I. Balchev, A. Nikolov, N. Stankova, I. Avramova, E. Valcheva, S. Russev, D. Karashanova, I. Kostadinov, J. Mladenoff, S. Kolev, T. Milenov
The phase composition and morphology of nano-dispersed carbon phases obtained by nanosecond laser ablation of microcrystalline graphite target immersed in water were investigated. The second (λSHG= 532 nm) and the third (λTHG= 355 nm) harmonics of a Nd:YAG laser system were used to produce different water colloids of carbon. The values of the laser fluence applied for both wavelengths under the experimental conditions chosen were varied from several J/cm2 to tens of J/cm2 . Raman spectroscopy, X-ray photoelectron spectroscopy and SEM analyses were used to study the carbon target before and after laser treatment and the carbon colloids obtained. The study of the colloids is complemented through X-ray diffraction. A mix of different complex carbon phases and some hydrocarbon polymers (polystyrene predominantly) were found in the colloids.
{"title":"Ablation of graphite in water by Nd:YAG laser","authors":"I. Balchev, A. Nikolov, N. Stankova, I. Avramova, E. Valcheva, S. Russev, D. Karashanova, I. Kostadinov, J. Mladenoff, S. Kolev, T. Milenov","doi":"10.1117/12.2516368","DOIUrl":"https://doi.org/10.1117/12.2516368","url":null,"abstract":"The phase composition and morphology of nano-dispersed carbon phases obtained by nanosecond laser ablation of microcrystalline graphite target immersed in water were investigated. The second (λSHG= 532 nm) and the third (λTHG= 355 nm) harmonics of a Nd:YAG laser system were used to produce different water colloids of carbon. The values of the laser fluence applied for both wavelengths under the experimental conditions chosen were varied from several J/cm2 to tens of J/cm2 . Raman spectroscopy, X-ray photoelectron spectroscopy and SEM analyses were used to study the carbon target before and after laser treatment and the carbon colloids obtained. The study of the colloids is complemented through X-ray diffraction. A mix of different complex carbon phases and some hydrocarbon polymers (polystyrene predominantly) were found in the colloids.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"15 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132285763","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}
N. Berberova, P. Sharlandjiev, D. Nazarova, L. Nedelchev
In this paper we analyze the optical response of azopolymer (poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido] -1,2-ethan-ediyl, sodium salt]), shortly denoted as PAZO. The photoinduced birefringence of this material has a potential for polarization holographic recording. We consider thin PAZO layers with embedded TiO2 spherical particles. This is a numeric simulation motivated by the search of photoinduced birefringence enhancement in azopolymer layers. The scattering of a single particle in the dye-polymer matrix is calculated using the exact vector Maxwell equations. The particles are treated as ensemble of non-aggregated spheres with normal distribution of sizes, characterized by the mean radius /4. Multiple scattering by individual particles is ignored. The refractive index of the PAZO matrix at 442 nm has a complex value (due to absorption) as we have determined it from experimental spectrophotometric data. The 442 nm wavelength is commonly used for recording polarization holographic gratings in azopolymer materials. Embedded TiO2 spheres with mean radius from 10 to 80 nm are considered. The angular dependences of all the scattering matrix elements, which describe the optical response of the composite layers, are estimated.
{"title":"Optical response of azopolymer (PAZO) layers doped with TiO2 nanoparticles","authors":"N. Berberova, P. Sharlandjiev, D. Nazarova, L. Nedelchev","doi":"10.1117/12.2516751","DOIUrl":"https://doi.org/10.1117/12.2516751","url":null,"abstract":"In this paper we analyze the optical response of azopolymer (poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido] -1,2-ethan-ediyl, sodium salt]), shortly denoted as PAZO. The photoinduced birefringence of this material has a potential for polarization holographic recording. We consider thin PAZO layers with embedded TiO2 spherical particles. This is a numeric simulation motivated by the search of photoinduced birefringence enhancement in azopolymer layers. The scattering of a single particle in the dye-polymer matrix is calculated using the exact vector Maxwell equations. The particles are treated as ensemble of non-aggregated spheres with normal distribution of sizes, characterized by the mean radius /4. Multiple scattering by individual particles is ignored. The refractive index of the PAZO matrix at 442 nm has a complex value (due to absorption) as we have determined it from experimental spectrophotometric data. The 442 nm wavelength is commonly used for recording polarization holographic gratings in azopolymer materials. Embedded TiO2 spheres with mean radius from 10 to 80 nm are considered. The angular dependences of all the scattering matrix elements, which describe the optical response of the composite layers, are estimated.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133544707","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 work we have investigated the in vivo effect of tissue temperature and laser parameters on the quantum efficiency of laser-induced photodissociation of oxyhemoglobin (HbO2) in cutaneous blood vessels by measuring the change in the oxygen saturation of arterial blood. Arterial oxygen saturation (SaO2) was measured using the method of fingertip pulse oximetry. It is shown that there is a local decrease in the local oxygen saturation upon laser irradiation by approximately 10% . Raising the local temperature of the skin tissue up to 42°C leads to an increase in the quantum efficiency of the photodissociation of HbO2 by approximately 1,5% upon irradiation with a wavelength of 860 nm. The obtained results can be used in the clinical phototherapy practice.
