Paper sheet materials and written compositions are complex multi-component mixtures, including dyes, solvents and resins, preservatives, and antioxidants, i.e., complex organic mixtures that change over time. Technical examination of materials and documents is in demand in the judicial and archival industry. Determining the actual date of appearance of a particular inscription on a sheet of paper is one of the most important and complex expert tasks. The task is divided into two components: analysis of the processes of temporary degradation of paper pulp and processes of temporary degradation of organic writing materials.

Introduction The method of laser deposition of metal nanoparticles from a solution has been considered a promising approach for various applications in microelectronics since the end of the 20th century. Two new patents describe this promising method. They concern microelectronic applications. Meanwhile, as it turns out, the possibilities of the method are much broader. Laser-assisted liquid deposition is characterized by very low process rates (millimeters per hour) and high electrical resistance-2-5 orders of magnitude higher than the original materials. Therefore, we focused on another side effect of the process: the active release of gas phases of unsaturated hydrocarbons and hydrogen during the reaction. The goal was to explore the potential use of the effect of organic catalysis, which accompanies laser reactions in a liquid medium, in hydrogen energy and controlled organic synthesis.Methods The experiments were conducted with respect to water-organic alcohol mixtures of glycerol and isopropanol. V, Zr, Pb, Mo, Zn, and Nb were used as the tested nanocatalysts. The results of the process were monitored by liquid and gas phase GCMS, electron microscopy, optical microscopy and VX analysis. The competition of two processes was studied: laser deposition and laser ablation.Results There was largely confirmed the assumptions regarding the high catalytic activity of metal nanoparticles formed as a result of two competing reactions: ablation and deposition occurring simultaneously in the laser beam focus in the solution. These reactions are dehydrogenation of saturated hydrocarbons and water, resulting in the formation of hydrogen and unsaturated hydrocarbons. Another result of the reaction is the deposition of pure reduced metal layers on the substrate in the reaction zone.Discussion Some chemical reactions leading to this result have been deciphered. Firstly, these are reactions of formation of unsaturated hydrocarbons under the action of high energy flow on the surface. Then reactions of elongation of carbon chain at the place of formation of double bond can proceed. Complexation in solution with participation of organic compounds leads to autocatalytic reactions of precipitation of pure metals, including gold.Conclusion These arise due to an ability in liquid and precipitation reactions. This opens up another potential application for the process: refining trace amounts of precious metals, as demonstrated with gold. Both processes are environmentally friendly, which enhances the potential positive impact of their application.

