Pub Date : 2024-11-01DOI: 10.1016/j.jqsrt.2024.109244
Haifa Alali , Yong-Le Pan , Aimable Kalume , Yongxiang Hu , Yehor Surkov , Yuriy Shkuratov , Gorden Videen , Chuji Wang
The circular intensity differential scattering (CIDS), which is the normalized Mueller matrix element -S14/S11, has been measured from single biological particles as a function of scattering angle. CIDS is valuable for its potential in detecting chiral particles that may include the helical structures of DNA or RNA molecules in biological samples, and as such is a potential method for detecting biological particles. Optical trapping is employed to levitate single particles within a custom-designed elliptical reflector for CIDS measurements. The advantage of optical levitation in light-scattering measurements is that single particles can be suspended in air with sufficient working distance to prevent interference from the suspending apparatus. To measure the phase function, the reflector is used to collect the angle-dependent scattering signals. We demonstrated that we can obtain two-dimensional angular optical scattering (TAOS) patterns that cover a wide angular range from single levitated particles. These TAOS patterns are generated using 532 nm illumination of left-handed and right-handed circular polarizations and recorded from trapped single particles (silica, English Oak, Ragweed, Mulberry, Glycine, and l-Aspartic acid).
{"title":"Measurement of circular intensity differential scattering (CIDS) from single optically trapped biological particles","authors":"Haifa Alali , Yong-Le Pan , Aimable Kalume , Yongxiang Hu , Yehor Surkov , Yuriy Shkuratov , Gorden Videen , Chuji Wang","doi":"10.1016/j.jqsrt.2024.109244","DOIUrl":"10.1016/j.jqsrt.2024.109244","url":null,"abstract":"<div><div>The circular intensity differential scattering (CIDS), which is the normalized Mueller matrix element -S<sub>14</sub>/S<sub>11</sub>, has been measured from single biological particles as a function of scattering angle. CIDS is valuable for its potential in detecting chiral particles that may include the helical structures of DNA or RNA molecules in biological samples, and as such is a potential method for detecting biological particles. Optical trapping is employed to levitate single particles within a custom-designed elliptical reflector for CIDS measurements. The advantage of optical levitation in light-scattering measurements is that single particles can be suspended in air with sufficient working distance to prevent interference from the suspending apparatus. To measure the phase function, the reflector is used to collect the angle-dependent scattering signals. We demonstrated that we can obtain two-dimensional angular optical scattering (TAOS) patterns that cover a wide angular range from single levitated particles. These TAOS patterns are generated using 532 nm illumination of left-handed and right-handed circular polarizations and recorded from trapped single particles (silica, English Oak, Ragweed, Mulberry, Glycine, and <span>l</span>-Aspartic acid).</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109244"},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661292","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 : 2024-10-31DOI: 10.1016/j.jqsrt.2024.109233
Jia Wu , Baodong Gai , Shu Hu , Zihao Liu , Tao Li , Xianglong Cai , Ming Xu , Dongdong Xu , Shutong He , Yannan Tan , Jialiang Zhang , Jingwei Guo
Preparation of metastable Kr atoms in the 5s[3/2]2 level via laser-induced ionization has been achieved. The temporal evolution of the intensity of Kr atomic spectral lines at 760.15 nm, 811.29 nm, and 431.96 nm was used to elucidate the production mechanisms of metastable Kr atoms. These mechanisms primarily involve two processes: the “excitation + radiation” process, dominated by multiphoton excitation and initial plasma-induced electron impact excitation, and the “ion-electron recombination” process, governed by avalanche ionization. The decay time constants of Kr atomic spectral lines, corresponding to the “excitation + radiation” and “ion-electron recombination” processes respectively, were obtained experimentally under both strong and weak ionization conditions. The experiments revealed delay in preparations of metastable Kr atoms between these two processes. To reduce the loss of metastable Kr atoms and effectively utilize their peak concentration, we drew inspiration from metastable rare gas lasers and proposed the “cycling” idea to keep metastable Kr atoms produced by these two processes as synchronized as possible. We used 811.29 nm laser to excite metastable Kr atoms generated rapidly during the “excitation + radiation” stage to the 5p[5/2]3 level. The Kr atoms returned to the 5s[3/2]2 level through spontaneous radiation, merging with metastable Kr atoms that were slowly produced during the “ion-electron recombination” stage. We hope that the “cycling” idea can shorten the delay in preparations of metastable Kr atoms from both processes and enhance the peak concentration of metastable Kr atoms. However, the experimental results didn't meet expectations, as we observed a decrease in the 811.29 nm fluorescence after laser excitation, attributed to the accumulation of 5p[5/2]3 level Kr atoms. These atoms undergo energy pooling to populate the 4d’[3/2]1 and 5d[7/2]3 levels, followed by absorption of 811.29 nm laser energy leading to photoionization. Reducing the concentration of 5p[5/2]3 level Kr atoms helps mitigate the reionization issue.
