Pub 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":"2025-12-11","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 : 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":"2025-12-08","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}
Pub Date : 2025-12-08DOI: 10.1016/j.jqsrt.2025.109785
Héctor Antonio Solano Lamphar
Artificial Light at Night (ALAN) poses significant public health challenges by disrupting circadian rhythms and increasing melatonin suppression. This study introduces a dynamic modeling framework employing synthetic population simulations to quantify the health impacts of ALAN under varying exposure scenarios. The model integrates spatial, temporal, behavioral, and policy dimensions, enabling the evaluation of interventions such as warm LED lighting (, ), lighting ordinances, and community-wide curfews. Simulations demonstrate that these interventions can reduce melatonin suppression by up to 25% in high-risk zones. Clustering analysis identifies high-suppression areas, providing critical insights for urban planning and policymaking. Sensitivity analyses highlight the pivotal role of policy compliance and behavioral adaptations in mitigating ALAN’s health impacts. Using synthetic populations ensures ethical compliance by avoiding real human data, while the model’s scalability supports application across diverse urban contexts. Future work will integrate ground based illuminance measurements to enhance predictive accuracy and support equitable strategies for mitigating ALAN’s health impacts.
{"title":"Modeling the health impacts of urban light pollution: Synthetic populations and behavioral interventions","authors":"Héctor Antonio Solano Lamphar","doi":"10.1016/j.jqsrt.2025.109785","DOIUrl":"10.1016/j.jqsrt.2025.109785","url":null,"abstract":"<div><div>Artificial Light at Night (ALAN) poses significant public health challenges by disrupting circadian rhythms and increasing melatonin suppression. This study introduces a dynamic modeling framework employing synthetic population simulations to quantify the health impacts of ALAN under varying exposure scenarios. The model integrates spatial, temporal, behavioral, and policy dimensions, enabling the evaluation of interventions such as warm LED lighting (<span><math><mrow><mo>≤</mo><mn>3000</mn><mspace></mspace><mtext>K</mtext></mrow></math></span>, <span><math><mrow><mo>≤</mo><mn>10</mn><mtext>%</mtext><mo>,</mo><mtext>emission at 450–490 nm</mtext></mrow></math></span>), lighting ordinances, and community-wide curfews. Simulations demonstrate that these interventions can reduce melatonin suppression by up to 25% in high-risk zones. Clustering analysis identifies high-suppression areas, providing critical insights for urban planning and policymaking. Sensitivity analyses highlight the pivotal role of policy compliance and behavioral adaptations in mitigating ALAN’s health impacts. Using synthetic populations ensures ethical compliance by avoiding real human data, while the model’s scalability supports application across diverse urban contexts. Future work will integrate ground based illuminance measurements to enhance predictive accuracy and support equitable strategies for mitigating ALAN’s health impacts.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109785"},"PeriodicalIF":1.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704977","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 : 2025-12-06DOI: 10.1016/j.jqsrt.2025.109786
Jiayi Zhang , Tan Qu , Yan Zhang , Jiaji Wu , Zhensen Wu
Predicting the complex spectral responses of metasurfaces is critical for their design, whereas conventional simulations are computationally expensive, and existing neural models often lack generalization and fail to maintain phase–amplitude consistency. Thus, a unified complex residual neural network (Uni-CRN) for forward modeling of diverse all-dielectric metasurfaces, including cylindrical and H-shaped structures is proposed in this paper. Uni-CRN integrates complex-valued operators with residual modules in a three-stage architecture—comprising input projection, stacked complex residual blocks, and output prediction—enabling direct learning in the complex domain while preserving gradient stability in deep networks. This unified framework allows the same model to handle multiple metasurface types with minimal modification. Experiments demonstrate that Uni-CRN achieves a composite mean squared error of 3.2 × 10⁻⁴, with amplitude and phase prediction fidelities of 95.50 % and 99.37 % on the cylindrical dataset, outperforming previous methods. The results highlight Uni-CRN as an efficient and general approach for metasurface spectral modeling, providing a robust foundation for inverse design and cross-structure transfer learning.
