Pub Date : 2026-03-10DOI: 10.1016/j.jqsrt.2026.109908
Daniela Alvarado-Jiménez, Nicola Tasinato, Richard Brownsword, Damien Weidmann, Roberto Buizza, Keith P. Shine
Hydrofluorocarbons (HFCs) are used as substitutes for ozone-depleting substances regulated under the Montreal Protocol. While having zero ozone depletion potential, HFCs strongly absorb infrared (IR) radiation, making them potent greenhouse gases. Vibrational modes associated with C–F stretching absorb strongly within the atmospheric window (750–1250 cm−1), contributing substantially to radiative forcing. The low-frequency region (< 500 cm−1), which accounts for approximately 16% of the Earth’s thermal emission, has however remained largely unexplored mainly due to instrumental challenges. Here, we present the first experimental measurements of IR absorption cross-sections in the 150–500 cm−1 range for HFC-236fa, HFC-245fa, and HFC-43-10mee - three industrially relevant compounds with high global warming potentials (GWPs). The spectra were recorded at the Rutherford Appleton Laboratory using a high-resolution Fourier-transform infrared (FTIR) spectrometer in the temperature range between 225 and 298 K at resolution of 0.25 cm-1. In addition, IR cross section spectra were simulated through quantum chemical (QC) calculations including a non-empirical treatment of anharmonic effects.
{"title":"Low-frequency contributions in the radiative efficiencies of HFC-236fa, HFC-245fa and HFC-43-10mee over the 225 – 298 K temperature range","authors":"Daniela Alvarado-Jiménez, Nicola Tasinato, Richard Brownsword, Damien Weidmann, Roberto Buizza, Keith P. Shine","doi":"10.1016/j.jqsrt.2026.109908","DOIUrl":"https://doi.org/10.1016/j.jqsrt.2026.109908","url":null,"abstract":"Hydrofluorocarbons (HFCs) are used as substitutes for ozone-depleting substances regulated under the Montreal Protocol. While having zero ozone depletion potential, HFCs strongly absorb infrared (IR) radiation, making them potent greenhouse gases. Vibrational modes associated with C–F stretching absorb strongly within the atmospheric window (750–1250 cm<ce:sup loc=\"post\">−1</ce:sup>), contributing substantially to radiative forcing. The low-frequency region (<mml:math altimg=\"si1.svg\" display=\"inline\"><mml:mo><</mml:mo></mml:math> 500 cm<ce:sup loc=\"post\">−1</ce:sup>), which accounts for approximately 16% of the Earth’s thermal emission, has however remained largely unexplored mainly due to instrumental challenges. Here, we present the first experimental measurements of IR absorption cross-sections in the 150–500 cm<ce:sup loc=\"post\">−1</ce:sup> range for HFC-236fa, HFC-245fa, and HFC-43-10mee - three industrially relevant compounds with high global warming potentials (GWPs). The spectra were recorded at the Rutherford Appleton Laboratory using a high-resolution Fourier-transform infrared (FTIR) spectrometer in the temperature range between 225 and 298 K at resolution of 0.25 cm<mml:math altimg=\"si2.svg\" display=\"inline\"><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mtext>-1</mml:mtext></mml:mrow></mml:msup></mml:math>. In addition, IR cross section spectra were simulated through quantum chemical (QC) calculations including a non-empirical treatment of anharmonic effects.","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"104 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-06DOI: 10.1016/j.jqsrt.2026.109897
Kameswara S. Vinjamuri, Marco Vountas, Vladimir Rozanov, Luca Lelli, Hartmut Boesch, John P. Burrows
This study investigates the sensitivity of satellite-based brightness temperature measurements at 3.74, 10.85, and 12.00 μm with respect to the identification of water, ice, and mixed-phase clouds (MPC). Radiative transfer simulations computed by SCIATRAN reveal that the directional brightness temperature difference at 3.74 μm (ΔBT3.74), which is dependent on scattering, enables water clouds and MPC separation from ice clouds. For water clouds and MPC, ΔBT3.74 typically exceeds 2 K, whereas for ice clouds it remains below 2 K. To separate MPC from water clouds, we introduce the Liquid Cloud Probability Index (LCPI) based on cloud top temperature and absorption differences between water and ice at 10.85 and 12.00 μm. LCPI values generally exceed 0.4 for water clouds but fall below 0.4 for many MPC cases. The ΔBT3.74 and LCPI approach is validated using the Sea and Land Surface Temperature Radiometer (SLSTR) dual-view data collocated with the 2B-CLDCLASS-LIDAR cloud phase product, showing over 90% accuracy in water and ice phase classification, and approximately 60% for MPC. This dual-view, multi-channel method enhances the detection of cloud phases, offering improved results for brightness temperature measurements.
