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Project titlePhoto-thermo-chemical synthesis of nanoparticles and nanostructures with predictable of plasmonic properties

Research area 09 - ENGINEERING SCIENCES, 09-710 - New materials for nano-electronic devices

Keywordsnanoparticles, thermal diffusion, photochemical reactions, laser irradiation, laser ablation, porous glass, sol-gel films, effective medium theory, plasmon resonance, Mie theory, Maxwell-Garnett approximation, Bruggeman approximation

Annotation
The project aims to develop the scientific basis for predicting and correcting the optical properties of composite materials with nanoparticles and nanostructures in the process of their laser synthesis. The development and improvement of methods for the synthesis of nanoparticles with different plasmon properties, as well as their organization into structures, is becoming increasingly important. Such methods will be used not only to create new optical materials in the form of elements of photonics devices, but also for microanalytics, photovoltaics and optoelectronics, quantum computing systems, optical memories, etc. Particular attention is paid to the methods of element-wise fabrication of complex integrated systems in the form of chemical-biological sensors, laboratories on a chip (lab-on-chip), solar energy devices, where localization of changing the properties of nanoparticles enclosed in a common matrix or located on a single substrate becomes important. The use of laser technology in the fabrication of such elements is particularly promising. Nowadays, sufficient experience has been accumulated in the laser synthesis of nanoparticles and their organization into structures, for example, in the form of nanoantennas and metamaterials, as evidenced by a huge number of publications in high-rating journals appeared in recent years. However, most methods of laser synthesis of nanoparticles in composite materials have a significant drawback, namely, the lack of control and correction of the optical properties of the composite in the localized space during the laser exposure. For the direct laser writing of nanostructures with pronounced plasmonic properties, the lack of prediction of the optical properties of the composite becomes very critical, significantly limiting the possibilities of laser technology. That is why at the present time the search for various approaches to solving this scientific problem is extremely relevant. To solve a scientific problem, it is supposed to perform the following tasks: to conduct a theoretical and experimental study of photochemical and photothermal processes of nucleation, growth and decomposition of nanoparticles of noble metals, their oxides and halides enclosed in porous films and glasses, transparent in the visible wavelength range; to investigate the thermochemical processes of laser synthesis of noble metal nanoparticles and their oxides from the vapor-gas phase, which are formed as a result of evaporation-condensation; develop a model for predicting the optical properties of composites that change during a laser exposure process, which will be based on photo-thermo-chemical mechanisms for the synthesis of nanoparticles and nanostructures with plasmon properties. The scientific novelty of the project lies in proposing a new solution for predicting the optical properties of nanostructures, which will be based on an integrated approach to the theoretical description and experimental substantiation of the mechanisms of nucleation, growth and destruction of nanoparticles in composites. The knowledge gained during the project will be applied to the implementation of the technological process with the possibility of correcting the plasmon properties of nanoparticles and, consequently, the optical properties of the composite. In future, the possibility of such prediction will open up new perspectives for the development of machine learning algorithms in laser recording technologies for meta-surfaces and functional materials, elements for photonics devices and microanalytics, when laser processing conditions are corrected during recording without operator intervention. To this end, the model representations will be necessary to associate the laser processing conditions with the optical characteristics of the composite itself, which can be integrated into the software with the possibility of implementing the feedback. The relevance of developing such cyber-physical systems (Cyber-Physical Systems) of various levels and purposes is difficult to overestimate in the modern world. Such systems, creating a close relationship and coordination between computational resources (output parameters in the form of simulation results) and physical resources (input parameters in the form of experimental data), ensure the harmonious operation of automated systems. In such systems, a continuous cycle of data exchange in the form of direct-feedback is implemented, where changes in the physical system begin to influence the model's calculations and vice versa. Thus, the cyber-physical system of direct laser recording of nanostructures with full automation of the process can be a promising development of the results of research carried out in the project. It should be noted that there are still no any model representations that comprehensively connect the mechanisms of photo-thermo-chemical synthesis of nanoparticles and their properties with the optical characteristics of the composite and the conditions of laser irradiation. Separate and unrelated theories and models describing the photochemical synthesis of nanoparticles, the optical properties of the composite with nanoparticles, the absorption of laser radiation and the heating of the material do not fully explain the results of many experiments. Currently, research teams around the world are actively working on the possibility of predicting the plasmonic properties of nanoparticles that change under the action of laser radiation. In particular, this problem is under consideration by Hubert Curiein Laboratory of the French National Center for Scientific Research of the University of Jeanne Monnet (F. Vocanson, N. Destouches and T. Itina), with whom the authors of this project closely collaborate for a couple of years. In recent years, the authors of the project have carried out numerous experimental studies on laser-induced formation of nanoparticles enclosed in porous glass and sol-gel films, their organization into structures, as well as on the laser synthesis of nanoparticles as a result of ablation of the surface of precious and non-ferrous metals with the subsequent formation of coatings plasmon resonance. In addition, participation in the project of Professor T. Itina, working at ITMO University as part of a program to attract leading world scientists to Russian institutions of higher education, that will create a new independent group of young researchers, who will participate in the international collaborations and solve world-class scientific problems. The results of theoretical and experimental studies obtained in the framework of the project will have a high world level, since the study of the mechanisms of synthesis of metal nanoparticles and nanocrystals with pronounced plasmonic properties, periodic nanostructures in the form of metamaterials and multilayer films with nano-objects are relevant.

