G. Rizaev, Y. Grudtsyn, A. Ionin, O. Kosareva, A. Koribut, Y. Mityagin, D. Mokrousova, N. Panov, S. Savinov, L. Seleznev, D. Shipilo
Emission of THz radiation from a single-color ultraviolet (248 nm) and infrared (744 nm) filament in air is studied experimentally and compared at similar pulse durations, focusing conditions and excess of peak pulse power over the critical power for self-focusing. An angular distribution of the terahertz emission for both ultraviolet and infrared pump is conical with the closed cone angle. In contrast, the terahertz radiation energy and spectrum differ significantly. The energy of terahertz emission from ultraviolet filament is 1-2 orders of magnitude lower than the terahertz yield from the infrared filament. The terahertz spectrum of ultraviolet filament is shifted to the low-frequency range and narrower as compared to the spectrum of terahertz emission from infrared filament. We explain qualitatively the difference in terahertz yields and spectra by lower intensity and plasma density in the ultraviolet filament. Similar behavior of THz spectra is observed when changing the IR filament parameters.
{"title":"Comparison of terahertz radiation spectra emitted from single-color IR and UV filaments","authors":"G. Rizaev, Y. Grudtsyn, A. Ionin, O. Kosareva, A. Koribut, Y. Mityagin, D. Mokrousova, N. Panov, S. Savinov, L. Seleznev, D. Shipilo","doi":"10.1117/12.2543372","DOIUrl":"https://doi.org/10.1117/12.2543372","url":null,"abstract":"Emission of THz radiation from a single-color ultraviolet (248 nm) and infrared (744 nm) filament in air is studied experimentally and compared at similar pulse durations, focusing conditions and excess of peak pulse power over the critical power for self-focusing. An angular distribution of the terahertz emission for both ultraviolet and infrared pump is conical with the closed cone angle. In contrast, the terahertz radiation energy and spectrum differ significantly. The energy of terahertz emission from ultraviolet filament is 1-2 orders of magnitude lower than the terahertz yield from the infrared filament. The terahertz spectrum of ultraviolet filament is shifted to the low-frequency range and narrower as compared to the spectrum of terahertz emission from infrared filament. We explain qualitatively the difference in terahertz yields and spectra by lower intensity and plasma density in the ultraviolet filament. Similar behavior of THz spectra is observed when changing the IR filament parameters.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132632586","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}
Aleksandr V. Kraiski, Anton A. Kraiski, M. Kazaryan
Previously, was developed the method for calculating the light field inside a one-dimensional photonic crystal using perturbation theory by the value detuning from the band edge and calculating using this method the resonance properties of spectral transparency windows adjacent to band edge of a photonic crystal. The method allows to find the field when light propagates with frequencies lying near the band edge by using a set of eigenfunctions corresponding to the band edge for an infinite medium. The analytical expressions are obtained to describe this field and its characteristics, through these eigenfunctions. In the present work, the solution errors obtained by this method are investigated in comparison with direct computer-aided calculation of the field for a medium with a harmonic variation of the dielectric constant under various conditions for implementing this method. The problems of limiting the set of used spatial harmonics when calculating eigenfunctions (2 or more), limiting the number of eigenfunctions involved in constructing a solution (2 or more) are considered.