{"title":"Effect of tissue temperature and radiation parameters on the quantum efficiency of photodissociation of oxyhemoglobin in cutaneous blood vessels","authors":"A. Gisbrecht, S. Mamilov, S. S. Esman","doi":"10.1117/12.2516163","DOIUrl":"https://doi.org/10.1117/12.2516163","url":null,"abstract":"In the present work we have investigated the in vivo effect of tissue temperature and laser parameters on the quantum efficiency of laser-induced photodissociation of oxyhemoglobin (HbO2) in cutaneous blood vessels by measuring the change in the oxygen saturation of arterial blood. Arterial oxygen saturation (SaO2) was measured using the method of fingertip pulse oximetry. It is shown that there is a local decrease in the local oxygen saturation upon laser irradiation by approximately 10% . Raising the local temperature of the skin tissue up to 42°C leads to an increase in the quantum efficiency of the photodissociation of HbO2 by approximately 1,5% upon irradiation with a wavelength of 860 nm. The obtained results can be used in the clinical phototherapy practice.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122329705","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}
P. Todorov, J. C. de Aquino Carvalho, I. Maurin, A. Laliotis, D. Bloch
The isotropic Maxwell-Boltzmann (M-B) velocity distribution is the accepted standard for a gas at thermal equilibrium, with the Doppler width considered to deliver a very precise measurement of the temperature. Nevertheless, the physical nature of the surface, and the atom-surface interaction, in its long-range (van der Waals type) regime as well as in its short-range regime leading to adsorption/desorption mechanisms, are far from the ideal situation describing the foundation of gas kinetics. Through the development of vapor spectroscopy at an interface, a high sensitivity to atoms flying nearly parallel to the gas interface is obtained, and deviations to M-B distribution could have observable effects, even affecting the ultimate limits to resolution. We report here on the development of an experiment involving a dedicated set-up of spatially-separated pump-probe experiment in a narrow cell. A first series of investigation could not evidence a deviation for Cs atom velocities at a nearly grazing incidence (typically 1.5 -5°). We discuss various technical improvements to increase the sensitivity to atoms flying parallel to the surface, along with specific spectroscopic information that may be collected. Alternately, the comparison of standard selective reflection spectroscopy with simultaneous volume spectroscopy may be a source of complementary information. At last, we discuss how the Boltzmann energy distribution, among molecular or atomic levels, may become sensitive to specific thermal exchanges at the surface, in an equilibrium situation.