Abstract: The chemical processes that occur during the surface degradation of document paper under the influence of external factors were studied by Raman spectroscopy. The possibility of comparing the same processes occurring on clean free paper and under printed text toner letters is of interest. It is assumed that the transformation of cellulose can occur at different rates in the areas of paper exposed to direct atmospheric and light exposure and in the areas containing an intermediate layer of the toner. The most stable temporal changes occur in the region of C–C–C and C– C–O vibrations of glycosidic rings in the short-wavelength region of the Raman spectrum. Background: The main areas of research in the field of document dating, mainly focused on chromatographic methods. These methods are based on studying the dynamics of evaporation of volatile ink components. There is also a variety of chromatography techniques, including gas chromatography, ion chromatography, high performance liquid chromatography, thin layer chromatography and gas chromatography-mass spectrometry. This indicates the wide range of approaches and techniques used to determine the age of written materials. However, all these methods are used mainly during the first two years after writing the document details, which does not allow examining documents that are more than two years old. Methods: Raman spectroscopy was used as the main research method. The object of the study was sheets of white A4 paper with printed text printed on them, produced on a laser printer. The subject of the study was areas of paper free of text, as well as areas of paper under toner. The integrated fluorescence of a paper optical brightener based on stilbene was studied in the wavelength range of 400–500 nm. Also, all objects were studied using optical microscopy. Results: The comparison of peak intensity values averaged over 10 brands over the years made it possible to reveal the following regularities: – the ratio of peaks in the paper spectra from which the toner was removed is greater than in the blank paper spectra, and the difference becomes less noticeable as the age of the paper decreases. The ratio of the intensity of the 330 cm-1 peak to the intensity of the 1603 cm-1 peak: the older the document becomes, the lower the average ratios of these peaks in both the blank paper spectra and in the spectra of paper from which the toner has been removed. –the intensity of the peak in the region of 280 cm-1 and 1 086 cm-1 of the Raman shift increases with decreasing the age of the toner-free paper.– a gradual increase in the intensity of the 380 cm-1 peak is observed when comparing the paper samples from which the toner was removed for 2016, 2018, 2020, and 2022. Regularity was also found in the change in the ratio of the average statistical values of the peak at 280 cm-1 in the spectra of the paper under the toner to a similar peak in the spectra of the paper free from text: the value of this ratio decreases with decreasing the paper age. At the same time, the paper fluorescence signal is an informative parameter that makes it possible to establish some facts from the document’s history. With artificial document aging, a significant broadening of the dispersion region and the appearance of its “splitting” into two or three strata are observed in the distribution of the fluorescence signal level of a paper sheet relative to the average value. The average fluorescence signal of a naturally aged sheet decreases with the age of the document. Conclusion: As a result of research, it has been established that Raman spectroscopy can be successfully used as a method for dating documents. When comparing the degree of degradation of the surface of open areas of paper and areas protected by toner of printed text, different effects of external factors on these areas were established, leading to different rates of degradation processes. The use of Raman peak intensity ratios for paper components in exposed areas compared to peaks under printed text further expands the methodology. The emphasis on spectral methods, in particular fluorescence signal distribution and Raman spectroscopy, to detect surface changes is well justified. It demonstrates a holistic approach to document analysis, taking into account both the chemical changes observed using Raman spectroscopy and the fluorescence signal distribution that may indicate signs of artificial aging through light exposure. This combination of methods appears to be reliable for assessing the age of documents and can make significant contributions to the field of forensic document examination.

Introduction: The catalytic activity of metallic nanomaterials depends on their surface morphology. A widely known method is the laser synthesis of metal nanostructures by depositing on dielectric surfaces from aqueous solutions containing metal complexes. The article analyzes the factors that favor the production of conductive, catalytic, and sensory-active deposits by laser method. It is shown that the two main factors is the presence of a large number of charged defects on heterophase surfaces and the structure of metal-containing complexes in solution. This is typical for mono- and bimetallic alloys, the components of which interact with the laser beams according to the autocatalytic type. Using the example of laser deposition from solutions of Co, Ni, Fe, Zn, and Ag salts with homo- and heterophase dielectrics, the sensory and catalytic properties of the deposits are compared by impedance spectroscopy and voltammetry. It has been shown that heterophase precipitation significantly enhances the catalysis response. Background: It is known that the highest catalytic activity exhibits nanostructured and highly porous materials with a large specific surface area and materials containing surface heterogeneity in the form of charged acid-base centers. Such materials are necessary for the creation of new catalysts for organic synthesis and for the creation of new sensor materials for enzyme-free microbiosensors. Active development of new methods for the synthesis of such materials is underway. But not all of them give the expected result. Methods: Laser synthesis methods have the best prospects, including the method of laser-induced metal deposition. This is the laser synthesis of metal nanostructures by depositing dielectric surfaces from aqueous solutions containing metal complexes. Results: Аrticle analyzes the factors that favor the production of conductive, catalytic, and sensory-active deposits by laser method. It is shown that the two main factors are the presence of a large number of charged defects on heterophase surfaces and the structure of a metal-contained complex in solution. This is typical for mono- and bimetallic alloys, the components of which interact with the laser beam according to the autocatalytic type. Using the example of laser deposition from solutions of Co, Ni, Fe, Zn, and Ag salts with homo- and heterophase dielectrics, the sensory and catalytic properties of the deposits are compared by impedance spectroscopy and voltammetry. Conclusion: It has been shown that heterophase precipitation significantly enhances the catalysis response. It is shown that the laser deposition reaction has an autocatalytic mechanism in a dynamic mode. The results of autocatalysis can be used in a stationary mode to create a microbiosensor for glucose, as well as to create a technology for laser refining rare metals and hydrogen energy in a dynamic mode.

