Pub Date : 2022-06-22DOI: 10.33581/2520-2243-2022-2-50-59
A. Spiridonov, V. Baranova, V. Saetchnikov, Dmitrii Ushakov
The roadmap for constructing a regional nanosatellite constellation using the piggyback launch according to Chinese provider information has developed. For nanosatellite constellation formation to a specific purpose, it is necessary to analyse existing constellation operated similar tasks. Therefore, the software module for the Spire Global constellation orbital construction analysis was developed. The construction of Spire Global nanosatellites constellation based on orbital parameters database in the two-line element set format, satellite constellation databases and the developer site was analysed. A launch from the International Space Station and a piggyback launch were used for constellation formation. Nanosatellite deployment schemes, orbital parameters and flight parameters are investigated launches from the Taiyuan and Jiuquan Satellite Launch Centers with orbit inclination about 90°, that best correspond to the passes over Minsk (ϕ = 53°54′27″ N, λ = 27°33′52″ E) are analysed. The method of nanosatellite orbit preflight prediction at a passing launch has been developed. It involves a finding the nanosatellite state vector in the first flight day and at the time of constellation mission operate start. The launch time, satellite launch center coordinates, launch vehicle type, orbit inclination and altitude (period) are used in the method. In addition, the launch history and the satellite motion dynamics analysis on similar orbits is carried out. It was found that five launches are enough to organise a regional nanosatellite constellation with average radio visibility interruption time of at least 36 min with a maximum value of 85 min.
{"title":"The regional nanosatellite constellation modelling formation by a piggyback launch from different spaceports","authors":"A. Spiridonov, V. Baranova, V. Saetchnikov, Dmitrii Ushakov","doi":"10.33581/2520-2243-2022-2-50-59","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-50-59","url":null,"abstract":"The roadmap for constructing a regional nanosatellite constellation using the piggyback launch according to Chinese provider information has developed. For nanosatellite constellation formation to a specific purpose, it is necessary to analyse existing constellation operated similar tasks. Therefore, the software module for the Spire Global constellation orbital construction analysis was developed. The construction of Spire Global nanosatellites constellation based on orbital parameters database in the two-line element set format, satellite constellation databases and the developer site was analysed. A launch from the International Space Station and a piggyback launch were used for constellation formation. Nanosatellite deployment schemes, orbital parameters and flight parameters are investigated launches from the Taiyuan and Jiuquan Satellite Launch Centers with orbit inclination about 90°, that best correspond to the passes over Minsk (ϕ = 53°54′27″ N, λ = 27°33′52″ E) are analysed. The method of nanosatellite orbit preflight prediction at a passing launch has been developed. It involves a finding the nanosatellite state vector in the first flight day and at the time of constellation mission operate start. The launch time, satellite launch center coordinates, launch vehicle type, orbit inclination and altitude (period) are used in the method. In addition, the launch history and the satellite motion dynamics analysis on similar orbits is carried out. It was found that five launches are enough to organise a regional nanosatellite constellation with average radio visibility interruption time of at least 36 min with a maximum value of 85 min.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88992350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-20DOI: 10.33581/2520-2243-2022-2-4-11
D. Tarasau, M. Samtsov, Nikita N. Krasnoperov
The interaction of indotricarbocyanine dyes with human blood serum proteins was studied. The spectral and fluorescent properties of dyes in butanol, Dulbecco’s sodium and potassium phosphate buffer (0.14 mol/L) with pH 7.4, and human blood serum solutions were determined. It was shown that the spectral properties of dyes in butanol differ significantly from the spectral properties in solutions of Dulbecco’s sodium and potassium phosphate buffer and human blood serum, and that butanol effectively extracts the molecules of the studied dyes that do not form covalently bound complexes with blood serum components. By analysing the extraction products, the proportion of covalent complexes of dyes with protein molecules was determined. It has been established that indotricarbocyanine dyes with a chlorine-substituted orthophenylene bridge in the conjugation chain are partially passes into butanol, the degree of extraction depends on the ratio of dye and protein concentrations. Thus, at a concentration of 10 mmol/L in 5 % human serum, the degree of extraction of these dyes is ~50 – 60 % respectively, the proportion of dye molecules in strong covalently bound complexes with blood serum components is ~ 40 –50 %. On the contrary, the dye with a free polymethine chain is extracted almost completely (91.4 % extraction rate). The indotricarbocyanine dyes are promising for use as a photosensitisers for photodynamic therapy.