{"title":"Comparison of the characteristics of the light field in a one-dimensional photonic crystal with the harmonic dielectric constant obtained according to the theory of the perturbations and with the direct calculation","authors":"Aleksandr V. Kraiski, Anton A. Kraiski, M. Kazaryan","doi":"10.1117/12.2548865","DOIUrl":"https://doi.org/10.1117/12.2548865","url":null,"abstract":"Previously, was developed the method for calculating the light field inside a one-dimensional photonic crystal using perturbation theory by the value detuning from the band edge and calculating using this method the resonance properties of spectral transparency windows adjacent to band edge of a photonic crystal. The method allows to find the field when light propagates with frequencies lying near the band edge by using a set of eigenfunctions corresponding to the band edge for an infinite medium. The analytical expressions are obtained to describe this field and its characteristics, through these eigenfunctions. In the present work, the solution errors obtained by this method are investigated in comparison with direct computer-aided calculation of the field for a medium with a harmonic variation of the dielectric constant under various conditions for implementing this method. The problems of limiting the set of used spatial harmonics when calculating eigenfunctions (2 or more), limiting the number of eigenfunctions involved in constructing a solution (2 or more) are considered.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134081212","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}
An active waveguide-antenna in which the nonlinear crystal is the source of THz radiation is considered. The coherent terahertz radiation generated via optical rectification of 100 fs pulses of a Ti: sapphire laser in a system of a “nonlinear optical crystal partially filling the cross section of a metal rectangular waveguide” is investigated. It is shown that the fulfillment of the phase-matching condition and the optimization of the characteristics of radiation transmission through the integrated system “nonlinear crystal + waveguide” affect the efficiency of generation of THz radiation.
{"title":"Terahertz nonlinear waveguide-antenna driven by a femtosecond laser","authors":"A. Nikoghosyan, M. Kazaryan","doi":"10.1117/12.2548968","DOIUrl":"https://doi.org/10.1117/12.2548968","url":null,"abstract":"An active waveguide-antenna in which the nonlinear crystal is the source of THz radiation is considered. The coherent terahertz radiation generated via optical rectification of 100 fs pulses of a Ti: sapphire laser in a system of a “nonlinear optical crystal partially filling the cross section of a metal rectangular waveguide” is investigated. It is shown that the fulfillment of the phase-matching condition and the optimization of the characteristics of radiation transmission through the integrated system “nonlinear crystal + waveguide” affect the efficiency of generation of THz radiation.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115373388","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}
The paper presents measurement data on the radiation excited in synthetic diamonds, leucosapphire, and quartz KU1 at a wavelength of 200–800 nm by a pulsed electron beam with an energy of up to 400 keV. The crystals reveal wide bands whose intensity increases with decreasing wavelength in the range 220–400 nm. For leucosapphire and quartz, the radiation pulse at these wavelengths is close in duration to the electron beam current pulse, suggesting that it is Cherenkov radiation. For synthetic diamonds, both Cherenkov radiation and pulsed cathodoluminescence are detected in this spectral region. In particular, an intense band of free excitons with its maximum at 235 nm is found at high beam current densities and electron energies.
{"title":"Radiation in diamond, leucosapphire, and quartz under the excitation of electron beam with an energy of up to 400 keV","authors":"V. Tarasenko, V. Oleshko, E. Lipatov, M. Erofeev","doi":"10.1117/12.2550953","DOIUrl":"https://doi.org/10.1117/12.2550953","url":null,"abstract":"The paper presents measurement data on the radiation excited in synthetic diamonds, leucosapphire, and quartz KU1 at a wavelength of 200–800 nm by a pulsed electron beam with an energy of up to 400 keV. The crystals reveal wide bands whose intensity increases with decreasing wavelength in the range 220–400 nm. For leucosapphire and quartz, the radiation pulse at these wavelengths is close in duration to the electron beam current pulse, suggesting that it is Cherenkov radiation. For synthetic diamonds, both Cherenkov radiation and pulsed cathodoluminescence are detected in this spectral region. In particular, an intense band of free excitons with its maximum at 235 nm is found at high beam current densities and electron energies.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115611732","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}
L. Anikin, O. Lunina, S. Patsaeva, V. Rashidov, A. Zhiltsova
The work presents the results of spectroscopic study of the natural water with microorganisms from the splash baths in the Atlasov Island (the Alaid Volcano). The Alaid Volcano is the highest, northernmost and one of the most active volcanoes of the Kuril Islands, the unique object for interdisciplinary research. In 2015 within the supralittoral zone of the island the several splash pools filled with colored marine water were discovered for the first time. The paper presents the results of spectral measurements and microbiological studies performed on natural water samples taken in 2015-2017 from the supralittoral zone of the Alaid Volcano, the Kuril Islands, as well as the photosynthetic microorganisms cultivated from those samples in laboratory. The absorption spectra of the native samples and the cultures of photosynthetic bacteria cultivated from original water demonstrated pronounced maxima at 380, 590, 806, 854 nm wavelengths and the shoulders peaked at 510, 590 and 890 nm. The observed absorption maxima revealed the presence of bacteriochlorophyll а, the main photosynthetic pigment of purple sulfur bacteria, and additionally the cells of purple sulfur bacteria Thiocystis and Thiorhodococcus morphotypes were detected in water under microscope. Observation of water colored by photosynthetic microbes in different parts of the Atlasov Island within several summer seasons in 2015-2017 allowed us to conclude that the development of the purple phototrophic bacteria in the splash baths above the littoral zone is not an accidental event, but the stable phenomenon. On the other Kuril Islands similar splash baths have not been encountered yet.