Expected results
The main expected result will be obtaining new knowledge about the mechanisms of laser synthesis of metal nanoparticles in composites, which will become the basis for developing a model describing changes in the characteristics of nanoparticles, their plasmon properties and, consequently, the optical characteristics of the composite. It will be possible to predict the optical properties of the composite as they change during laser irradiation, which is important for the development of automation algorithms for the manufacture of various nanostructures, metamaterials, photonics and microanalytics elements. In the case of practical application of the developed model for creating cyber-physical systems for direct laser recording of nanostructures, it will be possible to reduce the cost of manufacturing photonic elements, which will ensure their mass production. The possibilities of predicting the size, shape, concentration and dispersion scatter of nanoparticles in a transparent matrix will be revealed when exposed to laser pulses with short and ultrashort duration (from 500 ns to 150 fs), as well as continuous radiation. The efficiency of using photochemical reactions for the synthesis of nanoparticles during exposure to UV radiation, as well as the effectiveness of using IR laser radiation for thermal diffusion synthesis of nanoparticles will be determined. A comparative analysis of the modification of the structure of the porous matrix and the properties of nanostructures arising under the action of near-infrared (1.07 μm) and far-infrared (10.6 μm) radiation will be carried out. In the first case, radiation is absorbed only on nanoparticles, in the second case, laser radiation is absorbed by the matrix. The features of the thermochemical synthesis of metal nanoparticles and their oxides in the process of evaporation-condensation from the vapor-gas phase resulting from laser ablation of the target will be investigated. In this case, approaches to laser correction of the optical properties of noble metals with nanoparticles will be determined. As a result, a complex model will be developed to predict the optical properties of composites with nanoparticles that change their properties during laser irradiation. To predict the optical properties of the composite, an effective medium theory will be applied, taking into account the polarization properties of light and adapted for porous transparent materials containing nanoparticles, as well as nanoparticle coatings. The model being developed will combine elements of the effective medium theory in the Maxwell-Garnett and Burggemann approximations, as well as models of diffusion-controlled growth of nanoparticles and the thermophysical equations for heating the material in the laser-impact zone. This project will provide the criteria for domestic developers of laser systems and complexes that are suitable for precision laser micro- and nano-processing of composite materials. The physical bases of the studied processes obtained in the course of the project implementation will allow to proceed to the introduction of methods of laser processing of composite materials in production. There will be an opportunity to create new science-based work positions. The complex modeling approaches proposed in the project will open up prospects for developing machine learning algorithms in laser recording technologies for meta-surfaces and functional materials, elements for photonics devices and micro-analysis. Thus, the practical use of the expected results of the project will have a positive impact on the economy as a whole.