{"title":"Regularities of complexation of indotricarbocyanine dyes with human blood serum proteins","authors":"D. Tarasau, M. Samtsov, Nikita N. Krasnoperov","doi":"10.33581/2520-2243-2022-2-4-11","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-4-11","url":null,"abstract":"The interaction of indotricarbocyanine dyes with human blood serum proteins was studied. The spectral and fluorescent properties of dyes in butanol, Dulbecco’s sodium and potassium phosphate buffer (0.14 mol/L) with pH 7.4, and human blood serum solutions were determined. It was shown that the spectral properties of dyes in butanol differ significantly from the spectral properties in solutions of Dulbecco’s sodium and potassium phosphate buffer and human blood serum, and that butanol effectively extracts the molecules of the studied dyes that do not form covalently bound complexes with blood serum components. By analysing the extraction products, the proportion of covalent complexes of dyes with protein molecules was determined. It has been established that indotricarbocyanine dyes with a chlorine-substituted orthophenylene bridge in the conjugation chain are partially passes into butanol, the degree of extraction depends on the ratio of dye and protein concentrations. Thus, at a concentration of 10 mmol/L in 5 % human serum, the degree of extraction of these dyes is ~50 – 60 % respectively, the proportion of dye molecules in strong covalently bound complexes with blood serum components is ~ 40 –50 %. On the contrary, the dye with a free polymethine chain is extracted almost completely (91.4 % extraction rate). The indotricarbocyanine dyes are promising for use as a photosensitisers for photodynamic therapy.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"123 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84944125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-15DOI: 10.33581/2520-2243-2022-2-60-69
A. Lamaka
The work is devoted to the study and modification of existing methods for merging a number of images obtained using a multispectral camera installed on an unmanned aerial vehicle into a single panoramic image for the purpose of its further thematic processing. A generalised method based on the existing detectors and descriptors of special areas of images was proposed for the automated solution of this issue, as well as the developed method for filtering matches of special areas. An analysis was carried out to select the best detectors and descriptors of special areas for the tasks of merging images of forest areas. It has been determined that the combination of ORB and FREAK methods show better results in detecting and describing specific points to perform the above tasks, than BRISK, SURF and ORB methods. Particular attention is paid to the importance of determining and correcting camera distortion used in data acquisition, the method used and the results of distortion correction are described. The effect of camera distortion to the displacement between singular points standard deviation in the case of data alignment is estimated. It is shown that the proposed automatic obtaining panoramic multispectral images method makes it possible to connect images with an average accuracy of up to 5 pixels when solving connection of multispectral images set issues.