{"title":"Cloud phase classification using SLSTR measured brightness temperatures at 3.74, 10.85, 12.00 [formula omitted]m","authors":"Kameswara S. Vinjamuri, Marco Vountas, Vladimir Rozanov, Luca Lelli, Hartmut Boesch, John P. Burrows","doi":"10.1016/j.jqsrt.2026.109897","DOIUrl":"https://doi.org/10.1016/j.jqsrt.2026.109897","url":null,"abstract":"This study investigates the sensitivity of satellite-based brightness temperature measurements at 3.74, 10.85, and 12.00 <mml:math altimg=\"si35.svg\" display=\"inline\"><mml:mi mathvariant=\"normal\">μ</mml:mi></mml:math>m with respect to the identification of water, ice, and mixed-phase clouds (MPC). Radiative transfer simulations computed by SCIATRAN reveal that the directional brightness temperature difference at 3.74 <mml:math altimg=\"si35.svg\" display=\"inline\"><mml:mi mathvariant=\"normal\">μ</mml:mi></mml:math>m (<mml:math altimg=\"si38.svg\" display=\"inline\"><mml:mrow><mml:mi>Δ</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">BT</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>.</mml:mo><mml:mn>74</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>), which is dependent on scattering, enables water clouds and MPC separation from ice clouds. For water clouds and MPC, <mml:math altimg=\"si38.svg\" display=\"inline\"><mml:mrow><mml:mi>Δ</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">BT</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>.</mml:mo><mml:mn>74</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> typically exceeds 2 K, whereas for ice clouds it remains below 2 K. To separate MPC from water clouds, we introduce the Liquid Cloud Probability Index (LCPI) based on cloud top temperature and absorption differences between water and ice at 10.85 and 12.00 <mml:math altimg=\"si35.svg\" display=\"inline\"><mml:mi mathvariant=\"normal\">μ</mml:mi></mml:math>m. LCPI values generally exceed 0.4 for water clouds but fall below 0.4 for many MPC cases. The <mml:math altimg=\"si38.svg\" display=\"inline\"><mml:mrow><mml:mi>Δ</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">BT</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>.</mml:mo><mml:mn>74</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> and LCPI approach is validated using the Sea and Land Surface Temperature Radiometer (SLSTR) dual-view data collocated with the 2B-CLDCLASS-LIDAR cloud phase product, showing over 90% accuracy in water and ice phase classification, and approximately 60% for MPC. This dual-view, multi-channel method enhances the detection of cloud phases, offering improved results for brightness temperature measurements.","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"6 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147392774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
26 new energy levels (7 of even, 19 of odd parity) of Pr I were discovered using laser induced fluorescence (LIF) spectroscopy. Values of the magnetic hyperfine interaction constants A of these levels are presented. 57 known but up to now unclassified lines could be classified as transitions to the new levels. Moreover, 77 lines which were never mentioned in the literature but could be identified in our FT spectra, are classified. Finally, 62 other lines could be detected either as excitation or fluorescence channels, but too weak to appear in the FT spectra. For some lines the classification given in the literature appeared to be erroneous.
