A. Kazaryan, M. Kazaryan, S. V. Kruzhalov, Y. Mokrushin, V. A. Parfionov
Comparative study has been performed of the influence of pumping by two separated wavelengths λ equals 520.6 and λ equals 578.2 nm from a copper vapor laser on the output characteristics of a Al2O3:Ti3+ laser. It is shown that the pumping by the long-wave spectral component of the copper vapor radiation is comparable in efficiency with pumping at the wavelength for the shortwave part of the Al2O3:Ti3+ laser generation range. The differential efficiency 26% in the center of the amplification line of the Al2O3:Ti3+ laser at the wavelength 770 nm is obtained.
{"title":"Ti:Al2O3 laser pumped by a copper vapor laser","authors":"A. Kazaryan, M. Kazaryan, S. V. Kruzhalov, Y. Mokrushin, V. A. Parfionov","doi":"10.1117/12.375296","DOIUrl":"https://doi.org/10.1117/12.375296","url":null,"abstract":"Comparative study has been performed of the influence of pumping by two separated wavelengths λ equals 520.6 and λ equals 578.2 nm from a copper vapor laser on the output characteristics of a Al2O3:Ti3+ laser. It is shown that the pumping by the long-wave spectral component of the copper vapor radiation is comparable in efficiency with pumping at the wavelength for the shortwave part of the Al2O3:Ti3+ laser generation range. The differential efficiency 26% in the center of the amplification line of the Al2O3:Ti3+ laser at the wavelength 770 nm is obtained.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115348752","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. Petrosyan, G. Shirinyan, K. Ovanesyan, T. Butaeva, C. Pédrini, C. Dujardin, A. Belsky
Optical transmission and scintillation light yields were measured in Ce3+-doped LuAlO3 and (LuY)AlO3 solid solution single crystals grown by the vertical Bridgman and Czochralski processes. Depending on the growth history, the crystals exhibit dissimilar transmission properties in the UV range. The as-grown color centers possibly responsible for poor transmission properties in the range of Ce3+ emission were characterized by exposing non-activated crystals to 1 Mrad of 60Co gamma-rays. Radiation induced absorption in Ce3+-doped crystals is found to be higher in crystals with good initial transmission properties, while the crystals with high density of as-grown color centers are radiation hard. With time, partial slow-rate natural recovery from the damage was observed at room temperature in all studied crystals. Annealing at higher temperatures or optical bleaching contribute to recombination of gamma-ray induced color centers but affect inconsiderably the as-grown color centers.
{"title":"As-grown color centers and radiation damage in Ce3+ -doped dense rare-earth orthoaluminate scintillators","authors":"A. Petrosyan, G. Shirinyan, K. Ovanesyan, T. Butaeva, C. Pédrini, C. Dujardin, A. Belsky","doi":"10.1117/12.375281","DOIUrl":"https://doi.org/10.1117/12.375281","url":null,"abstract":"Optical transmission and scintillation light yields were measured in Ce3+-doped LuAlO3 and (LuY)AlO3 solid solution single crystals grown by the vertical Bridgman and Czochralski processes. Depending on the growth history, the crystals exhibit dissimilar transmission properties in the UV range. The as-grown color centers possibly responsible for poor transmission properties in the range of Ce3+ emission were characterized by exposing non-activated crystals to 1 Mrad of 60Co gamma-rays. Radiation induced absorption in Ce3+-doped crystals is found to be higher in crystals with good initial transmission properties, while the crystals with high density of as-grown color centers are radiation hard. With time, partial slow-rate natural recovery from the damage was observed at room temperature in all studied crystals. Annealing at higher temperatures or optical bleaching contribute to recombination of gamma-ray induced color centers but affect inconsiderably the as-grown color centers.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124165907","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 resonance fluorescence of a harmonically trapped two- level ion is investigated including effects, which result from the quantized motion. The interaction of a cold trapped ion with a strong laser field is studied in two configurations in which dressed states structure become important, but heating of the ion is unessential.
{"title":"Dressed-states spectroscopy for cooled and trapped atoms","authors":"G. Kryuchkyan, S. B. Manvelyan","doi":"10.1117/12.375276","DOIUrl":"https://doi.org/10.1117/12.375276","url":null,"abstract":"The resonance fluorescence of a harmonically trapped two- level ion is investigated including effects, which result from the quantized motion. The interaction of a cold trapped ion with a strong laser field is studied in two configurations in which dressed states structure become important, but heating of the ion is unessential.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132242793","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}
Various tetraphenylporphyrins (zinc, magnesium, free base) were excited to the upper electronic levels of the Soret band with the second harmonic of a mode-locked Ti-sapphire laser (394 nm). An up-conversion fluorescence set-up with the time resolution of 120 fs was used to measure the decay times of the S2 fluorescence in conjunction with the risetime of the S1 fluorescence. The depopulation of the excited electronic state S2 was studied as a function of the metal ion and the solvent. The lifetimes of the electronic S2 level, measured for ZnTPP and MgTPP in different solvents were (tau) equals 1.4 - 3.4 ps. The depopulation channel from S2 to S1 was studied by measuring simultaneously the decay of S2 and the rise of S1 fluorescence. The rate constant of the process can be correlated to the energy gap between the S2 and S1 levels, which depends on the nature of the metal ions and solvents. The rotational dynamics in the Soret band was also studied by measuring the anisotropy of S2 ---> S0 fluorescence. The anisotropy decay of S2 fluorescence was found to be biexponential, with a fast component around 100 fs and a slow one (t >> 10 ps), attributed to the partial dephasing of the degenerate energy levels of the S2 state and to rotational diffusion, respectively.