Annotation of the results obtained in 2021
All planned studies for the third year of the project were successfully carried out. The effect of pulsed radiation with wavelengths of 343 nm and 515 nm on the silver nanoparticles in a TiO2 thin film was studied. It is shown that the use of a wavelength of 343 nm had little effect on the size of nanoparticles, since such radiation fell into the intrinsic absorption region of the film and is weakly absorbed by nanoparticles. In turn, under the influence of visible radiation falling into the plasmon resonance peak, the size of the nanoparticles noticeably increased, while the dependence of this parameter on the radiation energy density was more pronounced. The differences in the mechanism of modification depending on the wavelength are described. In the case of 343 nm, the size and concentration of nanoparticles did not affect the absorption of the sample; heating of the particles was initiated by heat diffusion from the TiO2 matrix. The opposite situation was observed at a wavelength of 515 nm. The TiO2 film itself was heated by nanoparticles that absorbed the radiation. Due to this, the use of the second harmonic made it possible to tune the position of the plasmon resonance peak more accurately. Additionally, the band gap of the material was determined. A simulation of a heat source that occurs under the action of femtosecond laser pulses with wavelengths of 343 nm and 515 nm was carried out, considering the accumulation of heat. As a result of the simulation, the temperatures in the laser impact zone were estimated, including the shape of the heat source in the film. The maximum temperature after the laser pulse was always practically the same and did not exceed the evaporation temperature of the material (2973 K), in contrast to the temperature to which the film cooled by the beginning of the next pulse. Thus, the rate of heat accumulation in the region of laser action depended, among other things, on the thermophysical characteristics of the film (its cooling rate). It was shown that continuous radiation with a wavelength outside the region of the plasmon resonance peak also makes it possible to tune it over a wide range. When ZnO was exposed to radiation with a wavelength of 405 nm, thin films with silver nanoparticles with power densities q=0.16-202 MW/m2, the peak of the plasmon resonance successively shifted from 580 nm to 480 nm. In addition, the influence of the initial characteristics of the film the initial annealing temperature, on the result of laser processing is shown. The effect of laser radiation on the band gap of the material, the value of which decreased after exposure, was studied. Using the theory of effective media, the volume fraction of nanoparticles, their chemical composition, and the average statistical size were estimated. In the case of the TiO2 film, both wavelengths led to an increase in the volume fraction of nanoparticles. When using a wavelength of 515 nm, the shift of the plasmon resonance peak to the IR region was associated with an increase in the percentage of silver oxide, the increase in the size of nanoparticles, their concentration, and the proportion of silver oxide was more significant than at 343 nm. In the case of AlZnO films, the size of nanoparticles decreased by an order of magnitude. An increase in power density led to a decrease in the volume fraction of silver, a change in speed had little effect on it, but this affected the fraction of silver oxide. The optical properties of nanogratings on the AlZnO thin films with silver nanoparticles were studied. The dependence of the spectral characteristics of such a structured material on polarization and the angle of incidence of radiation is presented. It has been shown that periodic nanostructures can be used to enhance the rhodamine luminescence signal. Using the theory of effective media, the spectral properties of the material are simulated, and a satisfactory agreement between the experimental and calculated values is shown. A technology for color identification of precious metals due to plasmon resonance in laser-induced nanoparticles was developed. A base for silver has been compiled, which relates the laser-induced color and the parameters of laser exposure to radiation with a pulse duration of 14 ns and a pulse repetition rate of 75 kHz. The parameters of nanoparticles formed by laser ablation, their size and concentration have been studied. An algorithm for sample pretreatment, color label formation, and identification is presented. The chemical resistance of labels was studied when applying a protective coating. Based on the project materials, 1 article was published in 2022 with acknowledgments to the Russian Science Foundation, in journal included in the scientometric databases "Web of Science" and Scopus.