{"title":"Optical characteristics of natural water samples collected in 2015-2017 in the supralittoral zone of the Alaid Volcano, the Kuril Islands","authors":"L. Anikin, O. Lunina, S. Patsaeva, V. Rashidov, A. Zhiltsova","doi":"10.1117/12.2540278","DOIUrl":"https://doi.org/10.1117/12.2540278","url":null,"abstract":"The work presents the results of spectroscopic study of the natural water with microorganisms from the splash baths in the Atlasov Island (the Alaid Volcano). The Alaid Volcano is the highest, northernmost and one of the most active volcanoes of the Kuril Islands, the unique object for interdisciplinary research. In 2015 within the supralittoral zone of the island the several splash pools filled with colored marine water were discovered for the first time. The paper presents the results of spectral measurements and microbiological studies performed on natural water samples taken in 2015-2017 from the supralittoral zone of the Alaid Volcano, the Kuril Islands, as well as the photosynthetic microorganisms cultivated from those samples in laboratory. The absorption spectra of the native samples and the cultures of photosynthetic bacteria cultivated from original water demonstrated pronounced maxima at 380, 590, 806, 854 nm wavelengths and the shoulders peaked at 510, 590 and 890 nm. The observed absorption maxima revealed the presence of bacteriochlorophyll а, the main photosynthetic pigment of purple sulfur bacteria, and additionally the cells of purple sulfur bacteria Thiocystis and Thiorhodococcus morphotypes were detected in water under microscope. Observation of water colored by photosynthetic microbes in different parts of the Atlasov Island within several summer seasons in 2015-2017 allowed us to conclude that the development of the purple phototrophic bacteria in the splash baths above the littoral zone is not an accidental event, but the stable phenomenon. On the other Kuril Islands similar splash baths have not been encountered yet.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"145 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123252200","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}
I. Shamanin, M. Kazaryan, S. Bedenko, V. Knyshev, V. Shamanin
The possibility of transformation of energy of fast and epithermal neutrons to energy of coherent photon radiation at the expense of a neutron pumping of the active medium formed by nucleus with long-living isomerous states is theoretically described. The channel of the nucleus formation in isomeric state as a daughter nucleus resulting from the nuclear reaction of neutron capture by a lighter nucleus is taken into consideration for the first time. The analysis of cross sections dependence of radiative neutron capture by the nuclei of gadolinium isotopes Gd155 and Gd156 is performed. As a result, it is stated that the speed of Gd156 nuclei formation exceeds the speed of their “burnup” in the neutron flux. It is provided by a unique combination of absorbing properties of two isotopes of gadolinium Gd155 and Gd156 in both thermal and resonance regions of neutron energy. The possibility of excess energy accumulation in the participating medium created by the nuclei of the pair of gadolinium isotopes Gd155 and Gd156 due to formation and storage of nuclei in isomeric state at radiative neutron capture by the nuclei of the stable isotope with a smaller mass is shown. It is concluded that when the active medium created by gadolinium nuclei is pumped by neutrons with the flux density of the order of 1013 cm-2·s-1, the condition of levels population inversion can be achieved in a few tens of seconds. The wave length of the radiation generated by the medium is 0.0006 nm.