{"title":"Direct measurement of S2 -- S0 fluorescence lifetimes and anisotropy of tetraphenylporphyrins","authors":"G. Gurzadyan, T. Tran-Thi, T. Gustavsson","doi":"10.1117/12.375279","DOIUrl":"https://doi.org/10.1117/12.375279","url":null,"abstract":"Various tetraphenylporphyrins (zinc, magnesium, free base) were excited to the upper electronic levels of the Soret band with the second harmonic of a mode-locked Ti-sapphire laser (394 nm). An up-conversion fluorescence set-up with the time resolution of 120 fs was used to measure the decay times of the S2 fluorescence in conjunction with the risetime of the S1 fluorescence. The depopulation of the excited electronic state S2 was studied as a function of the metal ion and the solvent. The lifetimes of the electronic S2 level, measured for ZnTPP and MgTPP in different solvents were (tau) equals 1.4 - 3.4 ps. The depopulation channel from S2 to S1 was studied by measuring simultaneously the decay of S2 and the rise of S1 fluorescence. The rate constant of the process can be correlated to the energy gap between the S2 and S1 levels, which depends on the nature of the metal ions and solvents. The rotational dynamics in the Soret band was also studied by measuring the anisotropy of S2 ---> S0 fluorescence. The anisotropy decay of S2 fluorescence was found to be biexponential, with a fast component around 100 fs and a slow one (t >> 10 ps), attributed to the partial dephasing of the degenerate energy levels of the S2 state and to rotational diffusion, respectively.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125988576","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}
In the present paper it is shown that one can present the porous semiconductor as a set of clusters of silicon atoms surrounded by SiOx, as well as the single crystalline silicon substrate can be considered as an infinite cluster also. The formulae for the estimation of variable porosity of the material (including the value of critical porosity-- the percolation threshold, after which the characteristic phenomena are expected in porous silicon) and the forbidden bandgap value of clusters are suggested as functions of the sizes of nanocrystallites. A new fractal model of pore creation on the surface of a material is proposed also. The cases of semi-spherical, conical (V-groove dielectric isolation technology) and cylindrical (U-groove dielectric isolation technology) are considered. Formulae for the formed surface area S, material porosity p as a function of the depth and fractal dimension are obtained.
{"title":"Fractal modeling of porous semiconductors","authors":"V. Aroutiounian, M.Zh. Ghoolinian","doi":"10.1117/12.375283","DOIUrl":"https://doi.org/10.1117/12.375283","url":null,"abstract":"In the present paper it is shown that one can present the porous semiconductor as a set of clusters of silicon atoms surrounded by SiOx, as well as the single crystalline silicon substrate can be considered as an infinite cluster also. The formulae for the estimation of variable porosity of the material (including the value of critical porosity-- the percolation threshold, after which the characteristic phenomena are expected in porous silicon) and the forbidden bandgap value of clusters are suggested as functions of the sizes of nanocrystallites. A new fractal model of pore creation on the surface of a material is proposed also. The cases of semi-spherical, conical (V-groove dielectric isolation technology) and cylindrical (U-groove dielectric isolation technology) are considered. Formulae for the formed surface area S, material porosity p as a function of the depth and fractal dimension are obtained.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"29 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131809365","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}
We investigate the marriage of two different optical nonlinearities, which allow us to control the operation regimes of an intracavity light generation. Two kinds of cascaded nonlinear optical schemes involved two- and three- Hopf bifurcations are presented.
{"title":"Engineering of optical instabilities by cascaded nonlinearities","authors":"G. Kryuchkyan, Naira Muradyan","doi":"10.1117/12.375303","DOIUrl":"https://doi.org/10.1117/12.375303","url":null,"abstract":"We investigate the marriage of two different optical nonlinearities, which allow us to control the operation regimes of an intracavity light generation. Two kinds of cascaded nonlinear optical schemes involved two- and three- Hopf bifurcations are presented.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"54 16","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120855159","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 short description of optical systems of space astrophysical observatories Orion 1 and Orion 2 is presented. With the help of these observatory-spectrographs, the short wavelength spectrograms, up to 2000 angstroms, of individual stars have been obtained. A concise resume of main scientific results derived from these spectrograms are presented as well.