{"title":"Considering camera distortion panoramic images forming method for unmanned aerial vehicle multispectral data","authors":"A. Lamaka","doi":"10.33581/2520-2243-2022-2-60-69","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-60-69","url":null,"abstract":"The work is devoted to the study and modification of existing methods for merging a number of images obtained using a multispectral camera installed on an unmanned aerial vehicle into a single panoramic image for the purpose of its further thematic processing. A generalised method based on the existing detectors and descriptors of special areas of images was proposed for the automated solution of this issue, as well as the developed method for filtering matches of special areas. An analysis was carried out to select the best detectors and descriptors of special areas for the tasks of merging images of forest areas. It has been determined that the combination of ORB and FREAK methods show better results in detecting and describing specific points to perform the above tasks, than BRISK, SURF and ORB methods. Particular attention is paid to the importance of determining and correcting camera distortion used in data acquisition, the method used and the results of distortion correction are described. The effect of camera distortion to the displacement between singular points standard deviation in the case of data alignment is estimated. It is shown that the proposed automatic obtaining panoramic multispectral images method makes it possible to connect images with an average accuracy of up to 5 pixels when solving connection of multispectral images set issues.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85792642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-15DOI: 10.33581/2520-2243-2022-2-70-78
O. Y. Nalivaiko, Arcady S. Turtsevich, V. Plebanovich, P. Gaiduk
The investigation of initial stage of Si1 – xGex alloy deposition and clarification of Ge nanocrystal formation mechanism has been carried out. It was found that at the initial stages of growing layers of Si1 – xGex alloys, the density of island nuclei Si1 – xGex increases by a factor of 2.5–3.4 compared to the density of polycrystalline silicon islands (from 1.07 ⋅ 1011 to 1.90 ⋅ 1011 cm–2 and from 3.1 ⋅ 1010 to 4.3 ⋅ 1010 cm–2 respectively). A decrease in the thickness of the layer corresponding to the end of the induction period and the formation of a continuous Si1 – xGex layer to 8–10 nm (for polycrystalline silicon, the thickness of a similar layer is approximately 22 nm) has been established. It is shown that the Ge nanocrystal formation is occurred by segregationist pushback of Ge atoms by the SiO2 /Si1 – xGex oxidation front and oxidation through grain boundaries during oxidation of Si1 – xGex thin layers, produced by chemical vapor deposition. The MOS structure with array of Ge nanocrystal, which has the hysteresis capacitance characteristics of 1.7–1.8 V and leakage current density from 1.5 ⋅ 10–16 to 2.2 ⋅ 10–16 A/µm2 was obtained.
{"title":"Segregation-induced formation of Ge nanocrystals in silicon oxide","authors":"O. Y. Nalivaiko, Arcady S. Turtsevich, V. Plebanovich, P. Gaiduk","doi":"10.33581/2520-2243-2022-2-70-78","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-70-78","url":null,"abstract":"The investigation of initial stage of Si1 – xGex alloy deposition and clarification of Ge nanocrystal formation mechanism has been carried out. It was found that at the initial stages of growing layers of Si1 – xGex alloys, the density of island nuclei Si1 – xGex increases by a factor of 2.5–3.4 compared to the density of polycrystalline silicon islands (from 1.07 ⋅ 1011 to 1.90 ⋅ 1011 cm–2 and from 3.1 ⋅ 1010 to 4.3 ⋅ 1010 cm–2 respectively). A decrease in the thickness of the layer corresponding to the end of the induction period and the formation of a continuous Si1 – xGex layer to 8–10 nm (for polycrystalline silicon, the thickness of a similar layer is approximately 22 nm) has been established. It is shown that the Ge nanocrystal formation is occurred by segregationist pushback of Ge atoms by the SiO2 /Si1 – xGex oxidation front and oxidation through grain boundaries during oxidation of Si1 – xGex thin layers, produced by chemical vapor deposition. The MOS structure with array of Ge nanocrystal, which has the hysteresis capacitance characteristics of 1.7–1.8 V and leakage current density from 1.5 ⋅ 10–16 to 2.2 ⋅ 10–16 A/µm2 was obtained.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83850541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.33581/2520-2243-2022-2-87-98
S. Sytova
The article provides an overview of the basic concepts in the field of knowledge management, taking into account the recommendations of the United Nations in this area, as well as the nuclear knowledge management from the perspective of the International Atomic Energy Agency. The assessment of the state of nuclear knowledge management in the world, Eurasian Economic Union countries and Republic of Belarus has been carried out. The information and analytical activities and the specifics of the work of the national regulator in the field of nuclear and radiation safety – Department of Nuclear and Radiation Safety of the Ministry for Emergency Situations of the Republic of Belarus (Gosatomnadzor) – in the field of nuclear knowledge management were analysed, as well as the best practices in this area in the Republic of Belarus. A description of modern information technologies for nuclear knowledge management system is given, including the further development of the capabilities and tools of software products – Intellectual information system of an employee of Gosatomnadzor to ensure control (supervision) in the field of nuclear and radiation safety and electronic portal of nuclear knowledge of the Republic of Belarus BelNET (https://belnet.bsu.by/ ). The basic principles for work and further development of nuclear knowledge management system in the Republic of Belarus are presented.