{"title":"Mechanism of metastable krypton atom preparation via laser-induced ionization","authors":"Jia Wu , Baodong Gai , Shu Hu , Zihao Liu , Tao Li , Xianglong Cai , Ming Xu , Dongdong Xu , Shutong He , Yannan Tan , Jialiang Zhang , Jingwei Guo","doi":"10.1016/j.jqsrt.2024.109233","DOIUrl":"10.1016/j.jqsrt.2024.109233","url":null,"abstract":"<div><div>Preparation of metastable Kr atoms in the 5s[3/2]<sub>2</sub> level via laser-induced ionization has been achieved. The temporal evolution of the intensity of Kr atomic spectral lines at 760.15 nm, 811.29 nm, and 431.96 nm was used to elucidate the production mechanisms of metastable Kr atoms. These mechanisms primarily involve two processes: the “excitation + radiation” process, dominated by multiphoton excitation and initial plasma-induced electron impact excitation, and the “ion-electron recombination” process, governed by avalanche ionization. The decay time constants of Kr atomic spectral lines, corresponding to the “excitation + radiation” and “ion-electron recombination” processes respectively, were obtained experimentally under both strong and weak ionization conditions. The experiments revealed delay in preparations of metastable Kr atoms between these two processes. To reduce the loss of metastable Kr atoms and effectively utilize their peak concentration, we drew inspiration from metastable rare gas lasers and proposed the “cycling” idea to keep metastable Kr atoms produced by these two processes as synchronized as possible. We used 811.29 nm laser to excite metastable Kr atoms generated rapidly during the “excitation + radiation” stage to the 5p[5/2]<sub>3</sub> level. The Kr atoms returned to the 5s[3/2]<sub>2</sub> level through spontaneous radiation, merging with metastable Kr atoms that were slowly produced during the “ion-electron recombination” stage. We hope that the “cycling” idea can shorten the delay in preparations of metastable Kr atoms from both processes and enhance the peak concentration of metastable Kr atoms. However, the experimental results didn't meet expectations, as we observed a decrease in the 811.29 nm fluorescence after laser excitation, attributed to the accumulation of 5p[5/2]<sub>3</sub> level Kr atoms. These atoms undergo energy pooling to populate the 4d’[3/2]<sub>1</sub> and 5d[7/2]<sub>3</sub> levels, followed by absorption of 811.29 nm laser energy leading to photoionization. Reducing the concentration of 5p[5/2]<sub>3</sub> level Kr atoms helps mitigate the reionization issue.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109233"},"PeriodicalIF":2.3,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586036","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 : 2024-10-31DOI: 10.1016/j.jqsrt.2024.109229
Hongxu Li, Tao Ren, Changying Zhao
Hyperspectral absorption tomography has emerged as a promising technique for combustion diagnostics due to its rich spectral measurements. However, the non-linear and ill-posed nature of the inverse problem makes obtaining accurate results challenging. This paper proposes a novel application of a physics-informed neural network to address the non-linear inverse problem in hyperspectral absorption spectroscopy. This method utilizes physical laws and measurement data to guide the neural network in finding the optimal solution, without requiring training data. To demonstrate its capabilities, the physics-informed neural network is employed to retrieve temperature and CO mole fraction fields in axisymmetric laminar diffusion flames via TDLAS (tunable diode laser absorption spectroscopy). The developed neural network is applied to resolve the spatial distributions from the spectral dimensions, requiring fewer spatial measurements for directly retrieving temperature and CO mole fraction profiles. We investigate the minimum radial projections needed for accurate retrievals and evaluate the model’s robustness to random noise through the inversion of a simulated flame. The developed model is further applied to reconstruct the temperature and CO mole fraction fields for an experimentally measured flame. Our results demonstrate that the proposed model maintains high retrieval accuracy even with limited, noisy data. This work highlights the potential of the physics-informed neural network for robust solutions to non-linear laser absorption tomography problems in scientific and engineering applications.
