This paper presents the far-infrared collision-induced absorption (CIA) spectra for CH CO pairs obtained using trajectory-based simulations across a broad temperature range of 70–400 K. Our calculations rely on explicit quantum-chemical calculation of the potential energy and induced dipole surfaces, constructed under the rigid-monomer approximation. Our developed trajectory-based method enables modeling of the true dimer contribution to CIA profile, which is particularly important at low temperatures. Furthermore, we introduce a significant improvement to the Monte Carlo computational scheme, which substantially accelerates its convergence in the frame of our method. The spectra obtained in this work thus provide a reliable reference for evaluating the impact of CIA in radiative transfer models, with direct application for CO–rich atmospheres such as Martian paleoatmosphere.
{"title":"Trajectory-based far infrared collision-induced absorption spectra of CH4 CO2 in the temperature range from 70 K to 400 K","authors":"A.A. Finenko , D.N. Chistikov , A.O. Koroleva , A.A. Vigasin","doi":"10.1016/j.jqsrt.2026.109810","DOIUrl":"10.1016/j.jqsrt.2026.109810","url":null,"abstract":"<div><div>This paper presents the far-infrared collision-induced absorption (CIA) spectra for CH<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> <img>CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> pairs obtained using trajectory-based simulations across a broad temperature range of 70–400 K. Our calculations rely on explicit quantum-chemical calculation of the potential energy and induced dipole surfaces, constructed under the rigid-monomer approximation. Our developed trajectory-based method enables modeling of the true dimer contribution to CIA profile, which is particularly important at low temperatures. Furthermore, we introduce a significant improvement to the Monte Carlo computational scheme, which substantially accelerates its convergence in the frame of our method. The spectra obtained in this work thus provide a reliable reference for evaluating the impact of CIA in radiative transfer models, with direct application for CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>–rich atmospheres such as Martian paleoatmosphere.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"352 ","pages":"Article 109810"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956750","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: 2025-11-19DOI: 10.1016/j.jqsrt.2025.109759
E.S. Medvedev, V.G. Ushakov
The ability of our semi-empirical irregular dipole-moment functions (2022) and (2025) to predict the intensities of the yet unobserved lines, as well as to describe the observed ones not used in the fitting, is demonstrated by comparison with recent measurements in the 0-0, 1-0, 3-0, and 7-0 bands.
{"title":"The predictive power of the calculated line lists of carbon monoxide","authors":"E.S. Medvedev, V.G. Ushakov","doi":"10.1016/j.jqsrt.2025.109759","DOIUrl":"10.1016/j.jqsrt.2025.109759","url":null,"abstract":"<div><div>The ability of our semi-empirical irregular dipole-moment functions (2022) and (2025) to predict the intensities of the yet unobserved lines, as well as to describe the observed ones not used in the fitting, is demonstrated by comparison with recent measurements in the 0-0, 1-0, 3-0, and 7-0 bands.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109759"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553985","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: 2025-11-13DOI: 10.1016/j.jqsrt.2025.109737
K. Leroux, A. Rizopoulos, J. Vander Auwera
Allene (propadiene) and isoprene (2-methyl-1,3-butadiene) are two volatile unsaturated hydrocarbons that play a key role in the chemistry of the Earth and planetary atmospheres. Optical remote sensing of these compounds in these environments require that appropriate quantitative spectroscopic information be available. This information is however limited for these species. In particular, wavenumber dependent absorption cross sections have only been reported once in the thermal infrared, relevant for current and future space missions. In the present work, Fourier transform spectra of allene and isoprene mixed with nitrogen at a total pressure of 1 atm have been recorded at 296 K and a resolution of 0.03 cm−1 in the ranges cm−1 ( ) and cm−1 ( ), respectively. Absorption cross sections have been derived from 5 to 8 allene or isoprene sample pressures using a linear regression method and their overall uncertainties estimated. Obtained by direct summation over the whole ranges studied for each species, their integrated values were found to be and cm/molecule for allene and isoprene, respectively. These absorption cross sections and integrated values were compared with previous measurements reported in the literature.