Publications

1. S lectrical and Optical Properties of Laser-Induced Structural Modifications in PbSe Films -, T. 323. C. 132605 (year - 2022)

2. Sergeev M. M., Gresko V. R., Andreeva Y. M., Sokura L. A., Shirshneva-Vaschenko E. V., Itina T. E., Varygin G. V. Sergeev M. M., Gresko V. R., Andreeva Y. M., Sokura L. A., Shirshneva-Vaschenko E. V., Itina T. E., Varygin G. V. Precise laser-induced local modification of AZO:Ag films and their optical properties Precise laser-induced local modification of AZO:Ag films and their optical properties er Technology Optics & Laser Technology, 151, 108059 (year - 2022) https://doi.org/10.1016/j.optlastec.2022.108059

3. Varlamov P.V., Sergeev M.M., Zakoldaev R.A., Grigoryev E.A. Femtosecond wavelength influence on TiO2:Ag film spectral changes: Comparative study Materials Letters, T. 323. C. 132605 (year - 2022) https://doi.org/10.1016/j.matlet.2022.132605

Annotation of the results obtained in 2019
In the first year of the project, research was carried out and all work was completed according to the approved plan. First, the physico-mathematical model is developed to describe optical characteristics of applied photonic materials utilized in the project. In particular, the simulation of an effective medium to calculate the optical properties of dielectric solid materials with embedded nanoparticles produced by photo-thermo-chemical synthesis. An electronic structure, size and concentration of a secondary phase is connected with the optical properties of the material through an algorithm suggested. However, physico-chemical properties of the samples were different that asked us to consider all possible mechanisms of laser interaction with both secondary phase and nanoporous framework. The algorithm includes the model of the diffusive controlled nanoparticles growth to provide a real-time control during laser processing. The model working ability was repetitively proved by its comparison to experimental results obtained in this project. The research involved laser processing of nanoporous materials (SiO2 and TiO2) with embedded different nanoparticles: Ag, Ag2O, Au, AgCl, AgBr и AgI. For example, various lasers from experimental femtosecond systems to commercially-available laser modules were utilized to demonstrate and investigate the peculiarities of Ag nanoparticles size and concentration change in nanoporous framework under the irradiation. The laser parameters, experimental conditions were determined and described for all the cases. Non-contact, spectral characterization of the samples and fabricated structures was conducted before and after laser processing. A gradual investigation of a bulk composite materials laser-induced modification was carried out including the following steps: (i) the sample transparency change registration during laser irradiation; (ii) a rapid analysis of optical constants of the secondary phase during irradiation; (iii) the simulation of spectral characteristics of the fabricated regions with the complex structure and chemical composition. That helps to control the optical properties of the composite material during laser irradiation. Let’s note here that semi-empirical methods are utilized usually for such a task. Photonic materials 3D structuring forwards us to consider the potential of photonic elements fabrication with unique optical properties based on the model and methods developed. Thus, the model experiment has been realized to investigate the process of the refractive index change inside initial porous glass, which is a base material of the composite. After irradiation with femtosecond laser pulses, the manageable change in the refractive index was realized and core-cladding waveguides were produced. Thermo-chemical synthesis of nanoparticles during silver evaporation-condensation by nanosecond laser ablation was investigated in details including SEM, TEM, spectral investigation. The mechanism of a color palette formation was studied with the help of comparison of an experimental data with modeling representation. The practical significance is the color laser marking of a noble metal with high contrast. The ability to expand the color palette while correcting the position the wavelength peak was also shown. The following development of the theoretical basis of a laser-induced metal coloration significantly increases the technology quality and expends its science and industrial ability. The results obtained during the first stage of the project are an integral part of the next project stage. In particular, the model will be supported with thermophysical plugin to estimate the thermal fields, which activate the nanoparticles growing process. Nanograting formation in the laser processing zone will be taken into the optical part of the model. The experimental and theoretical studies will be continued with nanoporous films (SiO2 and TiO2) soaked with Ag nanoparticles. The model and methods developed are universal that allows to apply them with new materials. One of them is a sol-gel semiconductor films (AlZnO), which are widely applied in photonic, photovoltaicsб micro-analytic tasks. There are 2 papers have been published (Web of Science and/or Scopus) in 2020 based on the results obtained. The papers acknowledge the financial support from Russian Scientific Foundation.