{"title":"A unified complex residual network for spectrum prediction of full-dielectric metasurfaces","authors":"Jiayi Zhang , Tan Qu , Yan Zhang , Jiaji Wu , Zhensen Wu","doi":"10.1016/j.jqsrt.2025.109786","DOIUrl":"10.1016/j.jqsrt.2025.109786","url":null,"abstract":"<div><div>Predicting the complex spectral responses of metasurfaces is critical for their design, whereas conventional simulations are computationally expensive, and existing neural models often lack generalization and fail to maintain phase–amplitude consistency. Thus, a unified complex residual neural network (Uni-CRN) for forward modeling of diverse all-dielectric metasurfaces, including cylindrical and H-shaped structures is proposed in this paper. Uni-CRN integrates complex-valued operators with residual modules in a three-stage architecture—comprising input projection, stacked complex residual blocks, and output prediction—enabling direct learning in the complex domain while preserving gradient stability in deep networks. This unified framework allows the same model to handle multiple metasurface types with minimal modification. Experiments demonstrate that Uni-CRN achieves a composite mean squared error of 3.2 × 10⁻⁴, with amplitude and phase prediction fidelities of 95.50 % and 99.37 % on the cylindrical dataset, outperforming previous methods. The results highlight Uni-CRN as an efficient and general approach for metasurface spectral modeling, providing a robust foundation for inverse design and cross-structure transfer learning.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109786"},"PeriodicalIF":1.9,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689298","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}
Spectra of HF mixtures with helium were recorded at elevated pressures ranging from 1 to 11 atm at 297.8(2) K. The rovibrational lines in the first overtone band were fitted with Voigt and Rautian profiles. The broadening and shifting coefficients for 19 lines in the first overtone are reported. An estimate for the velocity changing shifting coefficients for 11 lines is obtained. To the best of our knowledge, most of the reported line parameters are novel. Herman–Wallis coefficients were determined from the line intensity distribution as well.
{"title":"Helium-induced broadening and shifting in the first overtone of hydrogen fluoride","authors":"I.A. Tolstikov , A.V. Domanskaya , O.O. Diachkova , R.E. Asfin","doi":"10.1016/j.jqsrt.2025.109787","DOIUrl":"10.1016/j.jqsrt.2025.109787","url":null,"abstract":"<div><div>Spectra of HF mixtures with helium were recorded at elevated pressures ranging from 1 to 11 atm at 297.8(2) K. The rovibrational lines in the first overtone band were fitted with Voigt and Rautian profiles. The broadening and shifting coefficients for 19 lines in the first overtone are reported. An estimate for the velocity changing shifting coefficients for 11 lines is obtained. To the best of our knowledge, most of the reported line parameters are novel. Herman–Wallis coefficients were determined from the line intensity distribution as well.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109787"},"PeriodicalIF":1.9,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689299","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 : 2025-12-04DOI: 10.1016/j.jqsrt.2025.109784
Haojiang Chen , Qingzhi Lai , Min Wang , Yinmo Xie , Lanxin Ma , Jianyu Tan
Random waves on the surface of oil spills on the sea occur due to various factors, including sea breezes, which have a notable influence on the radiative characteristics of the oil spills. Accurately determining the effect of complex sea states on the radiative characteristics of oil spills is crucial for enhancing the accuracy of oil-spill monitoring. This study proposes a modified wave spectrum model incorporating Marangoni effect corrections to model rough oil-spill surfaces in complex sea states. Based on this, a radiative transfer model using the Monte Carlo method was developed to investigate the radiative characteristics of oil-spill and oil-free surfaces under varying wind speeds. The findings demonstrate that the surface roughness of oil spills is significantly lower than that of oil-free surfaces at identical wind speeds. This phenomenon is attributed to the higher viscosity of crude oil compared with that of seawater. Such disparities in the surface roughness leads to distinct variations in the spectral characteristics of reflectance. Neglecting these differences may result in inaccurate results. When employing the ELFOUHAILY wave spectrum model at a wind speed of 3 m/s, the mean relative error in reflectance was recorded as 1.15 %. This error increased with wind speed; at 15 m/s, the error increased to 8.2 %. As the wavelength increased, the reflectance of the oil spills decreased. Significant reflectance peaks were observed at 1760 nm and 1920 nm range. An oil-seawater contrast analysis, coupled with an evaluation of the effects of atmospheric absorption bands, indicated that the 1760 nm band was the most effective for detecting oil spills.