{"title":"Hyperfine structure investigation of spectral lines of the praseodymium atom in the visible spectral region","authors":"Günay Başar , Gönül Başar , L. Windholz , G.H. Guthöhrlein","doi":"10.1016/j.jqsrt.2025.109799","DOIUrl":"10.1016/j.jqsrt.2025.109799","url":null,"abstract":"<div><div>26 new energy levels (7 of even, 19 of odd parity) of Pr I were discovered using laser induced fluorescence (LIF) spectroscopy. Values of the magnetic hyperfine interaction constants <em>A</em> of these levels are presented. 57 known but up to now unclassified lines could be classified as transitions to the new levels. Moreover, 77 lines which were never mentioned in the literature but could be identified in our FT spectra, are classified. Finally, 62 other lines could be detected either as excitation or fluorescence channels, but too weak to appear in the FT spectra. For some lines the classification given in the literature appeared to be erroneous.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109799"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-11-21DOI: 10.1016/j.jqsrt.2025.109760
Safae Nejjari , Amine Ben Daoued , Frédéric Bernardin , Christophe Debain , Philippe Samuel Heritier
One of the major challenges in smart farming is the dust suspension during operations. Optical sensors embedded in agricultural machines and robots become less effective under such conditions, which compromises the accuracy of measurements and consequently the decision-making process. This study represents a comparative analysis of light transmission models under different configurations, from the Beer–Lambert model to different order scattering models, to assess the effectiveness of each model in different scenarios. This comparison is based on the simulation of a transmissiometer system, operating in a homogeneous dusty medium, consisting of suspended mineral dust particles. The evaluation includes the quantification of relative errors between various models across different optical depth values, sensor fields of view, and source divergence angles. Single, Double, Triple, Quadruple, and Multiple Scattering models were also considered in the quantitative comparison, to identify the conditions under which each model provides sufficient accuracy. Additionally, the influence of different scattering phase functions was investigated. The results highlight that the choice of scattering phase function significantly affects the relative errors, especially at angles close to the main propagation axis. The goal of this classification is to determine scenarios where simplified models can be employed for real-time monitoring, as increasing the order of scattering significantly raises the computational cost, making them less suitable for such applications. This classification helps establish a trade-off between physical accuracy and computational efficiency.
{"title":"Inter-comparison of different order-scattering models for accurate sensing in dusty conditions","authors":"Safae Nejjari , Amine Ben Daoued , Frédéric Bernardin , Christophe Debain , Philippe Samuel Heritier","doi":"10.1016/j.jqsrt.2025.109760","DOIUrl":"10.1016/j.jqsrt.2025.109760","url":null,"abstract":"<div><div>One of the major challenges in smart farming is the dust suspension during operations. Optical sensors embedded in agricultural machines and robots become less effective under such conditions, which compromises the accuracy of measurements and consequently the decision-making process. This study represents a comparative analysis of light transmission models under different configurations, from the Beer–Lambert model to different order scattering models, to assess the effectiveness of each model in different scenarios. This comparison is based on the simulation of a transmissiometer system, operating in a homogeneous dusty medium, consisting of suspended mineral dust particles. The evaluation includes the quantification of relative errors between various models across different optical depth values, sensor fields of view, and source divergence angles. Single, Double, Triple, Quadruple, and Multiple Scattering models were also considered in the quantitative comparison, to identify the conditions under which each model provides sufficient accuracy. Additionally, the influence of different scattering phase functions was investigated. The results highlight that the choice of scattering phase function significantly affects the relative errors, especially at angles close to the main propagation axis. The goal of this classification is to determine scenarios where simplified models can be employed for real-time monitoring, as increasing the order of scattering significantly raises the computational cost, making them less suitable for such applications. This classification helps establish a trade-off between physical accuracy and computational efficiency.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109760"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145567209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing a fast and accurate radiative transfer calculation method is vital in modeling light propagation in biological tissues. We present a novel acceleration scheme for three-dimensional time-dependent radiative transfer simulation. In biological tissues, required angular resolutions for anisotropic radiation fields sensitively depend on spatial positions. Our new scheme changes the angular resolutions with the positions automatically based on local anisotropies of the radiation fields using the spherical Haar wavelet basis function. We apply the new code to simulations of light propagation in a box of polyurethane phantom mimicking biological tissue. We show that the new scheme achieves the acceleration of a factor of at most and on average compared to a simulation with the constant angular resolution while its accuracy keeps the same level. We find that the acceleration becomes more noticeable if low-angular resolution areas spread with time according as the diffuse radiation dominates. As the result of the fewer required angular bins, we find that the new code has the potential to reduce the memory use to at the maximum. Thus, our new scheme also has the advantage from the viewpoint of computational resources. We note that our new scheme is applicable not only to steady-state media but also to scenarios where the physical state of matter changes dynamically. Our new scheme will be a powerful tool to perform radiative transfer simulations of more than a thousand models which must be important in developing machine learning models.