{"title":"A physics-informed neural network for non-linear laser absorption tomography","authors":"Hongxu Li, Tao Ren, Changying Zhao","doi":"10.1016/j.jqsrt.2024.109229","DOIUrl":"10.1016/j.jqsrt.2024.109229","url":null,"abstract":"<div><div>Hyperspectral absorption tomography has emerged as a promising technique for combustion diagnostics due to its rich spectral measurements. However, the non-linear and ill-posed nature of the inverse problem makes obtaining accurate results challenging. This paper proposes a novel application of a physics-informed neural network to address the non-linear inverse problem in hyperspectral absorption spectroscopy. This method utilizes physical laws and measurement data to guide the neural network in finding the optimal solution, without requiring training data. To demonstrate its capabilities, the physics-informed neural network is employed to retrieve temperature and CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> mole fraction fields in axisymmetric laminar diffusion flames via <span><math><mrow><mn>4</mn><mo>.</mo><mn>3</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> TDLAS (tunable diode laser absorption spectroscopy). The developed neural network is applied to resolve the spatial distributions from the spectral dimensions, requiring fewer spatial measurements for directly retrieving temperature and CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> mole fraction profiles. We investigate the minimum radial projections needed for accurate retrievals and evaluate the model’s robustness to random noise through the inversion of a simulated flame. The developed model is further applied to reconstruct the temperature and CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> mole fraction fields for an experimentally measured flame. Our results demonstrate that the proposed model maintains high retrieval accuracy even with limited, noisy data. This work highlights the potential of the physics-informed neural network for robust solutions to non-linear laser absorption tomography problems in scientific and engineering applications.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109229"},"PeriodicalIF":2.3,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586037","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 : 2024-10-31DOI: 10.1016/j.jqsrt.2024.109243
Ihsan Farouki, Aamir Farooq, Bassam Dally
A mathematical method to enable absorption cross-section measurements using an optical cell with a non-uniform temperature distribution is formulated, validated and experimentally demonstrated in this study. The motivation of the proposed method is to facilitate high-temperature spectroscopic studies in the long-wavelength mid-IR region, and to offer an alternative to highly engineered optical cells. The method is based on virtual segmentation of the non-uniform temperature field within an optical cell into bins, each having a sufficiently uniform temperature. By collecting a set of absorbance measurements corresponding to unique temperature profiles and expressing the temperature dependence of the absorption cross-section in terms of a model with limited number of unknowns, a closed-form system of equations is obtained which can be solved to evaluate absorption cross-sections. It is shown, through a set of simulated validation cases, that modeling the temperature dependence in terms of a third order polynomial results in accurate reconstruction of the cross-section spectra for a wide range of cases. Piece-wise polynomials and an alternative nonlinear model are proposed for improved accuracy and to model potentially complex temperature dependencies of the absorption cross-sections. To demonstrate the application of the proposed method, an optical cell with a non-uniform temperature profile was used to measure the cross-section spectra of methane over 1280 – 1330 cm-1 at temperatures up to 523 K. The proposed method is expected to be highly useful in collecting spectroscopic data at high temperatures particularly in the mid-infrared region.