{"title":"Mid-infrared absorption cross sections for two unsaturated hydrocarbons: Allene and isoprene","authors":"K. Leroux, A. Rizopoulos, J. Vander Auwera","doi":"10.1016/j.jqsrt.2025.109737","DOIUrl":"10.1016/j.jqsrt.2025.109737","url":null,"abstract":"<div><div>Allene (propadiene) and isoprene (2-methyl-1,3-butadiene) are two volatile unsaturated hydrocarbons that play a key role in the chemistry of the Earth and planetary atmospheres. Optical remote sensing of these compounds in these environments require that appropriate quantitative spectroscopic information be available. This information is however limited for these species. In particular, wavenumber dependent absorption cross sections have only been reported once in the thermal infrared, relevant for current and future space missions. In the present work, Fourier transform spectra of allene and isoprene mixed with nitrogen at a total pressure of 1 atm have been recorded at 296 K and a resolution of 0.03 cm<sup>−1</sup> in the ranges <span><math><mrow><mn>600</mn><mo>−</mo><mn>2100</mn></mrow></math></span> cm<sup>−1</sup> (<span><math><mrow><mn>4</mn><mo>.</mo><mn>76</mn><mo>−</mo><mn>16</mn><mo>.</mo><mn>7</mn></mrow></math></span> <span><math><mrow><mi>μ</mi><mi>m</mi></mrow></math></span>) and <span><math><mrow><mn>600</mn><mo>−</mo><mn>2000</mn></mrow></math></span> cm<sup>−1</sup> (<span><math><mrow><mn>5</mn><mo>.</mo><mn>0</mn><mo>−</mo><mn>16</mn><mo>.</mo><mn>7</mn></mrow></math></span> <span><math><mrow><mi>μ</mi><mi>m</mi></mrow></math></span>), respectively. Absorption cross sections have been derived from 5 to 8 allene or isoprene sample pressures using a linear regression method and their overall uncertainties estimated. Obtained by direct summation over the whole ranges studied for each species, their integrated values were found to be <span><math><mrow><mn>2</mn><mo>.</mo><mn>88</mn><mspace></mspace><mrow><mo>(</mo><mn>7</mn><mo>)</mo></mrow></mrow></math></span> and <span><math><mrow><mn>2</mn><mo>.</mo><mn>64</mn><mspace></mspace><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>17</mn></mrow></msup></mrow></math></span> cm/molecule for allene and isoprene, respectively. These absorption cross sections and integrated values were compared with previous measurements reported in the literature.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109737"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531875","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: 2026-01-07DOI: 10.1016/j.jqsrt.2026.109809
Akhlesh Lakhtakia
Quantifying the dissimilarity in the locations of two plane waves on the Poincaré sphere by using spinor algebra, the concept of geometric phase was applied to initiate a novel portrayal of electromagnetic scattering by a three-dimensional object in free space. Whereas the incident electromagnetic field is that of an arbitrarily polarized plane wave, the direction-dependent far-zone scattering amplitude was used to define direction-dependent Stokes parameters for the scattered field. Both symmetric and asymmetric Poincaré spinors were formulated to characterize the polarization states of incident plane wave and the far-zone scattering amplitude, and two different geometric phases were defined therefrom. Density plots of both geometric phases were calculated for six different homogeneous isotropic spheres with different linear constitutive properties and boundary conditions: dielectric–magnetic spheres (non-dissipative and dissipative), impedance spheres, perfect electrically conducting spheres, charged dielectric–magnetic spheres, dielectric–magnetic spheres with topologically insulating surface states, isotropic chiral spheres, and isotropic chiral spheres with topologically insulating surface states. The incident plane waves were taken to be linearly and circularly polarized, for the sake of illustration. Numerical results revealed that geometric-phase density plots possess significantly richer features than their counterparts for the differential scattering efficiency. The geometric-phase portrayals exhibit enhanced sensitivity to changes in the size and composition of the scatterer, the boundary conditions, and the incident polarization state, suggesting promise for inverse-scattering problems.