The chemical processes that occur during the surface degradation of document paper under the influence of external factors were studied by Raman spectroscopy. The possibility of comparing the same processes occurring on clean free paper and under printed text toner letters is of interest. It is assumed that the transformation of cellulose can occur at different rates in the areas of paper exposed to direct atmospheric and light exposure and in the areas containing an intermediate layer of the toner. The most stable temporal changes occur in the region of C-C-C and C-C-O vibrations of glycosidic rings in the short-wavelength region of the Raman spectrum.Background The main areas of research in the field of document dating, mainly focused on chromatographic methods. These methods are based on studying the dynamics of evaporation of volatile ink components. There is also a variety of chromatography techniques, including gas chromatography, ion chromatography, high performance liquid chromatography, thin layer chromatography and gas chromatography-mass spectrometry. This indicates the wide range of approaches and techniques used to determine the age of written materials. However, all these methods are used mainly during the first two years after writing the document details, which does not allow examining documents that are more than two years old.Methods Raman spectroscopy was used as the main research method. The object of the study was sheets of white A4 paper with printed text printed on them, produced on a laser printer. The subject of the study was areas of paper free of text, as well as areas of paper under toner. The integrated fluorescence of a paper optical brightener based on stilbene was studied in the wavelength range of 400-500 nm. Also, all objects were studied using optical microscopy.Results The comparison of peak intensity values averaged over 10 brands over the years made it possible to reveal the following regularities: - the ratio of peaks in the paper spectra from which the toner was removed is greater than in the blank paper spectra, and the difference becomes less noticeable as the age of the paper decreases. The ratio of the intensity of the 330 cm-1 peak to the intensity of the 1603 cm-1 peak: the older the document becomes, the lower the average ratios of these peaks in both the blank paper spectra and in the spectra of paper from which the toner has been removed. -the intensity of the peak in the region of 280 cm-1 and 1 086 cm-1 of the Raman shift increases with decreasing the age of the toner-free paper.- a gradual increase in the intensity of the 380 cm-1 peak is observed when comparing the paper samples from which the toner was removed for 2016, 2018, 2020, and 2022. Regularity was also found in the change in the ratio of the average statistical values of the peak at 280 cm-1 in the spectra of the paper under the toner to a similar peak in the spectra of the paper free from text: the value of this ratio decreases with decreasing the paper age. At the same time, the paper fluorescence signal is an informative parameter that makes it possible to establish some facts from the document's history. With artificial document aging, a significant broadening of the dispersion region and the appearance of its "splitting" into two or three strata are observed in the distribution of the fluorescence signal level of a paper sheet relative to the average value. The average fluorescence signal of a naturally aged sheet decreases with the age of the document. Conclusion As a result of research, it has been established that Raman spectroscopy can be successfully used as a method for dating documents. When comparing the degree of degradation of the surface of open areas of paper and areas protected by toner of printed text, different effects of external factors on these areas were established, leading to different rates of degradation processes. The use of Raman peak intensity ratios for paper components in exposed areas compared to peaks under printed text further expands the methodology. The emphasis on spectral methods, in particular fluorescence signal distribution and Raman spectroscopy, to detect surface changes is well justified. It demonstrates a holistic approach to document analysis, taking into account both the chemical changes observed using Raman spectroscopy and the fluorescence signal distribution that may indicate signs of artificial aging through light exposure. This combination of methods appears to be reliable for assessing the age of documents and can make significant contributions to the field of forensic document examination.