{"title":"Adaptive angular resolution for time-dependent radiative transfer simulations based on local radiation field anisotropy","authors":"Makito Abe , Hidenobu Yajima , Masayuki Umemura , Yoko Hoshi","doi":"10.1016/j.jqsrt.2026.109820","DOIUrl":"10.1016/j.jqsrt.2026.109820","url":null,"abstract":"<div><div>Developing a fast and accurate radiative transfer calculation method is vital in modeling light propagation in biological tissues. We present a novel acceleration scheme for three-dimensional time-dependent radiative transfer simulation. In biological tissues, required angular resolutions for anisotropic radiation fields sensitively depend on spatial positions. Our new scheme changes the angular resolutions with the positions automatically based on local anisotropies of the radiation fields using the spherical Haar wavelet basis function. We apply the new code to simulations of light propagation in a box of polyurethane phantom mimicking biological tissue. We show that the new scheme achieves the acceleration of a factor of <span><math><mrow><mo>∼</mo><mn>8</mn></mrow></math></span> at most and <span><math><mrow><mo>∼</mo><mn>3</mn></mrow></math></span> on average compared to a simulation with the constant angular resolution while its accuracy keeps the same level. We find that the acceleration becomes more noticeable if low-angular resolution areas spread with time according as the diffuse radiation dominates. As the result of the fewer required angular bins, we find that the new code has the potential to reduce the memory use to <span><math><mrow><mo>∼</mo><mn>20</mn><mtext>%</mtext></mrow></math></span> at the maximum. Thus, our new scheme also has the advantage from the viewpoint of computational resources. We note that our new scheme is applicable not only to steady-state media but also to scenarios where the physical state of matter changes dynamically. Our new scheme will be a powerful tool to perform radiative transfer simulations of more than a thousand models which must be important in developing machine learning models.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"352 ","pages":"Article 109820"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-11DOI: 10.1016/j.jqsrt.2025.109791
Augusto García-Valenzuela, Nadia E. Álvarez-Chávez, Anays Acevedo-Barrera
We study the applicability of the Arago-Biot mixing formula to calculate the effective refractive index of particle suspensions using the anomalous diffraction approximation, when the size of the particles is comparable to the wavelength of radiation. Interest in this mixing formula stems from the fact that it does not require knowledge of the particles' size or shape. Thus, it can be useful for determining the refractive index of particles in suspension of size comparable to the wavelength of radiation, regardless of their shape or size distribution. We present an analysis and graphs in the refractive-index-contrast versus size-parameter 2D space of the error of the Arago-Biot mixing formula and the error of using this mixing formula to infer the refractive index of particles in suspension. We consider non-absorbing and absorbing particles. The results obtained demonstrate the viability of inferring the refractive index of particles in suspension with accuracy in the second decimal place by reducing the refracting index contrast with the matrix medium for particles comparable to the wavelength of light.