{"title":"van de Hulst essay: Geometric-phase portrayal of electromagnetic scattering by a three-dimensional object in free space","authors":"Akhlesh Lakhtakia","doi":"10.1016/j.jqsrt.2026.109809","DOIUrl":"10.1016/j.jqsrt.2026.109809","url":null,"abstract":"<div><div>Quantifying the dissimilarity in the locations of two plane waves on the Poincaré sphere by using spinor algebra, the concept of geometric phase was applied to initiate a novel portrayal of electromagnetic scattering by a three-dimensional object in free space. Whereas the incident electromagnetic field is that of an arbitrarily polarized plane wave, the direction-dependent far-zone scattering amplitude was used to define direction-dependent Stokes parameters for the scattered field. Both symmetric and asymmetric Poincaré spinors were formulated to characterize the polarization states of incident plane wave and the far-zone scattering amplitude, and two different geometric phases were defined therefrom. Density plots of both geometric phases were calculated for six different homogeneous isotropic spheres with different linear constitutive properties and boundary conditions: dielectric–magnetic spheres (non-dissipative and dissipative), impedance spheres, perfect electrically conducting spheres, charged dielectric–magnetic spheres, dielectric–magnetic spheres with topologically insulating surface states, isotropic chiral spheres, and isotropic chiral spheres with topologically insulating surface states. The incident plane waves were taken to be linearly and circularly polarized, for the sake of illustration. Numerical results revealed that geometric-phase density plots possess significantly richer features than their counterparts for the differential scattering efficiency. The geometric-phase portrayals exhibit enhanced sensitivity to changes in the size and composition of the scatterer, the boundary conditions, and the incident polarization state, suggesting promise for inverse-scattering problems.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"352 ","pages":"Article 109809"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928117","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: 2026-01-09DOI: 10.1016/j.jqsrt.2026.109821
Aravintha Raj Ravichandran, Vanessa Bristow, Joohyun Seo, Richard Z. Zhang
Spectrometry of lunar dust simulants can provide better understanding of the Moon’s surface albedo, thermal radiation to its environment, detection of composition variations, and identifying presence of water. The Moon’s soil or regolith is composed of fine dust particles of mostly silica, alumina, and lime, with variations between lighter Highlands (Artemis) regions and darker Mares (Apollo) valleys. To better understand the variations on optical properties, we perform broadband diffuse and specular spectrometry from visible to far-infrared wavelengths of four Lunar regolith simulants. Dust simulants of coarse and fine blends were imaged in scanning electron microscope to validate the particle size distributions. In the visible to near-IR, fine-particle simulants show fewer differences in solar absorption and albedo, while FTIR measurements show compositional oxide differences. Surface absorptivity can vary between 0.63 at the Highlands and 0.79 in Mares, while Lunar albedo obtained from specular spectrometry relative to a Lambertian white reflecting standard can range between 0.79 and 0.64, respectively. Using diffuse FTIR spectrometry, thermal emissivity relative to room temperature blackbody across all Lunar simulants are around 0.78. Variations in spectral reflectance and emittance are dependent on sample humidity and heat treatments, aggregate packing, and scattering from large particles. This work can improve optical sensing methods, dust processing, and in situ resource manufacturing of Lunar regolith.