Publications

1. A. Krivonosov, D. Zuev, S. Kaputkina, V. Mikhailovskii, E. Egorova, E. Ageev, G. Odintsova Evolution of size distribution of Si nanoparticles produced by pulsed laser ablation in water Optical and Quantum Electronics, 3, 52, 1-7 (year - 2020) https://doi.org/10.1007/s11082-020-02274-z

2. L. Zhong, R.A. Zakoldaev, M.M. Sergeev, V.P. Veiko, L. Zhengyan Porous glass density tailoring by femtosecond laser pulses Optical and Quantum Electronics, 1, 52, 1-8. (year - 2020) https://doi.org/10.1007/s11082-019-2163-7

Annotation of the results obtained in 2020
All planned studies for the second year of the project were successfully carried out. The mechanisms of photothermal formation and destruction of silver nanoparticles in films of titanium dioxide (TiO2) and zinc oxide containing 0.5% aluminum (AlZnO) were studied. To modify the structure of films with nanoparticles, continuous-wave laser radiation with a wavelength of 405 nm and femtosecond laser pulses with wavelengths of 515 and 343 nm were used. The influence of the wavelength and the duration of laser exposure on the character of changes in the optical properties was investigated. The exposure results of the continuous radiation and a series of femtosecond pulses (250 fs) with a high frequency (500 kHz) providing the effect of heat accumulation were compared. Thermal densification, melting, and phase transitions in the matrix upon laser irradiation were observed in all cases, as well as a change in the size of silver nanoparticles and their migration from the heated zone. The best result was achieved using a laser with a wavelength of 515 nm, i.e. under conditions of direct photothermal action on nanoparticles. In this case, absorbed energy by nanoparticles was transferred to the matrix due to heat transfer, and the matrix, retaining the accumulated heat, did not allow nanoparticles to cool down quickly. The use of the 343 nm wavelength also led to a change in the optical properties of the film, however, these changes were poorly expressed. Here, the absorption of irradiation occurred already on the matrix itself, which heated nanoparticles, activating thermal diffusion growth or destruction. In the case of such an indirect photothermal influence on nanoparticles, the possibility of a controlled change in their size and concentration was significantly complicated. The result of the exposure with continuous and femtosecond radiation on the film turned out to be similar in the mechanism of structure modification. In the case of continuous radiation, the maximum temperature and heating rate of the film were lower. Some results of the study on laser exposure of TiO2: Ag films with continuous radiation are given in the work: https://cyberleninka.ru/article/n/issledovanie-vliyaniya-parametrov-lazernoy-obrabotki-na-spektralnye-harakteristiki-serebrosoderzhaschih-plenok-dioksida-titana The next study considers laser exposure on porous silicate glasses containing silver and copper halides. The study of the mechanisms of structural modification and optical properties of such materials in combination with the simulation based on effective medium theory, which takes into account the complex composition and properties of the samples, made it possible to carry out laser formation of micro-optical elements with plasmonic properties within tuning over these properties in real time. The research results are given in the work: https://www.mdpi.com/2079-4991/10/6/1131 The mechanism of thermal densification in porous glasses under femtosecond laser exposure was studied, and two types of waveguides were investigated: gradient and core-cladding. A thermophysical model was proposed to describe the formation mechanism of waveguides in the bulk of porous glasses. Estimates of the maximum temperature and its gradient in the area of the laser beam waist were given. The results of calculations and description of waveguides in porous glass are given in the work: http://www.jlps.gr.jp/jlmn/uploads/20-058.pdf We studied the features of laser processing of nanogratings with a period of 0.4 - 0.7 μm on surfaces of sol-gel films with silver nanoparticles of the following types: SiO2: Ag, TiO2: Ag, AlZnO: Ag. A picosecond Nd:YAG laser at a wavelength of 355 nm were used for gratings formation. Laser pulses were converted into two-beam interference using a phase grating and a confocal optical system. The mechanisms of nanograting formation in the regime of film melting and evaporation were investigated. Thermophysical model was proposed that describes the heating and cooling of the film from an interference field with an ultrashort pulse duration. A modeling based on effective media theory is proposed to describe the optical characteristics of relief nanogratings on a film with nanoparticles. A description of the thermophysical model of the formation of nanogratings and the results of its application are given in the work: http://www.jlps.gr.jp/jlmn/uploads/20-064.pdf The possibility of correcting and stabilizing the optical characteristics of samples with silver surface in color laser marking was considered. Coloration of the silver surface as a result of exposure by nanosecond laser pulses is explained by the formation of silver nanoparticles and their deposition in the irradiated zone. The color palette is determined by the composition, size, shape and concentration of silver nanoparticles and depends on the regimes of laser processing. Particles that do not adhere to the surface of a silver target are removed from it during storage and use, which leads to degradation of color images over time. For this reason, studies were carried out on the influence of an aggressive environment on the color characteristics of the treated silver surface, as well as possible ways to stabilize the color characteristics of the irradiated surface. For protection, we used special polymer. The correction of the color characteristics of silver after laser marking was carried out by heating in an oven. At temperatures from 200 to 550 C, the diffusion growth of nanoparticles, their oxidation, or decomposition with a complete loss of plasmonic properties took place. The modification mechanism silver nanoparticles was determined by the temperature and duration of heating in the oven. The description of the mechanism of color formation on the silver surface as a result of laser processing is given in the work: https://www.scientific.net/MSF.1022.35 Based on the project materials, 4 articles were published in 2021 with acknowledgments to the Russian Science Foundation, in journals included in the scientometric databases "Web of Science" and Scopus, and 1 article in a journal from the RSCI list.