Background Determination of diagnostically significant components of biological materials using enzyme-free microscopic sensors is an urgent scientific task, which is being worked on by a significant number of scientific groups in the world. This is due to the fact that microscopic sensor-active tracks on inert surfaces can be obtained without preliminary manufacturing of precision templates. Methods Laser Induced Chemical Liquid Phase Deposition (LCLD) is a laser technology that allows the deposition of microsized conductive tracks from aqueous solutions of transition metal compounds at the focus of a laser beam. These tracks can be formed by one or two metals at the same time. The possibility of obtaining complexes in solution in which two different metals interact with one common coordination sphere of the ligand is of particular interest. The structure of such complexes is still insufficiently studied. Results The present study supplements the missing information on tartaric acid complexes, which can simultaneously coordinate two metals, for example, copper, nickel, silver, iron, and cobalt. Heterophase LCLD demonstrates high sensory activity in the electrochemical oxidation/reduction of glucose and hydrogen peroxide. Bimetallic deposits can be obtained in two ways. The first method consists of successive precipitation from a solution containing an ion of one metal, then another on top of the first. The second way is to create a solution in which two metals and one ligand are simultaneously present. Laser deposition is carried out in one stage. In practice, the possibility of the second method is not always realized. Conclusion In the present work, the basic principles of the formation of heterophase bimetallic sensor-sensitive porous material with a highly developed surface under the action of laser radiation have been analyzed, and new reference data have been accumulated on the structure of tartrate complexes containing two metals.

The use of laser methods for synthesizing new materials for non-enzymatic electrochemical microsensors for express analysis of biological fluids is a promising scientific question. Laser-induced chemical liquid phase deposition is the laser deposition of invisible miniature bimetallic deposits from aqueous solutions of salts and complexes of transition metals. Bimetallic complexes containing two transition metal cations in the shell of one ligand are of increased interest. There is an information gap in this area even for ligands such as tartrate. The studies carried out make it possible to obtain new information on the structure of bimetallic tartaric complexes in solutions containing simultaneously copper, nickel, silver, iron, and cobalt.

When establishing the age of a document using spectral methods, the result is influenced not only by the storage conditions, but also by the methods of measuring the spectra and mathematical processing of the results. This work analyzes the influence the modes of measuring Raman spectra have on the result of measuring the writing composition spec-tra. The analysis area includes the correlation coefficients of the full spectral matrices as a criterion for the reliability of the determination date. The influence of focusing accuracy, correctness of subtraction of the baseline, sample irradiation time, and varying the number of repetitions is investigated. In the study, chemometric tools for the analysis of Raman spectra were also applied. The influence of mathematical spectra processing shows that the components PC4, P5, and PC6 are most closely related to the shelf life, although they do not make the maximum contribution to the variance in the system. Taking into account all the requirements for measuring spectra, the PCA method applied to the Raman spectra of writing compositions allows clustering samples by manufacturer’s brands and by the sample shelf life.

Dating an inscription on a sheet of paper by analyzing the dye is one of the most important and complex forensic tasks. To date, the task of analyzing the limitation of document details has not been fully resolved. Currently, the main research trend in the field of dating is the use of various chromatography methods. They are based on the study of the evaporation dynamics of volatile ink components. Basically, such methods are used within 2 years of the stroke of the writing composition. In addition to traditional gas chromatography, researchers use all known separation methods to determine the age, including ion chromatography, high-performance liquid chromatography, thin-layer chromatography, and gas chromatography-mass spectrometry. The review analyzes the most authoritative European studies in this area and discusses the reasons behind the limitations of chromatographic methods. An alternative to chromatographic studies of volatile components are spectral methods for the analysis of dyes. The most interesting works carried out by the methods of mass spectrometry, microspectrophotometry, Raman spectroscopy, diffusion of luminescence in the near-infrared and visible regions, laser-induced breakdown spectroscopy, Fourier-transform infrared spectroscopy, etc. are described. Despite a number of successful works in this area, the desired result has also not yet been achieved in terms of the accuracy and reliability of the results. The advantages and disadvantages of the methods are analyzed. Modern researchers are beginning to actively use new methods of mathematical processing of digital signal arrays. Examples of the use of chemometric data processing, including principal component analysis, are presented.