{"title":"Broadband spectrometry and thermal radiative properties of lunar dust simulants","authors":"Aravintha Raj Ravichandran, Vanessa Bristow, Joohyun Seo, Richard Z. Zhang","doi":"10.1016/j.jqsrt.2026.109821","DOIUrl":"10.1016/j.jqsrt.2026.109821","url":null,"abstract":"<div><div>Spectrometry of lunar dust simulants can provide better understanding of the Moon’s surface albedo, thermal radiation to its environment, detection of composition variations, and identifying presence of water. The Moon’s soil or regolith is composed of fine dust particles of mostly silica, alumina, and lime, with variations between lighter Highlands (Artemis) regions and darker Mares (Apollo) valleys. To better understand the variations on optical properties, we perform broadband diffuse and specular spectrometry from visible to far-infrared wavelengths of four Lunar regolith simulants. Dust simulants of coarse and fine blends were imaged in scanning electron microscope to validate the particle size distributions. In the visible to near-IR, fine-particle simulants show fewer differences in solar absorption and albedo, while FTIR measurements show compositional oxide differences. Surface absorptivity can vary between 0.63 at the Highlands and 0.79 in Mares, while Lunar albedo obtained from specular spectrometry relative to a Lambertian white reflecting standard can range between 0.79 and 0.64, respectively. Using diffuse FTIR spectrometry, thermal emissivity relative to room temperature blackbody across all Lunar simulants are around 0.78. Variations in spectral reflectance and emittance are dependent on sample humidity and heat treatments, aggregate packing, and scattering from large particles. This work can improve optical sensing methods, dust processing, and <em>in situ</em> resource manufacturing of Lunar regolith.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"352 ","pages":"Article 109821"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956751","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 method is proposed for calculating the diffuse component of the bidirectional reflectance distribution function (BRDF) of a medium with relatively strong absorption, such as seawater. Our approach is based on the expansion of the reflectance in orders of scattering through large angles (compared to the characteristic single-scattering angle), which leads to the reflectance expansion in inverse powers of the absorption coefficient. Explicit expressions for the first two terms of the expansion are derived. The first term reproduces the well-known result of quasi-single-scattering approximation, and the second one corresponds to the contribution of quasi-double scattering (the small-angle multiple scattering before, between, and after two events of large-angle scattering). To validate our analytical results, we carry out numerical integration of the radiative transfer equation for the Henyey–Greenstein (HG) phase function, as well as for the two-term HG and Morel et al (for Case I water) ones. For optical parameters typical to seawater, our analytical formula is in excellent agreement with the results of numerical radiative transfer calculations over a wide range of illumination/viewing angles. Remarkably, the relative contribution of the quasi-double scattering proves to be rather sensitive to the shape of the phase function in the backward hemisphere.
{"title":"Bidirectional reflectance of seawater","authors":"V.V. Marinyuk , M.A. Pavlova , D.B. Rogozkin , S.V. Sheberstov","doi":"10.1016/j.jqsrt.2026.109818","DOIUrl":"10.1016/j.jqsrt.2026.109818","url":null,"abstract":"<div><div>A method is proposed for calculating the diffuse component of the bidirectional reflectance distribution function (BRDF) of a medium with relatively strong absorption, such as seawater. Our approach is based on the expansion of the reflectance in orders of scattering through large angles (compared to the characteristic single-scattering angle), which leads to the reflectance expansion in inverse powers of the absorption coefficient. Explicit expressions for the first two terms of the expansion are derived. The first term reproduces the well-known result of quasi-single-scattering approximation, and the second one corresponds to the contribution of quasi-double scattering (the small-angle multiple scattering before, between, and after two events of large-angle scattering). To validate our analytical results, we carry out numerical integration of the radiative transfer equation for the Henyey–Greenstein (HG) phase function, as well as for the two-term HG and Morel et al (for Case I water) ones. For optical parameters typical to seawater, our analytical formula is in excellent agreement with the results of numerical radiative transfer calculations over a wide range of illumination/viewing angles. Remarkably, the relative contribution of the quasi-double scattering proves to be rather sensitive to the shape of the phase function in the backward hemisphere.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"352 ","pages":"Article 109818"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956753","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: 2025-12-06DOI: 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":"2026-03-01","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}
Using a homemade double-channel quantum cascade laser spectrometer operating in the mid-infrared, spectra of pure water vapour and water vapour diluted in argon were recorded in the 1300 cm-1 spectral region. A controlled atmosphere chamber was built around the spectrometer to reduce and stabilise ambient relative humidity, allowing the study of strongly absorbing H2O lines. Ten lines in the ν2 fundamental vibrational band of the water vapour main isotope, as well as two transitions in the 2ν2←ν2 hot band and three lines of the HDO and H218O isotopologues, were studied at room temperature. The experimental spectra were fitted with the Voigt, Rautian, speed-dependent Voigt, speed-dependent Rautian and Hartmann-Tran theoretical line-shape models. The broadening and shifting coefficients, along with their speed-dependencies, the collisional narrowing parameter, and, for some H2O-Ar lines, the parameter describing the correlation between velocity-changing and internal-state-changing collisions, were determined using a multi-spectrum fitting technique.