{"title":"Investigation of the radiative characteristics of an oil-covered rough sea surface using a modified wave spectrum model","authors":"Haojiang Chen , Qingzhi Lai , Min Wang , Yinmo Xie , Lanxin Ma , Jianyu Tan","doi":"10.1016/j.jqsrt.2025.109784","DOIUrl":"10.1016/j.jqsrt.2025.109784","url":null,"abstract":"<div><div>Random waves on the surface of oil spills on the sea occur due to various factors, including sea breezes, which have a notable influence on the radiative characteristics of the oil spills. Accurately determining the effect of complex sea states on the radiative characteristics of oil spills is crucial for enhancing the accuracy of oil-spill monitoring. This study proposes a modified wave spectrum model incorporating Marangoni effect corrections to model rough oil-spill surfaces in complex sea states. Based on this, a radiative transfer model using the Monte Carlo method was developed to investigate the radiative characteristics of oil-spill and oil-free surfaces under varying wind speeds. The findings demonstrate that the surface roughness of oil spills is significantly lower than that of oil-free surfaces at identical wind speeds. This phenomenon is attributed to the higher viscosity of crude oil compared with that of seawater. Such disparities in the surface roughness leads to distinct variations in the spectral characteristics of reflectance. Neglecting these differences may result in inaccurate results. When employing the ELFOUHAILY wave spectrum model at a wind speed of 3 m/s, the mean relative error in reflectance was recorded as 1.15 %. This error increased with wind speed; at 15 m/s, the error increased to 8.2 %. As the wavelength increased, the reflectance of the oil spills decreased. Significant reflectance peaks were observed at 1760 nm and 1920 nm range. An oil-seawater contrast analysis, coupled with an evaluation of the effects of atmospheric absorption bands, indicated that the 1760 nm band was the most effective for detecting oil spills.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109784"},"PeriodicalIF":1.9,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689310","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}
A multiscale modeling approach is proposed to determine the normal spectral emissivity of a 1.92 mm thick and 98% dense cerium oxide ceramic containing a small amount of micron size pores. The model is based on measurements of the electrical conductivity of the ceramic for the thermal operating regime set by the actual solar thermochemical production of H, i.e. from 900 to 1500 °C at a oxygen partial pressure of 10−5 atm. From a radiative point of view, the ceramic is defined as the volumetric distribution of spherical pores in a set of grains forming a radiatively homogeneous and continuous matrix. Room temperature normal hemispherical reflectance and transmittance measurements give analytically the scattering coefficient of this absorbing and scattering medium, considered independent from the temperature, using the modified two-flux approximation. The absorption coefficient is given at a fixed temperature and atmosphere by a semi-quantum Drude-Lorentz model whose parameters are derived from electrical conductivity measurements. The combination of both coefficients allow to determine critical optical thickness of the sample depending on the temperature, and to model emissivity. The multiscale model predicts the increase of an emissivity plateau between 2500 and 20000 cm−1 with the temperature, going from 0.70 at 900 °C to 0.84 at 1500 °C, higher than the value of 0.20 measured at room temperature.