{"title":"Spectrophotometric observations with the help of space astrophysical observatories ORION 1 and ORION 2","authors":"G. A. Gurzadyan","doi":"10.1117/12.375288","DOIUrl":"https://doi.org/10.1117/12.375288","url":null,"abstract":"A short description of optical systems of space astrophysical observatories Orion 1 and Orion 2 is presented. With the help of these observatory-spectrographs, the short wavelength spectrograms, up to 2000 angstroms, of individual stars have been obtained. A concise resume of main scientific results derived from these spectrograms are presented as well.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"336 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114635791","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}
Soft X-ray radiation from krypton and nitrogen clusters in a supersonic gas jet is studied here. Isolated lines of He- like nitrogen ions in the 1.5 to 3.0 nm wavelengths region and of 7 to 13-charged ions of krypton in the 1.5 to 20 nm region are observed using to 4 to 6 keV electron beam excitation with 50 to 75 mA beam current. The obtained spectra are investigated depending the gas jet flow and excitation parameters.
{"title":"Soft x-ray emission of e-beam-excited clustered supersonic gas jet","authors":"S. A. Ter-Avetisyan, V. Papanyan","doi":"10.1117/12.375294","DOIUrl":"https://doi.org/10.1117/12.375294","url":null,"abstract":"Soft X-ray radiation from krypton and nitrogen clusters in a supersonic gas jet is studied here. Isolated lines of He- like nitrogen ions in the 1.5 to 3.0 nm wavelengths region and of 7 to 13-charged ions of krypton in the 1.5 to 20 nm region are observed using to 4 to 6 keV electron beam excitation with 50 to 75 mA beam current. The obtained spectra are investigated depending the gas jet flow and excitation parameters.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128014877","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 influence of the initial state preparation by an interaction with resonant traveling waves on the anomalous standing wave scattering of a two-level system with magnetic sublevels for arbitrary coherency (1) between the atomic sublevels and (2) between the polarizations of counterpropagating waves is discussed. The potential of the magnetic sublevels and light polarization in the formation of specific types of split initial momentum distributions is pointed out. It is found a new effect of narrowing of the interference fringes of the diffraction pattern taking place at particular case of the initial wave packet splitting involving two translation states, whose momenta differ by two photon momenta, corresponding to the same energy level. It is shown that this narrowing can be combined with the known asymmetric scattering.
{"title":"Role of magnitude sublevels in anomalous standing-wave diffraction of atoms","authors":"A. Ishkhanyan","doi":"10.1117/12.375300","DOIUrl":"https://doi.org/10.1117/12.375300","url":null,"abstract":"The influence of the initial state preparation by an interaction with resonant traveling waves on the anomalous standing wave scattering of a two-level system with magnetic sublevels for arbitrary coherency (1) between the atomic sublevels and (2) between the polarizations of counterpropagating waves is discussed. The potential of the magnetic sublevels and light polarization in the formation of specific types of split initial momentum distributions is pointed out. It is found a new effect of narrowing of the interference fringes of the diffraction pattern taking place at particular case of the initial wave packet splitting involving two translation states, whose momenta differ by two photon momenta, corresponding to the same energy level. It is shown that this narrowing can be combined with the known asymmetric scattering.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129554587","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 quantitative analysis of the mechanism of S- and N-type negative differential conductivity (NDC) of electrons in low-temperature plasma due to the electron-electron interaction (EEI) is presented. It is shown that EEI along with NDC of electrons can initiate the generation of high- frequency domains moving with velocities of the order drift velocity of electrons accompanied in some cases with the discontinuous constriction of positive columns of glow discharges. The estimations show that EEI can be displayed in a large number of gases and gas mixtures; comparisons with experiments and numerous simulations confirm the validity of the proposed theory. The use of powerful spectroscopic diagnostic methods is necessary for the tracing of dynamics excited species needed for elaboration of self-consistent description of NDC of electrons.
{"title":"Theory of the negative differential conductivity of electrons due to electron-electron interaction in low-temperature plasma","authors":"R. V. Chiflikyan","doi":"10.1117/12.375291","DOIUrl":"https://doi.org/10.1117/12.375291","url":null,"abstract":"The quantitative analysis of the mechanism of S- and N-type negative differential conductivity (NDC) of electrons in low-temperature plasma due to the electron-electron interaction (EEI) is presented. It is shown that EEI along with NDC of electrons can initiate the generation of high- frequency domains moving with velocities of the order drift velocity of electrons accompanied in some cases with the discontinuous constriction of positive columns of glow discharges. The estimations show that EEI can be displayed in a large number of gases and gas mixtures; comparisons with experiments and numerous simulations confirm the validity of the proposed theory. The use of powerful spectroscopic diagnostic methods is necessary for the tracing of dynamics excited species needed for elaboration of self-consistent description of NDC of electrons.","PeriodicalId":427427,"journal":{"name":"Atomic and Molecular Spectroscopy","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122498795","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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