Results are compared to literature data when possible. For pure H2O spectroscopic parameters, the agreement with the literature reaches discrepancies over ± 10 %. For H2O-Ar collisional parameters, good agreement is found for the few available works in the literature. It is found that argon, as a noble gas, has weak collisional broadening and shifting effects on water vapour, but its relatively strong collisional narrowing makes for an interesting study of line-shape models. To our knowledge, this work is the first to report such advanced line-shape parameters of both studied molecular systems in this spectral region.
{"title":"Line-shape parameters of self- and Ar-perturbed water vapor lines in the ν2 band","authors":"Nicolas Dricot , Olivier Browet , Bastien Vispoel , Muriel Lepère","doi":"10.1016/j.jqsrt.2025.109748","DOIUrl":"10.1016/j.jqsrt.2025.109748","url":null,"abstract":"<div><div>Using a homemade double-channel quantum cascade laser spectrometer operating in the mid-infrared, spectra of pure water vapour and water vapour diluted in argon were recorded in the 1300 cm<sup>-1</sup> spectral region. A controlled atmosphere chamber was built around the spectrometer to reduce and stabilise ambient relative humidity, allowing the study of strongly absorbing H<sub>2</sub>O lines. Ten lines in the ν<sub>2</sub> fundamental vibrational band of the water vapour main isotope, as well as two transitions in the 2ν<sub>2</sub>←ν<sub>2</sub> hot band and three lines of the HDO and H<sub>2</sub><sup>18</sup>O isotopologues, were studied at room temperature. The experimental spectra were fitted with the Voigt, Rautian, speed-dependent Voigt, speed-dependent Rautian and Hartmann-Tran theoretical line-shape models. The broadening and shifting coefficients, along with their speed-dependencies, the collisional narrowing parameter, and, for some H<sub>2</sub>O-Ar lines, the parameter describing the correlation between velocity-changing and internal-state-changing collisions, were determined using a multi-spectrum fitting technique.</div><div>Results are compared to literature data when possible. For pure H<sub>2</sub>O spectroscopic parameters, the agreement with the literature reaches discrepancies over ± 10 %. For H<sub>2</sub>O-Ar collisional parameters, good agreement is found for the few available works in the literature. It is found that argon, as a noble gas, has weak collisional broadening and shifting effects on water vapour, but its relatively strong collisional narrowing makes for an interesting study of line-shape models. To our knowledge, this work is the first to report such advanced line-shape parameters of both studied molecular systems in this spectral region.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109748"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531874","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: 2026-01-02DOI: 10.1016/j.jqsrt.2025.109798
Franck Thibault, Kevin M. Dunseath
We use previously calculated generalized spectroscopic cross sections over a grid of relative collisional kinetic energies to investigate the temperature dependence of line shape parameters. This dependence, for the thermally averaged pressure broadening and shift parameters and also for the complex Dicke diffusion-type collision integral, is readily obtained by fitting the relevant quantities using a polynomial expansion in kinetic energy. Using a simple or double power law in kinetic energy we also investigate the general speed dependence of the pressure broadening and shift coefficients. In addition, we study the temperature dependence of the line shape parameters which characterize an assumed quadratic speed dependence of these coefficients, as implemented in the modified Hartmann–Tran profile and recommended by the HITRAN database.