{"title":"Nuclear knowledge management system in the Republic of Belarus","authors":"S. Sytova","doi":"10.33581/2520-2243-2022-2-87-98","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-87-98","url":null,"abstract":"The article provides an overview of the basic concepts in the field of knowledge management, taking into account the recommendations of the United Nations in this area, as well as the nuclear knowledge management from the perspective of the International Atomic Energy Agency. The assessment of the state of nuclear knowledge management in the world, Eurasian Economic Union countries and Republic of Belarus has been carried out. The information and analytical activities and the specifics of the work of the national regulator in the field of nuclear and radiation safety – Department of Nuclear and Radiation Safety of the Ministry for Emergency Situations of the Republic of Belarus (Gosatomnadzor) – in the field of nuclear knowledge management were analysed, as well as the best practices in this area in the Republic of Belarus. A description of modern information technologies for nuclear knowledge management system is given, including the further development of the capabilities and tools of software products – Intellectual information system of an employee of Gosatomnadzor to ensure control (supervision) in the field of nuclear and radiation safety and electronic portal of nuclear knowledge of the Republic of Belarus BelNET (https://belnet.bsu.by/ ). The basic principles for work and further development of nuclear knowledge management system in the Republic of Belarus are presented.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83575825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-08DOI: 10.33581/2520-2243-2022-2-79-86
M. V. Lobanok, S. L. Prakopyeu, M. Makhavikou, O. Korolik, P. Gaiduk
The results of a study of the structure and phase composition of epitaxial layers of silicon carbide (SiC) formed on silicon substrate with orientation (100) under rapid vacuum thermal processing are presented. Planar-view transmission electron microscopy investigation revealed the formation of epitaxial layers of cubic polytype SiC (3C-SiC) on silicon in the process of carbidisation at 1100 °C during 30 s, using a gas mixture of propane (10 %) and argon (90 %) as a carbon source. The formation of a monocrystalline 3C-SiC with polycrystalline inclusions and twins on all possible planes {111} was found. A rather narrow band of 793 cm–1 transverse optical phonon mode SiC on Raman spectra confirms the formation of a cubic polytype SiC. It is noted that the presence of a 180 cm–1 spectral line and a 793 cm–1 half-width band on Raman spectra indicate the presence of deformation defects in SiC.
{"title":"Formation of epitaxial 3C-SiC layers on Si by rapid vacuum thermal processing","authors":"M. V. Lobanok, S. L. Prakopyeu, M. Makhavikou, O. Korolik, P. Gaiduk","doi":"10.33581/2520-2243-2022-2-79-86","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-79-86","url":null,"abstract":"The results of a study of the structure and phase composition of epitaxial layers of silicon carbide (SiC) formed on silicon substrate with orientation (100) under rapid vacuum thermal processing are presented. Planar-view transmission electron microscopy investigation revealed the formation of epitaxial layers of cubic polytype SiC (3C-SiC) on silicon in the process of carbidisation at 1100 °C during 30 s, using a gas mixture of propane (10 %) and argon (90 %) as a carbon source. The formation of a monocrystalline 3C-SiC with polycrystalline inclusions and twins on all possible planes {111} was found. A rather narrow band of 793 cm–1 transverse optical phonon mode SiC on Raman spectra confirms the formation of a cubic polytype SiC. It is noted that the presence of a 180 cm–1 spectral line and a 793 cm–1 half-width band on Raman spectra indicate the presence of deformation defects in SiC.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83638015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-06DOI: 10.33581/2520-2243-2022-2-39-49
G. Gusakov, M. V. Puzyrev, I. Gorudko, E. V. Shamova, Radislav N. Dorozhkin
The process of silver ablation in water by high-power laser pulses (λ = 1064 nm, τ = 20 ns) in the power density range from 2.6 ⋅ 108 to 5.5 ⋅ 108 W/cm2 has been investigated. The dependences of the ablation efficiency and the size distribution of silver nanoparticles on the power density of laser radiation and on the duration of synthesis have been determined. It was found that the resulting nanoparticles have a multimodal size distribution, in which three fractions with average sizes of 5; 50 and more than 100 nm can be distinguished. Particles with a diameter of more than 100 nm are formed as a result of the removal of the liquid-droplet phase directly from the target surface due to the hydrodynamic mechanism, particles 5 and 50 nm in size are formed due to condensation at different stages of cooling of the vapor-plasma formation. The proportion of these fractions in the silver sol is determined by the effective density of the laser power on the target surface. It is shown that pulsed laser irradiation of a sol of silver nanoparticles after the completion of the synthesis process makes it possible to significantly narrow the particle size distribution and increase the stability of the resulting suspension. It was found that the synthesised silver nanoparticles deposited on a silicon substrate can effectively enhance the Raman signal of human serum albumin.