{"title":"Dynamics of population of gadolinium-156 nuclei energy levels during neutron pumping of isotope-modified gadolinium oxide","authors":"I. Shamanin, M. Kazaryan, S. Bedenko, V. Knyshev, V. Shamanin","doi":"10.1117/12.2550338","DOIUrl":"https://doi.org/10.1117/12.2550338","url":null,"abstract":"The possibility of transformation of energy of fast and epithermal neutrons to energy of coherent photon radiation at the expense of a neutron pumping of the active medium formed by nucleus with long-living isomerous states is theoretically described. The channel of the nucleus formation in isomeric state as a daughter nucleus resulting from the nuclear reaction of neutron capture by a lighter nucleus is taken into consideration for the first time. The analysis of cross sections dependence of radiative neutron capture by the nuclei of gadolinium isotopes Gd155 and Gd156 is performed. As a result, it is stated that the speed of Gd156 nuclei formation exceeds the speed of their “burnup” in the neutron flux. It is provided by a unique combination of absorbing properties of two isotopes of gadolinium Gd155 and Gd156 in both thermal and resonance regions of neutron energy. The possibility of excess energy accumulation in the participating medium created by the nuclei of the pair of gadolinium isotopes Gd155 and Gd156 due to formation and storage of nuclei in isomeric state at radiative neutron capture by the nuclei of the stable isotope with a smaller mass is shown. It is concluded that when the active medium created by gadolinium nuclei is pumped by neutrons with the flux density of the order of 1013 cm-2·s-1, the condition of levels population inversion can be achieved in a few tens of seconds. The wave length of the radiation generated by the medium is 0.0006 nm.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124496329","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}
S. Arakelyan, A. A. Asratyan, V. L. Evstigneev, M. Kazaryan, M. Gerke, A. Galkin, S. Zhirnova, A. Osipov, G. Evstyunin, E. Shamanskaya, R. Zakharyan, A. S. Averyushkin, O. Andrienko, P. I. Ivashkin
Presents the operation of a system for monitoring the process of laser processing of the surface of materials in real time, with a resolution of the order of several tens of nanoseconds, with a micron-scale spatial resolution designed to visualize laser-induced dynamic processes directly during laser processing of the surface of an object. The basic physical principles of its operation and the problems existing at the same time, as well as the prospects for overcoming them in various conditions of specific processes of laser thermal strengthening, including using computer simulation to search for optimal optical circuits and modes. The dynamic characteristics of the laser monitoring system are given.
{"title":"Dynamic characteristics of a laser system for controlling an object's impact","authors":"S. Arakelyan, A. A. Asratyan, V. L. Evstigneev, M. Kazaryan, M. Gerke, A. Galkin, S. Zhirnova, A. Osipov, G. Evstyunin, E. Shamanskaya, R. Zakharyan, A. S. Averyushkin, O. Andrienko, P. I. Ivashkin","doi":"10.1117/12.2550625","DOIUrl":"https://doi.org/10.1117/12.2550625","url":null,"abstract":"Presents the operation of a system for monitoring the process of laser processing of the surface of materials in real time, with a resolution of the order of several tens of nanoseconds, with a micron-scale spatial resolution designed to visualize laser-induced dynamic processes directly during laser processing of the surface of an object. The basic physical principles of its operation and the problems existing at the same time, as well as the prospects for overcoming them in various conditions of specific processes of laser thermal strengthening, including using computer simulation to search for optimal optical circuits and modes. The dynamic characteristics of the laser monitoring system are given.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123552517","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}
A. Knyazkova, Polina V. Shulmina, Y. Kistenev, А. А. Markelov, M. B. Miroshnichenko, A. Borisov
Low-level laser exposure is a non-invasive and less painful method, which is used as an alternative method to classical acupuncture with metal needles and could be applied in clinical medical practice. The study of the laser acupuncture effect on the electroencephalogram (EEG) characteristics was carried out. The electrodes were located on the surface of the subject's head according to the standard scheme 10-20. Experimental EEG data were obtained by standard digital 16-channel electroencephalograph with EEG18 V5.0.3 software. The EEG frequencies in each of the measurements have been analyzed. This work shows that low-level laser stimulation able to change the power of rhythms in the head areas, which corresponds to the stimulation of different brain regions.