本研究提出了一种数学方法，可利用温度分布不均匀的光学池测量吸收截面，该方法经过验证和实验演示。提出该方法的动机是促进长波长中红外区域的高温光谱研究，并为高度工程化的光学池提供一种替代方法。该方法的基础是将光学池内的非均匀温度场虚拟分割成不同的区块，每个区块都有足够均匀的温度。通过收集一组与独特温度曲线相对应的吸光度测量值，并用一个未知数数量有限的模型来表示吸收截面的温度依赖性，就可以得到一个闭式方程组，通过求解该方程组就可以评估吸收截面。通过一组模拟验证案例表明，用三次多项式来表示温度依赖性模型，可以在多种情况下准确地重建横截面光谱。为了提高精确度，并对吸收截面潜在的复杂温度依赖性进行建模，提出了分段多项式和另一种非线性模型。为了演示所提方法的应用，我们使用了一个具有非均匀温度曲线的光学池来测量温度高达 523 K 的甲烷在 1280 - 1330 cm-1 范围内的横截面光谱。
{"title":"Measurement of high-temperature absorption cross-sections using an optical cell with a non-uniform temperature distribution","authors":"Ihsan Farouki, Aamir Farooq, Bassam Dally","doi":"10.1016/j.jqsrt.2024.109243","DOIUrl":"10.1016/j.jqsrt.2024.109243","url":null,"abstract":"<div><div>A mathematical method to enable absorption cross-section measurements using an optical cell with a non-uniform temperature distribution is formulated, validated and experimentally demonstrated in this study. The motivation of the proposed method is to facilitate high-temperature spectroscopic studies in the long-wavelength mid-IR region, and to offer an alternative to highly engineered optical cells. The method is based on virtual segmentation of the non-uniform temperature field within an optical cell into bins, each having a sufficiently uniform temperature. By collecting a set of absorbance measurements corresponding to unique temperature profiles and expressing the temperature dependence of the absorption cross-section in terms of a model with limited number of unknowns, a closed-form system of equations is obtained which can be solved to evaluate absorption cross-sections. It is shown, through a set of simulated validation cases, that modeling the temperature dependence in terms of a third order polynomial results in accurate reconstruction of the cross-section spectra for a wide range of cases. Piece-wise polynomials and an alternative nonlinear model are proposed for improved accuracy and to model potentially complex temperature dependencies of the absorption cross-sections. To demonstrate the application of the proposed method, an optical cell with a non-uniform temperature profile was used to measure the cross-section spectra of methane over 1280 – 1330 cm<sup>-1</sup> at temperatures up to 523 K. The proposed method is expected to be highly useful in collecting spectroscopic data at high temperatures particularly in the mid-infrared region.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109243"},"PeriodicalIF":2.3,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593973","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 : 2024-10-30DOI: 10.1016/j.jqsrt.2024.109255
Francesca Vitali , Stefania Stefani , Giuseppe Piccioni , Marcel Snels , Davide Grassi , David Biondi , Angelo Boccaccini
The Collision-Induced Absorption (CIA) fundamental band of H2 has been studied in the 3600–5500 cm−1 spectral range for temperatures ranging from 120 to 500 K for both a pure H2 gas and a H2-He mixture. We used a simulation chamber called PASSxS (Planetary Atmosphere System Simulation x Spectroscopy) developed at INAF/ISAC which contains a Multi-Pass cell interfaced with a Fourier Spectrometer, aligned to reach an optical path of 3.28 m. The H2-H2 and H2-He binary absorption coefficients (BACs) have been derived for seven temperatures in the chosen range and provided in tabular form, including the unexplored high-temperature range above 300 K. We also calculated the integral of the H2-H2 and H2-He experimental BACs in the reduced 4000–5000 cm−1 spectral range, finding a linear trend with temperature in both cases. The integrals have also been computed with larger uncertainties for the whole band, in the total 3600–5500 cm−1 spectral range including the band's wings, partially affected by the water vapor absorption. The integrals calculated over the whole and reduced spectral ranges are collected in tables. In addition, we performed measurements with a H2-He mix for different mixing ratios to explore possible deviations from the linear combination of the BACs. The experimental BACs have been shown in comparison with Abel and Borysow's ab initio models for a temperature of about 400 K, resulting in a good agreement over almost the whole spectral range, with a maximum deviation around the main peak of the band. Data and models also show a good agreement in the linear trend of the integrated BACs with temperature, apart from the H2-H2 Borysow's BACs, which follow a quadratic trend. Finally, we resolved all the interference dips, which were not taken into account by the existing theoretical models.