{"title":"Synthesis and optical characteristics of silver nanoparticles produced by laser ablation of metal in liquid","authors":"G. Gusakov, M. V. Puzyrev, I. Gorudko, E. V. Shamova, Radislav N. Dorozhkin","doi":"10.33581/2520-2243-2022-2-39-49","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-39-49","url":null,"abstract":"The process of silver ablation in water by high-power laser pulses (λ = 1064 nm, τ = 20 ns) in the power density range from 2.6 ⋅ 108 to 5.5 ⋅ 108 W/cm2 has been investigated. The dependences of the ablation efficiency and the size distribution of silver nanoparticles on the power density of laser radiation and on the duration of synthesis have been determined. It was found that the resulting nanoparticles have a multimodal size distribution, in which three fractions with average sizes of 5; 50 and more than 100 nm can be distinguished. Particles with a diameter of more than 100 nm are formed as a result of the removal of the liquid-droplet phase directly from the target surface due to the hydrodynamic mechanism, particles 5 and 50 nm in size are formed due to condensation at different stages of cooling of the vapor-plasma formation. The proportion of these fractions in the silver sol is determined by the effective density of the laser power on the target surface. It is shown that pulsed laser irradiation of a sol of silver nanoparticles after the completion of the synthesis process makes it possible to significantly narrow the particle size distribution and increase the stability of the resulting suspension. It was found that the synthesised silver nanoparticles deposited on a silicon substrate can effectively enhance the Raman signal of human serum albumin.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74382487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-06DOI: 10.33581/2520-2243-2022-2-26-38
V. Tarkovsky
The generation efficiency of a number of ethanol dye solutions is studied as a function of the coherent microsecond pump wavelength. It is shown that the maximum lasing efficiency is achieved by pumping not to the maximum of the main band of the absorption spectrum of dyes. In the spectral ranges determined for each dye, a decrease in the generation efficiency is observed. The reasons for this phenomenon – triplet-triplet and singlet-singlet absorption – are analised. The main role in the case under consideration is played by the absorption of pump radiation in the system of excited singlet levels with the formation of long- and short-lived photoproducts that absorb in the amplification region but do not participate in generation. A study of the luminescence kinetics of the DCM dye showed that another reason for the appearance of induced losses is the non-linear scattering of radiation in a dye solution, which occurs because of non-stationary self-diffraction of pump radiation on phase noise gratings formed as a result of heat release when light is absorbed in the channel of excited singlet levels in a bleaching dye solution. Experiments on probing induced losses, as well as picosecond spectroscopy, confirmed the appearance of thermooptical distortions of the active medium in certain spectral intervals of microsecond coherent pumping.