{"title":"Search for deviations from the ideal Maxwell-Boltzmann distribution for a gas at an interface","authors":"P. Todorov, J. C. de Aquino Carvalho, I. Maurin, A. Laliotis, D. Bloch","doi":"10.1117/12.2519719","DOIUrl":"https://doi.org/10.1117/12.2519719","url":null,"abstract":"The isotropic Maxwell-Boltzmann (M-B) velocity distribution is the accepted standard for a gas at thermal equilibrium, with the Doppler width considered to deliver a very precise measurement of the temperature. Nevertheless, the physical nature of the surface, and the atom-surface interaction, in its long-range (van der Waals type) regime as well as in its short-range regime leading to adsorption/desorption mechanisms, are far from the ideal situation describing the foundation of gas kinetics. Through the development of vapor spectroscopy at an interface, a high sensitivity to atoms flying nearly parallel to the gas interface is obtained, and deviations to M-B distribution could have observable effects, even affecting the ultimate limits to resolution. We report here on the development of an experiment involving a dedicated set-up of spatially-separated pump-probe experiment in a narrow cell. A first series of investigation could not evidence a deviation for Cs atom velocities at a nearly grazing incidence (typically 1.5 -5°). We discuss various technical improvements to increase the sensitivity to atoms flying parallel to the surface, along with specific spectroscopic information that may be collected. Alternately, the comparison of standard selective reflection spectroscopy with simultaneous volume spectroscopy may be a source of complementary information. At last, we discuss how the Boltzmann energy distribution, among molecular or atomic levels, may become sensitive to specific thermal exchanges at the surface, in an equilibrium situation.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116495781","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. Daskalova, I. Bliznakova, A. Trifonov, I. Buchvarov, C. R. Nathala, W. Husinsky
The creation of microporous surface modification of chitosan thin films irradiated by ultrashort laser pulses are studied. For this purpose, chitosan substrates were treated by using an amplified Ti:sapphire laser system at 800 nm central wavelength with 30 fs and 150 fs pulse duration and repetition rate 1 kHz and 50 Hz, respectively. Formation of surface modifications for both cases (30 fs and 150 fs) after femtosecond laser irradiation were observed. The threshold values for single-pulse (N = 1) and multi-pulse (N > 1) modification were evaluated by studying the linear relationship between the squared crater diameter D2 and the logarithm of the laser fluence (F) for N = 1, 2, 5, 10, 20, 30 and 50 number of laser pulses. The coefficient of incubation ξ, a major parameter in the process of surface modification and ablation of materials also was calculated for multi - pulse fluence threshold estimation by power - law relationship Fth (N) = Fth (1) Nξ-1, where N is the number of applied laser pulses. The surface properties of chitosan based thin films before and after femtosecond laser irradiation were investigated. The aim of this work is to determine the optimal morphological characteristics of the created structures for tailoring of protein adsorption and cell behavior.
{"title":"Morphological characterization of chitosan biopolymer thin films modified via fs irradiation and its potential application as functional surfaces in regenerative medicine","authors":"A. Daskalova, I. Bliznakova, A. Trifonov, I. Buchvarov, C. R. Nathala, W. Husinsky","doi":"10.1117/12.2262679","DOIUrl":"https://doi.org/10.1117/12.2262679","url":null,"abstract":"The creation of microporous surface modification of chitosan thin films irradiated by ultrashort laser pulses are studied. For this purpose, chitosan substrates were treated by using an amplified Ti:sapphire laser system at 800 nm central wavelength with 30 fs and 150 fs pulse duration and repetition rate 1 kHz and 50 Hz, respectively. Formation of surface modifications for both cases (30 fs and 150 fs) after femtosecond laser irradiation were observed. The threshold values for single-pulse (N = 1) and multi-pulse (N > 1) modification were evaluated by studying the linear relationship between the squared crater diameter D2 and the logarithm of the laser fluence (F) for N = 1, 2, 5, 10, 20, 30 and 50 number of laser pulses. The coefficient of incubation ξ, a major parameter in the process of surface modification and ablation of materials also was calculated for multi - pulse fluence threshold estimation by power - law relationship Fth (N) = Fth (1) Nξ-1, where N is the number of applied laser pulses. The surface properties of chitosan based thin films before and after femtosecond laser irradiation were investigated. The aim of this work is to determine the optimal morphological characteristics of the created structures for tailoring of protein adsorption and cell behavior.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"8 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120854988","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. G. Tagiev, O. Tagiev, I. Huseynov, K. Allahverdiyev
Thiogallate compounds represented by general formula MGa2S4 [where M- Ca+2, Ba+2, Sr+2, Pb+2, Eu+2, Eu+3, (Na+1La+3) and (Na+1Ce+3)] are highly effective electro-luminescence and laser materials. These materials were first synthesized in 1971 and studied by many groups due to their possible applicability in opto-, and quantum- electronics. Forbidden band gap (ΔE) at room temperature (RT) for these materials varies in a wide range from ΔE ∼ eV for CaGa2S4 to ∼ 2.32 eV for Ca4Ga2S7. In the present paper the results of structural properties and photoluminescence (PL) measurements (temperature range of 77 – 300 K) of melt grown Ca4Ga2S7 single crystals doped with 5 at% of rare earth (RE) Eu2+ (Ca4Ga2S7 : Eu2+) are described for the first time. It is shown that, broadband PL with a maximum at 660 nm is caused with intra shell transitions 4f65d - 4f7(8S7/2) of Eu2+ ions.
