Kamil R. Karimullin

• PhD
• Senior Researcher at Russian Academy of Sciences

The analysis of various modes of multichannel information recording and readout in conditions of a stimulated (accumulated and long-living) photon echo in the crystals doped with rare earth ions which are known as Van-Fleck paramagnets has been performed in order to utilize them in the operation of low-temperature optical echo-processors.

Luminescence imaging has been adapted to facilitate alignment and focusing of multiple non-collinear laser beams in pump–probe experiments. The technique has been validated in an experiment on four-wave mixing in a doped polymer placed into a high-pressure sapphire-anvil cell, itself inside an optical cryostat.

Two-pulse, stimulated and accumulated photon echoes are investigated for the first time in a highly doped crystal Tm:YAG containing 10 at.% Tm3+. The decay curves of the twopulse and stimulated photon echoes generated at 793.15 nm on the transition 3H6(1)–3H4(1) of the impurity ions are measured in the absence of an applied magnetic field and param...

В статье показан потенциал практического использования метода оптической микроскопии дорсальной кожной складки в качестве эффективной технологии диагностики живых систем. Экспериментально доказано, что даже в базовой постановке представленный метод позволяет получать большой объем полезных исследовательских данных в условиях, максимально приближенн...

Possible thermal mechanisms of photodynamic effects on biological tissues of low-intensity quasimonochromatic optical radiation in the near-IR spectral range are analyzed with the aim of developing a method of local non-invasive oxygenation.

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...

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...

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 have compared and analyzed the parameters of the Franck–Condon (FC) and Herzberg–Teller (HT) interactions, which form the fine-structure spectra of stilbene, 1,4-distyrylbenzene, and tetrafluorodistyrylbenzene—compounds that are similar in their chemical structures but differ in the length of π-conjugation and in the presence of substituents in...

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...

A comparative analysis of the parameters of the Franсk-Kondon and Herzberg-Teller interactions forming the fine-structure spectra of α, ω-tetrafluorodysterylbenzene, 1,4-distyrylbenzene and stilbene is carried out. It is shown that the introduction of fluorine substituents leads to reduce the dipole moment of the molecule, and as a result, reduces...

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...

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 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...

A theoretical model is proposed for describing the interaction of excitons with phonons and defect states in semiconductor nanocrystals. On the basis of this model, numerical simulation was performed and experimental data on the temperature dependence of the absorption and fluorescence spectra of cadmium selenide quantum dots in liquid crystal soli...

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...

Here we present investigation of the thin film with CdSe nanocrystals with the size 2.3 nm made from low-concentration toluene solution. Using fluorescent microscopy method we have found small nanocrystals ensembles up to single nanocrystals. Luminescence spectra in different parts of the test sample were registered. Analysing them we can draw a co...

In the present work the individual temperature dependences of zero-phonon spectral line widths of single tetra-tert-butylterrylene dye-molecules in polyisobutylene were measured in a broad range of low temperatures (from 20 K up to 67 K). The obtained data show the broad distribution of single molecule zero-phonon spectral line widths measured at t...

Luminescence spectra of the colloidal solution of CdSe quantum dots (in toluene) were studied in a wide range of low temperatures. Samples were synthesized in the liquid crystal matrix of cadmium octanoate (CdC8). A comparative analysis of the obtained data with previous results was performed.

New experimental data on the times of phase relaxation in the amorphous polyisobutylene doped with chromophore molecules of tetra-tert-butylterylene are obtained by the incoherent photon echo method at temperatures of 5, 7, 10, and 15 K. A comparative analysis of the results is performed and data on the widths of zero-phonon spectral lines of singl...

Cadmium selenide quantum dots chemically synthesized in a cadmium caprylate liquid crystal matrix are investigated by means of confocal microscopy. The dependence of the luminescence spectra on temperature in the range of 77.3–300 K, on quantum dot size, and on sample inhomogeneity is investigated.

Представлен обзор исследований низкотемпературной оптической дефазировки в примесных твердых средах, допированных флуоресцирующими молекулами, и сравнительный анализ дан- ных, полученных разными методами селективной лазерной спектроскопии, включая фотонное эхо и спектроскопию одиночных молекул.

The phenomenon of the zero-phonon spectral lines (ZPL), which corresponds to pure electronic transitions of impurity dye chromophore centers in solids, has already been the basis of high resolution spectroscopy for a few decades. The unique properties of the phonon-less emission in dye-doped solids (very narrow ZPLs and their extreme sensitivity to...

Quantum confinement effect and its influence on absorption and photoluminescence spectra of CdSe nanoparticles chemically synthesized in thermotropic ionic liquid crystal of cadmium octanoate are studied. It was found out that the spectral resolution grows with decrease of temperature, so it becomes possible to distinguish the band-edge luminescenc...

A convenient and efficient technique for controlling exact focusing of several noncollinear laser beams into the same point of a luminescent sample is proposed for optical photon-echo spectroscopy and four-wave mixing experiments. The technique proposed is based on a confocal luminescence microscope equipped with a sensitive multichannel detector f...

A technique for the numerical simulation of coherent optical responses of the photon echo type formed in resonance media with strong inhomogeneous broadening under the action of femtosecond laser pulses is developed. This approach is based on solving the Maxwell-Bloch equations using the finite-difference time-domain (FDTD) method without applicati...

The connection between the photonic echo formation in crystals doped by rare-earth elements and the concentration effects was studied. The application of optical echo spectroscopy in studies of garnet crystals with a high content of thulium impurity was demonstrated. By the example of activated crystals of ruby and lanthanum trifluoride, the spectr...

This paper is about the possibilities of optically dense impurity media spectroscopy by means of the incoherent photon echo. The theoretical model of the phenomenon is given. The results of experiment on incoherent photon echo in a crystal of ruby at liquid helium temperature are presented. Fiber optical delay line was used to make an incoherence o...

The possibility of using incoherent photon echo in spectroscopy of optically dense impurity media is considered. A theoretical approach to description of this phenomenon is presented. The experimental data on incoherent photon echo in ruby at liquid-helium temperature, with transport of an excitation pulse through a fiber, are reported. The spectra...

The possibility of using incoherent photon echo in spectroscopy of optically dense impurity media is considered. A theoretical approach to description of this phenomenon is presented. The experimental data on incoherent photon echo in ruby at liquid-helium temperature, with transport of an excitation pulse through a fiber, are reported. The spectra...

The results of an experimental investigation of the incoherent photon echo in ruby (with Cr3+ concentration equal to 0.16 wt%) at T = 1.7 K are presented. Optical fiber with length 3 m and diameter 100 μm was used for delivery of the first exciting pulse to a sample. The dependence of the IPE intensity on the excitation wavelength within the width...

The method of registration of weak light pulses in a mode of the photon counting is discussed. The principle of photon counting, its key points and operating circuit configuration, as well as characteristics of photomultiplier tubes and basic characteristics of the photon counting is explained. The appendix of techniques of the photon counting for...