{"title":"Influence on the generating losses on the spectral efficiency of ethanol solutions of dyes of various classes","authors":"V. Tarkovsky","doi":"10.33581/2520-2243-2022-2-26-38","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-26-38","url":null,"abstract":"The generation efficiency of a number of ethanol dye solutions is studied as a function of the coherent microsecond pump wavelength. It is shown that the maximum lasing efficiency is achieved by pumping not to the maximum of the main band of the absorption spectrum of dyes. In the spectral ranges determined for each dye, a decrease in the generation efficiency is observed. The reasons for this phenomenon – triplet-triplet and singlet-singlet absorption – are analised. The main role in the case under consideration is played by the absorption of pump radiation in the system of excited singlet levels with the formation of long- and short-lived photoproducts that absorb in the amplification region but do not participate in generation. A study of the luminescence kinetics of the DCM dye showed that another reason for the appearance of induced losses is the non-linear scattering of radiation in a dye solution, which occurs because of non-stationary self-diffraction of pump radiation on phase noise gratings formed as a result of heat release when light is absorbed in the channel of excited singlet levels in a bleaching dye solution. Experiments on probing induced losses, as well as picosecond spectroscopy, confirmed the appearance of thermooptical distortions of the active medium in certain spectral intervals of microsecond coherent pumping.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76416813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-06DOI: 10.33581/2520-2243-2022-2-19-25
Slavamir S. Anufrik, V. Tarkovsky, Sergey N. Anuchin
The spectral and generation parameters of coumarins, benzopyrylium derivatives, in ethanol and acetonitrile under coherent excitation were studied. It was found that the absorption spectra of the investigated compounds contain several maxima and the structuredness of the spectra is associated with their bichromophoric structure. It is shown that these organic dyes are bichromophoric compounds. It is noted that the nature of the substituents in positions 6 and 7 of the coumarin base and positions 6′ and 7′ of the benzopyrylium core determines their spectral-luminescent and lasing properties. It is demonstrated that the presence of substituents in certain positions of the coumarin base and the benzopyrylium core changes the conformation of the molecule and, accordingly, the dipole moments and oscillator strengths of the transition. The generation ability of coumarins of this class manifests itself only in the presence of the strongest donor substituents (for example, Et2N and OH) in position 7, and sufficiently strong acceptors in positions 6′ and 7′. Lasing was obtained in the spectral region of 730 –740 nm on dyes – benzopyrylium derivatives.
{"title":"Spectral and generation properties of new coumarins – benzopyrylium derivatives","authors":"Slavamir S. Anufrik, V. Tarkovsky, Sergey N. Anuchin","doi":"10.33581/2520-2243-2022-2-19-25","DOIUrl":"https://doi.org/10.33581/2520-2243-2022-2-19-25","url":null,"abstract":"The spectral and generation parameters of coumarins, benzopyrylium derivatives, in ethanol and acetonitrile under coherent excitation were studied. It was found that the absorption spectra of the investigated compounds contain several maxima and the structuredness of the spectra is associated with their bichromophoric structure. It is shown that these organic dyes are bichromophoric compounds. It is noted that the nature of the substituents in positions 6 and 7 of the coumarin base and positions 6′ and 7′ of the benzopyrylium core determines their spectral-luminescent and lasing properties. It is demonstrated that the presence of substituents in certain positions of the coumarin base and the benzopyrylium core changes the conformation of the molecule and, accordingly, the dipole moments and oscillator strengths of the transition. The generation ability of coumarins of this class manifests itself only in the presence of the strongest donor substituents (for example, Et2N and OH) in position 7, and sufficiently strong acceptors in positions 6′ and 7′. Lasing was obtained in the spectral region of 730 –740 nm on dyes – benzopyrylium derivatives.","PeriodicalId":17264,"journal":{"name":"Journal of the Belarusian State University. Physics","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86238066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-03DOI: 10.33581/2520-2243-2022-2-12-18
M. Khodasevich, D. Borisevich, V. Aseev, N. Kuzmenko, Irina M. Sevastianova
The use of neodymium-doped nanocrystalline powders of yttrium-gadolinium oxide and yttrium gadolinium garnet to increase the sensitivity of local fluorescent optical temperature sensors is considered. Based on the temperature dependences of the neodymium fluorescence spectra in this powders, univariate (using fluorescence intensity ratio from thermally coupled energy levels of the activator) and multivariate (using the partial least squares method) calibration models are developed. When using the spectral range 860 – 950 nm falling into the first biological transparency window (700 – 980 nm), both calibration models have a standard deviation of about 10 % and are comparable in accuracy. The spectral variables selection by searching combination moving window in the multivariate model made it possible to reduce the root mean square error for yttrium-gadolinium oxide by more than 12 times (from 9.8 to 0.8 °C), and for yttrium-gadolinium garnet by more than 2 times(from 8.7 to 4.0 °С). The result obtained indicatesthe proposed neodymium-doped nanocrystalline powders and multivariate methods of calibration can be used to localise areas with febrile temperatures for biological and medical purposes.
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