{"title":"Synthesis and characterization of rare earth doped ternary chalcogenide semiconductors: effective electro-luminescence and laser materials","authors":"A. Pashayev, B. G. Tagiev, O. Tagiev, I. Huseynov, K. Allahverdiyev","doi":"10.1117/12.2260889","DOIUrl":"https://doi.org/10.1117/12.2260889","url":null,"abstract":"Thiogallate compounds represented by general formula MGa2S4 [where M- Ca+2, Ba+2, Sr+2, Pb+2, Eu+2, Eu+3, (Na+1La+3) and (Na+1Ce+3)] are highly effective electro-luminescence and laser materials. These materials were first synthesized in 1971 and studied by many groups due to their possible applicability in opto-, and quantum- electronics. Forbidden band gap (ΔE) at room temperature (RT) for these materials varies in a wide range from ΔE ∼ eV for CaGa2S4 to ∼ 2.32 eV for Ca4Ga2S7. In the present paper the results of structural properties and photoluminescence (PL) measurements (temperature range of 77 – 300 K) of melt grown Ca4Ga2S7 single crystals doped with 5 at% of rare earth (RE) Eu2+ (Ca4Ga2S7 : Eu2+) are described for the first time. It is shown that, broadband PL with a maximum at 660 nm is caused with intra shell transitions 4f65d - 4f7(8S7/2) of Eu2+ ions.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122371650","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}
N. Antonopoulou-Athera, E. Profitis, E. Chatzitheodoridis, A. Terlixi, M. Doulgerides, A. Serafetinides
The present work aims to further investigate the effects of laser cleaning of the burnt Parthenis' paintings, and to the development of a restoration procedure with the use of pulsed lasers, in combination with several characterisation methods. The evaluation of different types of laser, such as Nd:YAG laser with five harmonics, Er:YAG laser, and CO2 using various fluences on different areas of the painting has been already performed and published1. In this work, and taking into account the previous results as well as the respective literature2, 3, untreated parts of the burnt paintings were cleaned with the optimum combination of laser parameters. The cleaning process was thoroughly examined with X-ray diffraction (XRD). In addition, the stratified layers of the paint were determined giving valuable information about the inner layers of the paintings. In the previous published work1, the optimum cleaning parameters have been assessed with the assumption that one single laser will be used to clean the entire surface of both burnt paintings. Nevertheless, thickness differences of the layers of the applied paint lead to the necessity of investigating the use of multiple lasers and of different parameters according to the required degree of cleaning. Therefore, restoration procedures based on multiple lasers or on a single laser, with varying parameters, are evaluated. One more technique to be introduced here is the visual digital reconstruction of the burnt paintings, which has the potential to provide an estimate of the degree of the required treatment.
{"title":"Investigation of laser cleaning procedures for the restoration of burnt paintings","authors":"N. Antonopoulou-Athera, E. Profitis, E. Chatzitheodoridis, A. Terlixi, M. Doulgerides, A. Serafetinides","doi":"10.1117/12.2262493","DOIUrl":"https://doi.org/10.1117/12.2262493","url":null,"abstract":"The present work aims to further investigate the effects of laser cleaning of the burnt Parthenis' paintings, and to the development of a restoration procedure with the use of pulsed lasers, in combination with several characterisation methods. The evaluation of different types of laser, such as Nd:YAG laser with five harmonics, Er:YAG laser, and CO2 using various fluences on different areas of the painting has been already performed and published1. In this work, and taking into account the previous results as well as the respective literature2, 3, untreated parts of the burnt paintings were cleaned with the optimum combination of laser parameters. The cleaning process was thoroughly examined with X-ray diffraction (XRD). In addition, the stratified layers of the paint were determined giving valuable information about the inner layers of the paintings. In the previous published work1, the optimum cleaning parameters have been assessed with the assumption that one single laser will be used to clean the entire surface of both burnt paintings. Nevertheless, thickness differences of the layers of the applied paint lead to the necessity of investigating the use of multiple lasers and of different parameters according to the required degree of cleaning. Therefore, restoration procedures based on multiple lasers or on a single laser, with varying parameters, are evaluated. One more technique to be introduced here is the visual digital reconstruction of the burnt paintings, which has the potential to provide an estimate of the degree of the required treatment.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124301963","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}
One of the most widespread optical methods used in biophotonics is the pulse oximetry, which is based on the measurement of light-modulated pulse wave of blood. This is a non-invasive, objective method for evaluation of the blood supply. Recently it has become very popular in dental medicine for the measurement of the condition of pulp microcirculation. The aim of our research is to evaluate the possibilities of pulse oximetry for estimation the pulp microcirculation in intact teeth among young patients. Results obtained clearly show that this method can be applied to assess the pulp condition and could be used in clinical practice in combination with other diagnostic methods.