{"title":"Applicability of the Arago-Biot mixing formula to the effective refractive index of particle suspensions","authors":"Augusto García-Valenzuela, Nadia E. Álvarez-Chávez, Anays Acevedo-Barrera","doi":"10.1016/j.jqsrt.2025.109791","DOIUrl":"10.1016/j.jqsrt.2025.109791","url":null,"abstract":"<div><div>We study the applicability of the Arago-Biot mixing formula to calculate the effective refractive index of particle suspensions using the anomalous diffraction approximation, when the size of the particles is comparable to the wavelength of radiation. Interest in this mixing formula stems from the fact that it does not require knowledge of the particles' size or shape. Thus, it can be useful for determining the refractive index of particles in suspension of size comparable to the wavelength of radiation, regardless of their shape or size distribution. We present an analysis and graphs in the refractive-index-contrast versus size-parameter 2D space of the error of the Arago-Biot mixing formula and the error of using this mixing formula to infer the refractive index of particles in suspension. We consider non-absorbing and absorbing particles. The results obtained demonstrate the viability of inferring the refractive index of particles in suspension with accuracy in the second decimal place by reducing the refracting index contrast with the matrix medium for particles comparable to the wavelength of light.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109791"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-17DOI: 10.1016/j.jqsrt.2025.109795
Zhaoying Chen , Yuhang Ge , Wenhao Xia , Min Wang , Liangyu Huang , Yaming Zou , Baoren Wei , Xiang Gao , Ke Yao
Spectra of Sr-like Sn, Xe, La, Pr, Nd, and Sm ions in the wavelength range of 200–600 nm were measured using an electron beam ion trap. A total of thirty four magnetic dipole transition lines were identified with twenty four lines newly assigned. Theoretical calculations were performed using the multi-configuration Dirac–Hartree–Fock and relativistic configuration interaction methods, incorporating the Breit interaction and the dominant quantum electrodynamics effects. The calculated results show good agreement with experiment, with an average deviation below 1.0%. The experimental spectra reported provide reliable reference data for further studies.
{"title":"Forbidden lines in highly charged strontium-like ions","authors":"Zhaoying Chen , Yuhang Ge , Wenhao Xia , Min Wang , Liangyu Huang , Yaming Zou , Baoren Wei , Xiang Gao , Ke Yao","doi":"10.1016/j.jqsrt.2025.109795","DOIUrl":"10.1016/j.jqsrt.2025.109795","url":null,"abstract":"<div><div>Spectra of Sr-like Sn<span><math><msup><mrow></mrow><mrow><mn>12</mn><mo>+</mo></mrow></msup></math></span>, Xe<span><math><msup><mrow></mrow><mrow><mn>16</mn><mo>+</mo></mrow></msup></math></span>, La<span><math><msup><mrow></mrow><mrow><mn>19</mn><mo>+</mo></mrow></msup></math></span>, Pr<span><math><msup><mrow></mrow><mrow><mn>21</mn><mo>+</mo></mrow></msup></math></span>, Nd<span><math><msup><mrow></mrow><mrow><mn>22</mn><mo>+</mo></mrow></msup></math></span>, and Sm<span><math><msup><mrow></mrow><mrow><mn>24</mn><mo>+</mo></mrow></msup></math></span> ions in the wavelength range of 200–600 nm were measured using an electron beam ion trap. A total of thirty four magnetic dipole transition lines were identified with twenty four lines newly assigned. Theoretical calculations were performed using the multi-configuration Dirac–Hartree–Fock and relativistic configuration interaction methods, incorporating the Breit interaction and the dominant quantum electrodynamics effects. The calculated results show good agreement with experiment, with an average deviation below 1.0%. The experimental spectra reported provide reliable reference data for further studies.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109795"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-17DOI: 10.1016/j.jqsrt.2025.109794
Sergey A. Astashkevich
A model of a spatially homogenous stationary Cs-containing photoplasma far from optical saturation is developed for uniform spectral pumping within the D1 and D2 cesium line range. The plasma chemistry, radiation transfer, and ambipolar diffusion of charged particles are all explicitly considered. Unlike previous studies of sodium-containing photoplasmas, this work includes associative ionization at both resonance and non-resonance levels. Along with the penning and associative ionization processes, the first and second kind of electron collisions and stepwise ionization were considered. Radiation transfer is accounted for the Voigt profile for the resonance cesium lines in the Biberman-Holstein approximation, taking into account self-broadening and Van der Waals broadening of the lines by the buffer gas atoms. The electron density and temperature and densities of atomic and diatomic cesium ions were determined by solving a system of equations for the atomic level and ion densities as well as the electron energy balance. For example, parameters for pure Cs and Cs–Ar photoplasmas in a cylindrical cell were obtained over a wide range of resonance excitation rates and partial pressures of gas components. A comparison with previously obtained data for cesium and sodium photoplasmas was made. The results can be used to design photoelectric converters based on cesium-containing gas cells.