{"title":"Influence of laser acupuncture on EEG characteristics","authors":"A. Knyazkova, Polina V. Shulmina, Y. Kistenev, А. А. Markelov, M. B. Miroshnichenko, A. Borisov","doi":"10.1117/12.2550757","DOIUrl":"https://doi.org/10.1117/12.2550757","url":null,"abstract":"Low-level laser exposure is a non-invasive and less painful method, which is used as an alternative method to classical acupuncture with metal needles and could be applied in clinical medical practice. The study of the laser acupuncture effect on the electroencephalogram (EEG) characteristics was carried out. The electrodes were located on the surface of the subject's head according to the standard scheme 10-20. Experimental EEG data were obtained by standard digital 16-channel electroencephalograph with EEG18 V5.0.3 software. The EEG frequencies in each of the measurements have been analyzed. This work shows that low-level laser stimulation able to change the power of rhythms in the head areas, which corresponds to the stimulation of different brain regions.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123989035","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}
A. Pashayev, B. Tagiyev, O. B. Tagiyev, K. Allahverdiyev, I. Huseynov, I. Sadikhov
A wide range of rare earth doped crystals used as a lasing media includes: Y3Al5O12 (YAG); Al2O3 (sapphire); chalcogenides of ZnS, ZnSe; sesquioxides of Y2O3, Sc2O3 and others. Ternary thiogallate compounds with common formula AIIB23C4 6 (where A is: Ca, Sr, Ba; B is: Ga, Al; C is- S, Se, Te) consider as a perspective class of chalcogenide semiconductors revealing bright luminescence and laser oscillation properties when doped with rare-earth elements (Eu2+, Nd3+ , Ce3+ etc). In the present research, optical properties and observed laser oscillation of transparent ternary chalcogenide crystals of CaGa2S4 and CaGa2Se4 grown by the chemical vapor transport reaction and doped with Eu2+ (1.0-5.0 a t%) are described. The first observation of laser oscillation from a single crystal CaGa2S4 : Eu2+ (1.0-5.0 at%) have been reported earlier, and for CaGa2Se4 : Eu2+ it is reported for the first time in the present article. The life time of the excited state 4f65d of Eu2+ ions in both crystals determined from the luminescence decay kinetics was ~3.8 μsec. It is shown that photoluminescence maximum in both crystals CaGa2S4 : Eu2+ and CaGa2Se4 : Eu2+ is due to the intra shell transition 4f65d – 4f7(8S7/2) ions.
{"title":"Growth and investigation of optical properties and laser oscillations from ternary thiogallate crystals with laser active dopants","authors":"A. Pashayev, B. Tagiyev, O. B. Tagiyev, K. Allahverdiyev, I. Huseynov, I. Sadikhov","doi":"10.1117/12.2542947","DOIUrl":"https://doi.org/10.1117/12.2542947","url":null,"abstract":"A wide range of rare earth doped crystals used as a lasing media includes: Y3Al5O12 (YAG); Al2O3 (sapphire); chalcogenides of ZnS, ZnSe; sesquioxides of Y2O3, Sc2O3 and others. Ternary thiogallate compounds with common formula AIIB23C4 6 (where A is: Ca, Sr, Ba; B is: Ga, Al; C is- S, Se, Te) consider as a perspective class of chalcogenide semiconductors revealing bright luminescence and laser oscillation properties when doped with rare-earth elements (Eu2+, Nd3+ , Ce3+ etc). In the present research, optical properties and observed laser oscillation of transparent ternary chalcogenide crystals of CaGa2S4 and CaGa2Se4 grown by the chemical vapor transport reaction and doped with Eu2+ (1.0-5.0 a t%) are described. The first observation of laser oscillation from a single crystal CaGa2S4 : Eu2+ (1.0-5.0 at%) have been reported earlier, and for CaGa2Se4 : Eu2+ it is reported for the first time in the present article. The life time of the excited state 4f65d of Eu2+ ions in both crystals determined from the luminescence decay kinetics was ~3.8 μsec. It is shown that photoluminescence maximum in both crystals CaGa2S4 : Eu2+ and CaGa2Se4 : Eu2+ is due to the intra shell transition 4f65d – 4f7(8S7/2) ions.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125569643","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}
