 K). The temperature dependence of the inverse optical dephasing time is constructed an...

The question of the axial coordinate determination accuracy is quite sophisticated in far field 3D fluorescence nanoscopy. The accuracy of a point emitter axial coordinate reconstruction depends among other things on the conversion efficiency of the phase mask and the microscope objective instrumental function. It was found that the instrumental fu...

We introduce an experimental approach for mapping effective local values of dielectric characteristics of solid films and the analysis of the related local-field effects. The characterisation technique is based on the imaging and spectroscopy of single chromophore molecules at cryogenic temperatures. The progress in the theory of fluorescence enhan...

We propose a theoretical explanation of spontaneous transitions between dim and bright fluorescence intensity states observed experimentally in a microcrystal of diamond with germanium-vacancy colour centres driven by a continuous wave laser. We use a generalized system of optical Maxwell-Bloch equations derived for an emitter in an ensemble of mot...

The results of low-temperature measurements of spectral trails (temporal evolutions of individual fluorescence excitation spectra) of single molecules Mg-tetraazaporphyrin embedded in polyisobutylene are presented. Spectral trails were recorded in a broad spectral range (up to 4000 GHz) at a temperature 6K. Spectral diffusion in a broad spectral ra...

Low temperature dynamics (tunneling and vibrational relaxation) in doped polyisobutylene film has been reinvestigated using 2-pulse incoherent photon echo (2IPE) and compared with single-molecule spectroscopy (SMS) data. It has been shown that in a very wide range of low temperatures the 2IPE gives optical dephasing times which correspond to the na...

A simple and effective technique for depositing thin films of semiconductor colloidal quantum dots (QD) on glass substrates is developed. Samples with CdSe/CdS/ZnS quantum dots are fabricated and investigated via luminescence microspectroscopy. Four-wave mixing signals are recorded at room temperature in a solution and in a thin film of quantum dot...

Simple procedure to prepare samples containing semiconductor quantum dots was developed. Test photon echo measurements in the ensemble of quantum dots spread on a glass substrate were performed to study optical dephasing processes.

The photon echo (PE) spectroscopy and single-molecule spectroscopy (SMS) may be combined to give a very powerful tool for comprehensive study of low-temperature dynamics in dye-doped disordered solids (polymers, glasses). At the same time, this type of studies are likely to reveal discrepancies when comparing characteristic times of optical dephasi...

We describe the specific algorithms for statistical processing of the data on fluorescence excitation spectra and images for large number of single dye molecules in thin solid film. Analysis of the data allowed mapping of the local fields and the effective refractive index in a frozen solid film. An estimation of the volume attributed to the effect...

The work concerns the feasibility of 3D optical diagnostic of porous media with subdifraction spatial resolution via epi-luminescence microscopy of single semiconductor colloid nanocrystals (quantum dots, QD) CdSe/ZnS used as emitting labels/nanoprobes. The nanoprecise reconstruction of axial coordinate is provided by double helix technique of poin...

In this poster talk we discuss a possibility to realize the combined analysis of the temperature dependences of the zero-phonon line widths and fluorescence images of single molecules in thin polymer films. Such analysis is aimed to obtain the local characteristics of low-temperature vibrational dynamics (individual parameters of quasi-localised lo...

Himangshu Prabal Goswami opened the discussion of the paper by Jörg Wrachtrup: When you describe the Hamiltonian, the coupling between the ancillary and sensor spin is g and the coupling between the sensor and sample spin is J i. Are these frequency dependent? If not, what is the quantitative range of g and J i under which they can be treated as sy...

In this work, we study the relation between the widths of the zero-phonon lines (ZPL) of single impurity molecules (SM) in solid matrices with local effective values of the refractive index n. Since at ultralow temperatures the width of SM ZPL is determined mainly by the radiative lifetime T1, while the local-field effects produce the function T1(n...

The temporal evolution of fluorescence intensity of a single blinking CdSe/ZnS nanocrystal (quantum dot, QD) has been measured with continuous wave (CW) laser excitation at room temperature. Tracks exhibit ON-/OFF-fluctuations with large amplitude and intensity fluctuations with small amplitude in the ON-interval. The QD photon distribution functio...

Most experimental observations of physical processes are naturally accompanied by " blind " (" dead ") times, which in principle can distort the result of measurements. Here we analyze how the presence of blind times in measurements changes the measured statistics of blinking fluorescence of single quantum dots. We show that information can be extr...