{"title":"Model study of stationary quasi-homogeneous cesium-containing photoplasma","authors":"Sergey A. Astashkevich","doi":"10.1016/j.jqsrt.2025.109794","DOIUrl":"10.1016/j.jqsrt.2025.109794","url":null,"abstract":"<div><div>A model of a spatially homogenous stationary Cs-containing photoplasma far from optical saturation is developed for uniform spectral pumping within the D1 and D2 cesium line range. The plasma chemistry, radiation transfer, and ambipolar diffusion of charged particles are all explicitly considered. Unlike previous studies of sodium-containing photoplasmas, this work includes associative ionization at both resonance and non-resonance levels. Along with the penning and associative ionization processes, the first and second kind of electron collisions and stepwise ionization were considered. Radiation transfer is accounted for the Voigt profile for the resonance cesium lines in the Biberman-Holstein approximation, taking into account self-broadening and Van der Waals broadening of the lines by the buffer gas atoms. The electron density and temperature and densities of atomic and diatomic cesium ions were determined by solving a system of equations for the atomic level and ion densities as well as the electron energy balance. For example, parameters for pure Cs and Cs–Ar photoplasmas in a cylindrical cell were obtained over a wide range of resonance excitation rates and partial pressures of gas components. A comparison with previously obtained data for cesium and sodium photoplasmas was made. The results can be used to design photoelectric converters based on cesium-containing gas cells.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109794"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-11-12DOI: 10.1016/j.jqsrt.2025.109741
Steven Lanier
Simulating light interaction with complex arbitrary geometry is crucial across the sciences. The Discrete Dipole Approximation (DDA) offers versatility for such problems but faces significant computational challenges, particularly for optically large or high-index systems, limiting its practical scope. Prior circulant preconditioning work, building on frameworks by Chan and Olkin and applied to DDA by Groth et al., demonstrated speedups primarily for quasi-2D geometries while attempts to create stable three-level preconditioners for general 3D structures were unsuccessful. Here we present an efficient and robust DDA implementation featuring a successful three-level circulant preconditioner stabilized through several key enhancements: optimized complex diagonal elements, controlled dimensional expansion and folding of the preconditioner structure, and automated parameter tuning via reinforcement learning. This preconditioning strategy is integrated with a custom GPU iterative solver incorporating stability improvements. Our approach effectively handles arbitrary 3D geometries, including non-homogeneous objects with varying refractive indices and multi-object scenarios with differing material values. The implementation yields substantial computational gains, often exceeding an order of magnitude reduction in iteration count or solution time, enabling convergence for more traditionally difficult problems and reducing demanding simulations from hours to minutes or even seconds on standard hardware. This work significantly extends the range of complex systems amenable to DDA modeling, facilitating advanced electromagnetic simulations relevant to nanophotonics, materials characterization, and atmospheric/biological optics.