{"title":"Temperature dependence of line shape parameters from the kinetic energy dependence of spectroscopic cross sections","authors":"Franck Thibault, Kevin M. Dunseath","doi":"10.1016/j.jqsrt.2025.109798","DOIUrl":"10.1016/j.jqsrt.2025.109798","url":null,"abstract":"<div><div>We use previously calculated generalized spectroscopic cross sections over a grid of relative collisional kinetic energies to investigate the temperature dependence of line shape parameters. This dependence, for the thermally averaged pressure broadening and shift parameters and also for the complex Dicke diffusion-type collision integral, is readily obtained by fitting the relevant quantities using a polynomial expansion in kinetic energy. Using a simple or double power law in kinetic energy we also investigate the general speed dependence of the pressure broadening and shift coefficients. In addition, we study the temperature dependence of the line shape parameters which characterize an assumed quadratic speed dependence of these coefficients, as implemented in the modified Hartmann–Tran profile and recommended by the HITRAN database.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"352 ","pages":"Article 109798"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145894097","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: 2025-11-18DOI: 10.1016/j.jqsrt.2025.109755
M. Klempka , M. Elantkowska , B. Furmann , J. Ruczkowski , P. Głowacki , S. Mieloch , D. Stefańska
The paper presents the results of the fine structure (fs) and the hyperfine structure (hfs) analysis of even-parity configuration levels of neutral lutetium (Lu I). The experimental results, obtained within this study using laser-induced fluorescence (LIF) spectroscopy or Fourier transform spectra, led to determination of the hfs constants for 17 levels, 5 of them evaluated for the first time. Using these new values, along with all the data available in the literature, we performed a semi-empirical parametric study of the fs and the hfs for the system of 147 even-parity configurations. A mean error of cm−1 for 174 energy levels was obtained. A very good consistency between the calculated and measured values was achieved for magnetic dipole constants (A); for electric quadrupole constants (B) the respective agreement was only slightly worse. For unknown electronic levels, predicted values of the level energies, Landé factors and the hfs constants are presented.
{"title":"Experimental and semi-empirical studies of the fine and the hyperfine structure of even-parity configuration system of atomic lutetium","authors":"M. Klempka , M. Elantkowska , B. Furmann , J. Ruczkowski , P. Głowacki , S. Mieloch , D. Stefańska","doi":"10.1016/j.jqsrt.2025.109755","DOIUrl":"10.1016/j.jqsrt.2025.109755","url":null,"abstract":"<div><div>The paper presents the results of the fine structure (<em>fs</em>) and the hyperfine structure (<em>hfs</em>) analysis of even-parity configuration levels of neutral lutetium (Lu I). The experimental results, obtained within this study using laser-induced fluorescence (LIF) spectroscopy or Fourier transform spectra, led to determination of the <em>hfs</em> constants for 17 levels, 5 of them evaluated for the first time. Using these new values, along with all the data available in the literature, we performed a semi-empirical parametric study of the <em>fs</em> and the <em>hfs</em> for the system of 147 even-parity configurations. A mean error of <span><math><mrow><mi>Δ</mi><mi>E</mi><mo>=</mo><mn>5</mn><mo>.</mo><mn>7</mn></mrow></math></span> cm<sup>−1</sup> for 174 energy levels was obtained. A very good consistency between the calculated and measured values was achieved for magnetic dipole constants (<em>A</em>); for electric quadrupole constants (<em>B</em>) the respective agreement was only slightly worse. For unknown electronic levels, predicted values of the level energies, Landé <span><math><msub><mrow><mi>g</mi></mrow><mrow><mi>J</mi></mrow></msub></math></span> factors and the <em>hfs</em> constants are presented.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109755"},"PeriodicalIF":1.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145546287","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号