Azobenzene/tetraethyl ammonium photochromic ligands (ATPLs) are photoactive compounds with a large variety of photopharmacological applications such as nociception control or vision restoration. Absorption band maximum and lifetime of the less stable isomer are important characteristics that determine the applicability of ATPLs. Substituents allow to adjust these characteristics in a range limited by the azobenzene/tetraethyl ammonium scaffold. The aim of the current study is to find the scope and limitations for the design of ATPLs with specific spectral and kinetic properties by introducing para substituents with different electronic effects. To perform this task we synthesized ATPLs with various electron acceptor and electron donor functional groups and studied their spectral and kinetic properties using flash photolysis and conventional spectroscopy techniques as well as quantum chemical modeling. As a result, we obtained diagrams that describe correlations between spectral and kinetic properties of ATPLs (absorption maxima of E and Z isomers of ATPLs, the thermal lifetime of their Z form) and both the electronic effect of substituents described by Hammett constants and structural parameters obtained from quantum chemical calculations. The provided results can be used for the design of ATPLs with properties that are optimal for photopharmacological applications.

The paper describes the results of using Raman spectroscopy to study the canvases of Russian avant-garde artists. The study aimed to identify stable signs of paints for the recognition of counterfeits. The subject of the research was zinc white as a component of paints used by the 20th-century Russian avant-garde. Temporal changes occurring with them are due to chemical reactions of organic paint components with whites and with each other. The study shows that Raman spectroscopy is the most sensitive method for detecting ZnO time markers. Its results are compared with the results of pyrolysis-gas chromatography, mass spectrometry, and X-ray analysis of paints from paintings from the Russian avant-garde of the early, middle, and late twentieth century. The study results demonstrate that the paint compositions of the early and late 20th Century have significant similarities. The result of their aging is the appearance of products of thermal desorption and pyrolysis in the form of a homologous series of alcohols and aromatic hydrocarbons formed during the destruction and oxidation of oleic, linoleic, linolenic, palmitic, stearic acids, and/or azelaic acid. These acids are found in flaxseed oil. Zinc white of the early 20th century contains significant additions of gypsum. The composition of the components of midcentury paints is much less diverse. Genuine paintings contain homologous series of fatty acids sorbed on zinc oxide. The paper analyzes historical reasons for this phenomenon. The research shows that one of the stable signs of falsification is the use of titanium white and organic catalysis products based on them. The results of gas chromatography and mass spectrometry and Raman spectroscopy are supplemented by X-ray phase and X-ray fluorescence analysis. The paper provides detailed reference data on the spectra of Raman light scattering, thermal desorption, and pyrolysis of paints of the studied canvases and shows the differences in the mass spectra of genuine paintings and falsifications.

The advantages of automated systems for magnetic inductive incoming quality control of raw materials of large metallurgical enterprises are demonstrated. Environmental risks under the existing visual control system were assessed.

Various methods of synthesis of CuInSe2 remain relevant because it is one of the most effective materials for solar energy. An effective method for the preparation of the CuInSe2 nanodispersed selenium precursor for microwave synthesis is considered. Colloidal selenium solutions were obtained using laser ablation in various liquid media: water, ethanol, triethylene glycol, polyethylene glycol–400 (PEG-400), and a 1% solution of PEG-1500 in PEG-400. The optical properties of the obtained colloidal selenium solutions were studied. Electron microscopy of selenium particles was conducted. Trends of ablation rate change and physicochemical properties of dispersed selenium particles in the variety of liquid media listed above are discussed. The possibility of synthesizing CuInSe2 using the obtained precursor was verified.

The use of spectral analysis methods to determine the age of writing inks is an important forensic task. However, the use of spectral data for this purpose has a number of limitations and difficulties. This paper considers the application of the Raman spectroscopy method to an urgent forensic task. The known mechanisms of dye de gradation are analyzed; Raman bands are identified that are related to the age of the sample. In a sample of 5 randomly selected writing inks, temporary markers were identified. Narrow sections of Raman spectra containing characteristic lines were used for analysis. It was shown that processing narrow sections of the Raman spectra using the PCA chemometric method allowed the separation of writing inks into groups (clusters) corresponding to different creation intervals.