A. Nizamutdinov, T. A. Telegina, A. A. Buglak, E. Lukinova, E. Madirov, Yuliya L. Vechtomova, M. S. Kritsky, V. Semashko
Melanogenesis disorder leads to several pathologies, including vitiligo. Tetrahydrobiopterin (H4Bip) as the phenylalanine 4-hydroxylase coenzyme catalyzes the oxidation of phenylalanine to tyrosine (a melanin precursor). H4Bip is easily oxidized by oxygen in vivo and in vitro. Vitiligo is accompanied by three-fivefold increased de-novo synthesis of H4Bip, its excess and its further oxidation are essential factors in the pathogenesis of vitiligo. We have demonstrated that pterin products of H4Bip autoxidation (dihydropterin (H2Ptr), dihydroxanthopterin and pterin) predominate over biopterin products (dihydrobiopterin (H2Bip) and biopterin). It was shown that ultraviolet (UV) irradiation accelerates the autoxidation while the products of oxidative degradation of H4Bip act as photosensitizers. Photosensitized oxidation of H4Bip can contribute to the pathogenesis of vitiligo. The main distinguishing feature of UV photooxidation of H4Bip from autoxidation was the formation of dihydropterin (Н2Ptr)2 and dihydrobiopterin (Н2Bip)2 dimers. Here we reported on the dependences of the photodimerization reaction on the wavelength and intensity of radiation using xenon lamps and UV tunable lasers as sources of UV radiation. It was shown that UV irradiation with a laser is more efficient than that with xenon lamp. It was established that the greatest number of dimers were formed by irradiating the H4Bip solution by radiation with a wavelength in the range 308-312 nm. The data obtained are discussed in the context of UVB narrowband vitiligo phototherapy.
{"title":"The role of photochemical transformations of tetrahydrobiopterin in the pathogenesis and phototherapy of vitiligo","authors":"A. Nizamutdinov, T. A. Telegina, A. A. Buglak, E. Lukinova, E. Madirov, Yuliya L. Vechtomova, M. S. Kritsky, V. Semashko","doi":"10.1117/12.2555041","DOIUrl":"https://doi.org/10.1117/12.2555041","url":null,"abstract":"Melanogenesis disorder leads to several pathologies, including vitiligo. Tetrahydrobiopterin (H4Bip) as the phenylalanine 4-hydroxylase coenzyme catalyzes the oxidation of phenylalanine to tyrosine (a melanin precursor). H4Bip is easily oxidized by oxygen in vivo and in vitro. Vitiligo is accompanied by three-fivefold increased de-novo synthesis of H4Bip, its excess and its further oxidation are essential factors in the pathogenesis of vitiligo. We have demonstrated that pterin products of H4Bip autoxidation (dihydropterin (H2Ptr), dihydroxanthopterin and pterin) predominate over biopterin products (dihydrobiopterin (H2Bip) and biopterin). It was shown that ultraviolet (UV) irradiation accelerates the autoxidation while the products of oxidative degradation of H4Bip act as photosensitizers. Photosensitized oxidation of H4Bip can contribute to the pathogenesis of vitiligo. The main distinguishing feature of UV photooxidation of H4Bip from autoxidation was the formation of dihydropterin (Н2Ptr)2 and dihydrobiopterin (Н2Bip)2 dimers. Here we reported on the dependences of the photodimerization reaction on the wavelength and intensity of radiation using xenon lamps and UV tunable lasers as sources of UV radiation. It was shown that UV irradiation with a laser is more efficient than that with xenon lamp. It was established that the greatest number of dimers were formed by irradiating the H4Bip solution by radiation with a wavelength in the range 308-312 nm. The data obtained are discussed in the context of UVB narrowband vitiligo phototherapy.","PeriodicalId":205170,"journal":{"name":"Atomic and Molecular Pulsed Lasers","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126390927","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}
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