{"title":"New experimental measurements of the Collision Induced Absorptions of H2-H2 and H2-He in the 3600-5500 cm−1 spectral range from 120 to 500 K","authors":"Francesca Vitali , Stefania Stefani , Giuseppe Piccioni , Marcel Snels , Davide Grassi , David Biondi , Angelo Boccaccini","doi":"10.1016/j.jqsrt.2024.109255","DOIUrl":"10.1016/j.jqsrt.2024.109255","url":null,"abstract":"<div><div>The Collision-Induced Absorption (CIA) fundamental band of H<sub>2</sub> has been studied in the 3600–5500 cm<sup>−1</sup> spectral range for temperatures ranging from 120 to 500 K for both a pure H<sub>2</sub> gas and a H<sub>2</sub>-He mixture. We used a simulation chamber called PASSxS (Planetary Atmosphere System Simulation x Spectroscopy) developed at INAF/ISAC which contains a Multi-Pass cell interfaced with a Fourier Spectrometer, aligned to reach an optical path of 3.28 m. The H<sub>2</sub>-H<sub>2</sub> and H<sub>2</sub>-He binary absorption coefficients (BACs) have been derived for seven temperatures in the chosen range and provided in tabular form, including the unexplored high-temperature range above 300 K. We also calculated the integral of the H<sub>2</sub>-H<sub>2</sub> and H<sub>2</sub>-He experimental BACs in the reduced 4000–5000 cm<sup>−1</sup> spectral range, finding a linear trend with temperature in both cases. The integrals have also been computed with larger uncertainties for the whole band, in the total 3600–5500 cm<sup>−1</sup> spectral range including the band's wings, partially affected by the water vapor absorption. The integrals calculated over the whole and reduced spectral ranges are collected in tables. In addition, we performed measurements with a H<sub>2</sub>-He mix for different mixing ratios to explore possible deviations from the linear combination of the BACs. The experimental BACs have been shown in comparison with Abel and Borysow's <em>ab initio</em> models for a temperature of about 400 K, resulting in a good agreement over almost the whole spectral range, with a maximum deviation around the main peak of the band. Data and models also show a good agreement in the linear trend of the integrated BACs with temperature, apart from the H<sub>2</sub>-H<sub>2</sub> Borysow's BACs, which follow a quadratic trend. Finally, we resolved all the interference dips, which were not taken into account by the existing theoretical models.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109255"},"PeriodicalIF":2.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-30DOI: 10.1016/j.jqsrt.2024.109234
Mofreh R. Zaghloul , Jacques Le Bourlot
Evaluation of the Voigt function, a convolution of a Lorentzian and a Gaussian profile, is essential in various fields such as spectroscopy, atmospheric science, and astrophysics. Efficient computation of the function is crucial, especially in applications where the function may be called for an enormous number of times. In this paper, we present a highly efficient novel algorithm and its Fortran90 implementation for the practical evaluation of the Voigt function with accuracy in the order of . The algorithm uses improved fits based on Chebyshev subinterval polynomial approximation for functions in two variables. The algorithm significantly outperforms widely-used competitive algorithms in the literature, in terms of computational speed, making it highly suitable for real-time applications and large-scale data processing tasks. The substantial improvement in efficiency positions the present algorithm and computer code as a valuable tool in relevant scientific domains. The algorithm has been adopted and implemented in the Meudon PDR code at Paris Observatory and is recommended for similar applications and simulation packages.