{"title":"Pulse oximetry as a diagnostic tool in dental medicine","authors":"D. Kosturkov, T. Uzunov, P. Uzunova","doi":"10.1117/12.2262267","DOIUrl":"https://doi.org/10.1117/12.2262267","url":null,"abstract":"One of the most widespread optical methods used in biophotonics is the pulse oximetry, which is based on the measurement of light-modulated pulse wave of blood. This is a non-invasive, objective method for evaluation of the blood supply. Recently it has become very popular in dental medicine for the measurement of the condition of pulp microcirculation. The aim of our research is to evaluate the possibilities of pulse oximetry for estimation the pulp microcirculation in intact teeth among young patients. Results obtained clearly show that this method can be applied to assess the pulp condition and could be used in clinical practice in combination with other diagnostic methods.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"10226 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129972101","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}
Three new conical intersections S0/S1 (cis-anti, trans-syn and trans-anti) were fond which mediate the processes of photo-induced formation of cyclobutane thymine dimers. Their structures were optimized at the CASSCF(2,2) (Complete Active Space Self Consistent Field method) level of theory with the minimal bases set STO-3G*. The geometries were explored with respect to their structural and electron features. The found conical intersections S0/S1 give a clear indication that they could be included in the internal conversions of the 1ππ* excited states of the stacked dimers to cyclobutane photodimers and vice versa.
{"title":"Conical intersections S0/S1 of thymine mediating the non-radiative photodestruction of cyclobutane dimers: a CASSCF level study","authors":"P. Kancheva, V. Delchev","doi":"10.1117/12.2263479","DOIUrl":"https://doi.org/10.1117/12.2263479","url":null,"abstract":"Three new conical intersections S0/S1 (cis-anti, trans-syn and trans-anti) were fond which mediate the processes of photo-induced formation of cyclobutane thymine dimers. Their structures were optimized at the CASSCF(2,2) (Complete Active Space Self Consistent Field method) level of theory with the minimal bases set STO-3G*. The geometries were explored with respect to their structural and electron features. The found conical intersections S0/S1 give a clear indication that they could be included in the internal conversions of the 1ππ* excited states of the stacked dimers to cyclobutane photodimers and vice versa.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"10226 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130001983","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 work we investigate the relation of the polarization moments having different ranks with the tensor components which form the observable integral CPT signal, in the presence of a stray magnetic field. A numerical experiment with parameters close to the real ones is performed, using a program based on the irreducible tensor operator formalism1. The integral fluorescent signal is calculated for the non-polarized fluorescence at different laser power excitation. Detailed analysis of the numerical solutions for all tensor components which describe population and alignment allows visualizing the dynamics of their behavior in dependence on the experimental geometry and laboratory magnetic field B′. The dependence of population f00, longitudinal f02 and transverse f22 alignment in the presence of transverse magnetic field is investigated. The shape and sign of the resonance change with laser power.
{"title":"Contribution of the polarization moments of different rank to the integral CPT signal","authors":"E. Taskova, E. Alipieva, G. Todorov","doi":"10.1117/12.2261673","DOIUrl":"https://doi.org/10.1117/12.2261673","url":null,"abstract":"In the present work we investigate the relation of the polarization moments having different ranks with the tensor components which form the observable integral CPT signal, in the presence of a stray magnetic field. A numerical experiment with parameters close to the real ones is performed, using a program based on the irreducible tensor operator formalism1. The integral fluorescent signal is calculated for the non-polarized fluorescence at different laser power excitation. Detailed analysis of the numerical solutions for all tensor components which describe population and alignment allows visualizing the dynamics of their behavior in dependence on the experimental geometry and laboratory magnetic field B′. The dependence of population f00, longitudinal f02 and transverse f22 alignment in the presence of transverse magnetic field is investigated. The shape and sign of the resonance change with laser power.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130096281","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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