{"title":"Learning to precondition: Reinforcement learning enhanced three-level circulant preconditioning for the Discrete Dipole Approximation","authors":"Steven Lanier","doi":"10.1016/j.jqsrt.2025.109741","DOIUrl":"10.1016/j.jqsrt.2025.109741","url":null,"abstract":"<div><div>Simulating light interaction with complex arbitrary geometry is crucial across the sciences. The Discrete Dipole Approximation (DDA) offers versatility for such problems but faces significant computational challenges, particularly for optically large or high-index systems, limiting its practical scope. Prior circulant preconditioning work, building on frameworks by Chan and Olkin and applied to DDA by Groth et al., demonstrated speedups primarily for quasi-2D geometries while attempts to create stable three-level preconditioners for general 3D structures were unsuccessful. Here we present an efficient and robust DDA implementation featuring a successful three-level circulant preconditioner stabilized through several key enhancements: optimized complex diagonal elements, controlled dimensional expansion and folding of the preconditioner structure, and automated parameter tuning via reinforcement learning. This preconditioning strategy is integrated with a custom GPU iterative solver incorporating stability improvements. Our approach effectively handles arbitrary 3D geometries, including non-homogeneous objects with varying refractive indices and multi-object scenarios with differing material values. The implementation yields substantial computational gains, often exceeding an order of magnitude reduction in iteration count or solution time, enabling convergence for more traditionally difficult problems and reducing demanding simulations from hours to minutes or even seconds on standard hardware. This work significantly extends the range of complex systems amenable to DDA modeling, facilitating advanced electromagnetic simulations relevant to nanophotonics, materials characterization, and atmospheric/biological optics.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109741"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-08DOI: 10.1016/j.jqsrt.2025.109789
Leonardo A. Ambrosio , Luiz F.M. Votto , Jianqi Shen , Gérard Gouesbet , Jiajie Wang
In light and acoustic scattering, physical fields such as acoustic pressure and electromagnetic waves are expanded in partial waves, the expansion coefficients being known as the beam shape coefficients (BSCs). In acoustics, the BSCs are found from scalar fields, while in optics transverse magnetic and electric BSCs are calculated from the radial electric and magnetic field components, respectively. The relationship between acoustic and electromagnetic BSCs has been a recent active area of research. Previous works have focused on the assumption that such a relationship can be established by forcing the acoustic/scalar fields to be particular components of electromagnetic vector potentials. Here, we present an alternative approach in which the scalar fields are directly associated with a transverse electric field component. Such an analysis extends previous work and allows for a direct description of the electromagnetic BSCs of important optical fields from scalar waves. The analysis is restricted to solutions to the scalar Helmholtz equation which carry a propagating factor of the form , such a factor being the only one to carry any dependence on the axial coordinate. An example is provided for a specific class of structured, non-diffracting fields constructed from discrete superpositions of Bessel beams, known in the literature as frozen waves.
{"title":"Relationship between scalar and electromagnetic beam shape coefficients for fields with a propagating factor of exp(±iβz): Linear and circular polarizations","authors":"Leonardo A. Ambrosio , Luiz F.M. Votto , Jianqi Shen , Gérard Gouesbet , Jiajie Wang","doi":"10.1016/j.jqsrt.2025.109789","DOIUrl":"10.1016/j.jqsrt.2025.109789","url":null,"abstract":"<div><div>In light and acoustic scattering, physical fields such as acoustic pressure and electromagnetic waves are expanded in partial waves, the expansion coefficients being known as the beam shape coefficients (BSCs). In acoustics, the BSCs are found from scalar fields, while in optics transverse magnetic and electric BSCs are calculated from the radial electric and magnetic field components, respectively. The relationship between acoustic and electromagnetic BSCs has been a recent active area of research. Previous works have focused on the assumption that such a relationship can be established by forcing the acoustic/scalar fields to be particular components of electromagnetic vector potentials. Here, we present an alternative approach in which the scalar fields are directly associated with a transverse electric field component. Such an analysis extends previous work and allows for a direct description of the electromagnetic BSCs of important optical fields from scalar waves. The analysis is restricted to solutions to the scalar Helmholtz equation which carry a propagating factor of the form <span><math><mrow><mo>exp</mo><mrow><mo>(</mo><mo>±</mo><mi>i</mi><mi>β</mi><mi>z</mi><mo>)</mo></mrow></mrow></math></span>, such a factor being the only one to carry any dependence on the axial coordinate. An example is provided for a specific class of structured, non-diffracting fields constructed from discrete superpositions of Bessel beams, known in the literature as <em>frozen waves</em>.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109789"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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