In this work, we propose the promising approach that provides conditions for laser-induced ex situ synthesis of Raney-like copper-based nanostructured catalysts. Their catalytic activity and selectivity were investigated in Cu-catalyzed acetylene homo-coupling, Pd/Cu-catalyzed the Sonogashira cross-coupling and Cu-catalyzed azide-alkyne cycloaddition (CAAC). It was found that the growth of particles generated within the focus of the laser beam can last even if laser irradiation is off and can be controlled by adding phenanthroline to the reaction mixture as the stabilizing ligand or by increasing its temperature and concentration. Particle size of the synthesized copper-based catalysts significantly affects the reaction selectivity. Thus, it is possible to manage the course of the catalytic reaction towards formation of either homo-coupling or cross-coupling products by changing the size of the catalytically active copper-containing particles produced during laser-induced synthesis. (C) 2020 Elsevier Ltd. All rights reserved.

A brief review of modern methods for creating materials for enzymeless microbiosensors intended for express analysis of the content of components of biological fluids, including human blood, has been made. New directions of the synthesis of such materials have been described: laser ablation (PLD) and laser-induced deposition (LCLD). The comparison of laser methods for the synthesis of materials of non-enzymatic microbiosensors with the known methods for creating nanostructured materials has been carried out. Using bimetallic LCLD microtracks as an example, the mechanism of enhancing the electrochemical response of the sensor to the content of glucose and hydrogen peroxide in complex organic and biological mixtures has been shown. It is associated with the creation of nano- and microstructured materials with a highly developed surface, on which there are extended boundaries of the interphase contact zones. This creates numerous activated acid-base centers. They facilitate the transfer of charge from the oxidizing agent to the reducing agent in the solution in contact with the sensor surface. A comparison of the sensory properties of microcomposite bimetallic deposits synthesized by the laser method and their analogs synthesized by traditional methods has been carried out. The advantages of laser methods for the synthesis of microcomposite sensor-active materials are discussed: the miniature size of the sensors, the possibility of using inexpensive metals instead of precious ones, the environmental friendliness of the methods, and the absence of the need to pre-activate the surface

Nanocomposite membranes have been actively developed in the last decade. The involvement of nanostructures can improve the permeability, selectivity, and anti-fouling properties of a membrane for improved filtration processes. In this work, we propose a novel type of ion-selective Glass/Au composite membrane based on porous glass (PG), which combines the advantages of porous media and promising selective properties. The latter are achieved by depositing gold nanoparticles into the membrane pores by the laser-induced liquid phase chemical deposition technique. Inside the pores, gold nanoparticles with an average diameter 25 nm were formed, which was confirmed by optical and microscopic studies. To study the transport and selective properties of the PG/Au composite membrane, the potentiometric method was applied. The uniform potential model was used to determine the surface charge from the experimental data. It was found that the formation of gold nanoparticles inside membrane pores leads to an increase in the surface charge from −2.75 mC/m2 to −5.42 mC/m2. The methods proposed in this work allow the creation of a whole family of composite materials based on porous glasses. In this case, conceptually, the synthesis of these materials will differ only in the selection of initial precursors.

In this work we study the influence of l-(+)-КNaC4H4O6 × 4H2O (KNaT) and l-H2C4H4O6 (H2T) on the complexation processes occurring during in situ laser-induced catalytic destruction of the organic components of the aqueous solutions with formation of the unsaturated hydrocarbons. For that purpose, ATR-FTIR, Raman, IR, and NIR spectroscopy as well as quantum chemical calculations were implemented. It was observed that hydration of T2− anion via carboxylate groups is stronger than that via hydroxyl groups. We also established the changes in the spectral characteristics of the absorption bands corresponding to vibrations of T2−, HT−, and H2T, at solid state-liquid and acid-salt transitions, depending on concentration of the solution components and the [OH−]/[H2T] ratio. Finally, it was shown that ethylene is a main product of the catalytic destruction of the copper tartrate complexes.