Publications

1. Mikhailova J.V., Lijing Z., Ostanin A.A., Sergeev M.M., Zakoldaev R.A. Gradient and Core-Cladding Waveguides Fabrication in Porous Glass Journal of Laser Micro/Nanoengineering, T. 15, № 3. (year - 2020) https://doi.org/10.2961/jlmn.2020.03.2016

2. P.V. Varlamov, J.V. Mikhailova, Y.M. Andreeva, M.M. Sergeev Исследование влияния параметров лазерной обработки на спектральные характеристики серебросодержащих пленок диоксида титана НАУЧНО-ТЕХНИЧЕСКИЙ ВЕСТНИК ИНФОРМАЦИОННЫХ ТЕХНОЛОГИЙ, МЕХАНИКИ И ОПТИКИ, том 20, №5, стр. 634 - 641 (year - 2020) https://doi.org/10.17586/2226-1494-2020-20-5-634-641

3. Sergeev M.M., Zakoldaev R.A., Gresko V.R. Effective Time of Nanogratings Formation on Sol-Gel Films by Two-Beam Laser Interference Journal of Laser Micro/Nanoengineering, том 15, выпуск 3, с. 1-6 (year - 2020) https://doi.org/10.2961/jlmn.2020.03.2010

4. Sergeev M.M., Zakoldaev R.A., Itina T.E., Varlamov P.V., Kostyuk G.K. Real-Time Analysis of Laser-Induced Plasmon Tuning in Nanoporous Glass Composite Nanomaterials, том 10, выпуск 6, с. 1131 (year - 2020) https://doi.org/10.3390/nano10061131

5. V.V. Romanov, T-A Nguyen, N.N. Shchedrina, D.S. Lutoshina, V.Yu. Mikhailovskii, D.V. Danilov, M.M. Sergeev, G.V. Odintsova Color identification mark by laser processing of silver surface Journal of Physics: Conference Series, Vol. 1022. P. 35-41 (year - 2021) https://doi.org/10.4028/www.scientific.net/MSF.1022.35

6. - Ученые Университета ИТМО разработали способ создания элементов плазмоники ITMO.NEWS, Maksim M. Sergeev, Roman A. Zakoldaev, Tatiana E. Itina, Pavel V. Varlamov, Galina K. Kostyuk. Real-Time Analysis of Laser-Induced Plasmon Tuning in Nanoporous Glass Composite. Nanomaterials, 2020/10.3390/nano10061131 (year - )