{"title":"Multiscale modeling of the high-temperature radiative properties of ceria ceramics under thermochemical redox conditions","authors":"Léo Gaillard , Pierre-Marie Geffroy , Abderezak Aouali , Benoit Rousseau","doi":"10.1016/j.jqsrt.2025.109783","DOIUrl":"10.1016/j.jqsrt.2025.109783","url":null,"abstract":"<div><div>A multiscale modeling approach is proposed to determine the normal spectral emissivity of a 1.92 mm thick and 98% dense cerium oxide ceramic containing a small amount of micron size pores. The model is based on measurements of the electrical conductivity of the ceramic for the thermal operating regime set by the actual solar thermochemical production of H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, i.e. from 900 to 1500 °C at a oxygen partial pressure of 10<sup>−5</sup> atm. From a radiative point of view, the ceramic is defined as the volumetric distribution of spherical pores in a set of grains forming a radiatively homogeneous and continuous matrix. Room temperature normal hemispherical reflectance and transmittance measurements give analytically the scattering coefficient of this absorbing and scattering medium, considered independent from the temperature, using the modified two-flux approximation. The absorption coefficient is given at a fixed temperature and atmosphere by a semi-quantum Drude-Lorentz model whose parameters are derived from electrical conductivity measurements. The combination of both coefficients allow to determine critical optical thickness of the sample depending on the temperature, and to model emissivity. The multiscale model predicts the increase of an emissivity plateau between 2500 and 20000 cm<sup>−1</sup> with the temperature, going from 0.70 at 900 °C to 0.84 at 1500 °C, higher than the value of 0.20 measured at room temperature.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109783"},"PeriodicalIF":1.9,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689301","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 : 2025-12-02DOI: 10.1016/j.jqsrt.2025.109781
Ivan V. Tarabukin , Denis G. Poydashev , Leonid A. Surin
The hyperfine structure of the (para)-NH3–(ortho)-H2 van der Waals molecular complex has been observed and analyzed for the first time. The measurements of the pure rotational transitions were carried out in the frequency range of 75-190 GHz using a newly developed millimeter-wave jet spectrometer with a molecular beam aligned coaxially with the direction of millimeter-waves propagation. 14N nuclear quadrupole coupling constant of NH3, spin-spin and spin-rotation interaction constants of the two protons of the H2 molecule were determined for (para)-NH3–(ortho)-H2 in its ground Π state. The obtained parameters contain useful information about angular orientation of the NH3 and H2 monomers within the van der Waals complex and provide an additional tool for evaluating the quality of the NH3–H2 interaction potential. The latter determines the reliability of the calculated excitation and de-excitation rates of ammonia during collisions with hydrogen in the dense interstellar clouds.
{"title":"Rotational spectrum and hyperfine structure of the (para)-NH3–(ortho)-H2 van der Waals molecular complex","authors":"Ivan V. Tarabukin , Denis G. Poydashev , Leonid A. Surin","doi":"10.1016/j.jqsrt.2025.109781","DOIUrl":"10.1016/j.jqsrt.2025.109781","url":null,"abstract":"<div><div>The hyperfine structure of the (<em>para</em>)-NH<sub>3</sub>–(<em>ortho</em>)-H<sub>2</sub> van der Waals molecular complex has been observed and analyzed for the first time. The measurements of the pure rotational transitions were carried out in the frequency range of 75-190 GHz using a newly developed millimeter-wave jet spectrometer with a molecular beam aligned coaxially with the direction of millimeter-waves propagation. <sup>14</sup>N nuclear quadrupole coupling constant of NH<sub>3</sub>, spin-spin and spin-rotation interaction constants of the two protons of the H<sub>2</sub> molecule were determined for (<em>para</em>)-NH<sub>3</sub>–(<em>ortho</em>)-H<sub>2</sub> in its ground Π state. The obtained parameters contain useful information about angular orientation of the NH<sub>3</sub> and H<sub>2</sub> monomers within the van der Waals complex and provide an additional tool for evaluating the quality of the NH<sub>3</sub>–H<sub>2</sub> interaction potential. The latter determines the reliability of the calculated excitation and de-excitation rates of ammonia during collisions with hydrogen in the dense interstellar clouds.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109781"},"PeriodicalIF":1.9,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145657483","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 : 2025-12-02DOI: 10.1016/j.jqsrt.2025.109782
Saleh O. Allehabi , V.A. Dzuba , V.V. Flambaum
We use advanced computational techniques to study the electronic structure of the Hf ion, with the goal of assessing its potential for use in highly accurate atomic optical clocks and in the search for new physics. Such clocks should combine low sensitivity to external perturbations with high sensitivity to a possible time variation of the fine-structure constant . The system features two clock transitions. One is an transition in terms of single-electron states, which exhibits strong sensitivity to variations in . The other is an electric-quadrupole (E2) transition between states of the ground-state configuration, which can serve as an anchor transition for measuring one frequency against the other.
All three relevant states possess very small and nearly equal static dipole polarizabilities, resulting in an extremely small blackbody-radiation shift. The quadrupole shift is also small and can be further suppressed. Altogether, Hf appears to be a highly promising candidate for both precision timekeeping and searches for new physics.
{"title":"Hf12+ ion: Highly charged ion for next-generation atomic clocks and tests of fundamental physics","authors":"Saleh O. Allehabi , V.A. Dzuba , V.V. Flambaum","doi":"10.1016/j.jqsrt.2025.109782","DOIUrl":"10.1016/j.jqsrt.2025.109782","url":null,"abstract":"<div><div>We use advanced computational techniques to study the electronic structure of the Hf<span><math><msup><mrow></mrow><mrow><mn>12</mn><mo>+</mo></mrow></msup></math></span> ion, with the goal of assessing its potential for use in highly accurate atomic optical clocks and in the search for new physics. Such clocks should combine low sensitivity to external perturbations with high sensitivity to a possible time variation of the fine-structure constant <span><math><mi>α</mi></math></span>. The system features two clock transitions. One is an <span><math><mrow><mi>f</mi><mo>−</mo><mi>p</mi></mrow></math></span> transition in terms of single-electron states, which exhibits strong sensitivity to variations in <span><math><mi>α</mi></math></span>. The other is an electric-quadrupole (E2) transition between states of the ground-state configuration, which can serve as an anchor transition for measuring one frequency against the other.</div><div>All three relevant states possess very small and nearly equal static dipole polarizabilities, resulting in an extremely small blackbody-radiation shift. The quadrupole shift is also small and can be further suppressed. Altogether, Hf<span><math><msup><mrow></mrow><mrow><mn>12</mn><mo>+</mo></mrow></msup></math></span> appears to be a highly promising candidate for both precision timekeeping and searches for new physics.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"351 ","pages":"Article 109782"},"PeriodicalIF":1.9,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145657496","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 : 2025-11-29DOI: 10.1016/j.jqsrt.2025.109778
Rolf Buhler, Philippe Deverchère, Christophe Plotard, Sébastien Vauclair
Artificial Light At Night (ALAN) has been increasing steadily over the past century, particularly during the last decade. This leads to rising light pollution, which is known to have adverse effects on living organisms, including humans. We present a new software package to model light pollution from ground radiance measurements. The software is called Otus 3 and incorporates innovative ALAN diffusion models with different atmospheric profiles, cloud covers and urban emission functions. To date, light pollution modelling typically focused on calculating the zenith luminance of the skyglow produced by city lights. In Otus 3 we extend this and additionally model the horizontal illuminance on the ground, including the contributions from skyglow and the direct illumination. We applied Otus 3 to France using ground radiance data from the Visible Infrared Imaging Radiometer Suite (VIIRS). We calibrated our models using precise sky brightness measurements we obtained over 6 years at 139 different locations and make this dataset publicly available. We produced the first artificial illuminance map for France for the periods of 2013–2018 and 2019–2024. We found that the artificial ground illuminance in the middle of the night decreased by 23% between these two periods, in stark contrast to the global trend.
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