{"title":"A highly efficient Voigt program for line profile computation","authors":"Mofreh R. Zaghloul , Jacques Le Bourlot","doi":"10.1016/j.jqsrt.2024.109234","DOIUrl":"10.1016/j.jqsrt.2024.109234","url":null,"abstract":"<div><div>Evaluation of the Voigt function, a convolution of a Lorentzian and a Gaussian profile, is essential in various fields such as spectroscopy, atmospheric science, and astrophysics. Efficient computation of the function is crucial, especially in applications where the function may be called for an enormous number of times. In this paper, we present a highly efficient novel algorithm and its Fortran90 implementation for the practical evaluation of the Voigt function with accuracy in the order of <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span>. The algorithm uses improved fits based on Chebyshev subinterval polynomial approximation for functions in two variables. The algorithm significantly outperforms widely-used competitive algorithms in the literature, in terms of computational speed, making it highly suitable for real-time applications and large-scale data processing tasks. The substantial improvement in efficiency positions the present algorithm and computer code as a valuable tool in relevant scientific domains. The algorithm has been adopted and implemented in the Meudon PDR code at Paris Observatory and is recommended for similar applications and simulation packages.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109234"},"PeriodicalIF":2.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.jqsrt.2024.109226
Karri Muinonen , Ari Leppälä , Johannes Markkanen
We consider radiative transfer and coherent backscattering (RT-CB) in a discrete random medium of particles. The elementary scattering matrix of the medium conforms to the ensemble-averaged scattering matrix for nonspherical particles and their mirror particles, both in random orientation. We express the ensemble-averaged matrix, via spectral decomposition, as a linear superposition of four pure Mueller matrices, and enable RT-CB computations via an independent treatment of the pure matrices. We validate the method for sparsely and densely packed random media of spherical particles. For the case of sparse packing, we compare two different RT-CB approaches, one with explicit input of polydisperse spherical-particle characteristics and the other with input by decomposing the ensemble-averaged scattering matrix. The results are in agreement and reproduce markedly well the asymptotically exact results from the Fast Superposition -Matrix Method (FaSTMM). For the cases of dense packing, we compare the RT-CB to the FaSTMM by invoking the ensemble-averaged incoherent scattering matrix of volume elements as input for the RT-CB. For non-absorbing particles, the RT-CB agrees well with the FaSTMM. For strongly absorbing particles, there are deviations that underscore the need for further method development. In order to demonstrate the potential of the RT-CB, we compute multiple scattering for a sparsely packed spherical medium of nonspherical feldspar particles by utilizing their experimentally measured ensemble-averaged scattering phase matrix. Finally, we discuss future prospects for the RT-CB.
{"title":"Coherent backscattering in discrete random media of particle ensembles","authors":"Karri Muinonen , Ari Leppälä , Johannes Markkanen","doi":"10.1016/j.jqsrt.2024.109226","DOIUrl":"10.1016/j.jqsrt.2024.109226","url":null,"abstract":"<div><div>We consider radiative transfer and coherent backscattering (RT-CB) in a discrete random medium of particles. The elementary scattering matrix of the medium conforms to the ensemble-averaged scattering matrix for nonspherical particles and their mirror particles, both in random orientation. We express the ensemble-averaged matrix, via spectral decomposition, as a linear superposition of four pure Mueller matrices, and enable RT-CB computations via an independent treatment of the pure matrices. We validate the method for sparsely and densely packed random media of spherical particles. For the case of sparse packing, we compare two different RT-CB approaches, one with explicit input of polydisperse spherical-particle characteristics and the other with input by decomposing the ensemble-averaged scattering matrix. The results are in agreement and reproduce markedly well the asymptotically exact results from the Fast Superposition <span><math><mi>T</mi></math></span>-Matrix Method (FaSTMM). For the cases of dense packing, we compare the RT-CB to the FaSTMM by invoking the ensemble-averaged incoherent scattering matrix of volume elements as input for the RT-CB. For non-absorbing particles, the RT-CB agrees well with the FaSTMM. For strongly absorbing particles, there are deviations that underscore the need for further method development. In order to demonstrate the potential of the RT-CB, we compute multiple scattering for a sparsely packed spherical medium of nonspherical feldspar particles by utilizing their experimentally measured ensemble-averaged scattering phase matrix. Finally, we discuss future prospects for the RT-CB.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109226"},"PeriodicalIF":2.3,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.jqsrt.2024.109230
Zeyu Yan, Shengkai Wang
This study introduced a new model for quantitative analysis of the state-resolved laser-induced fluorescence signal of diatomic molecules, namely StaR-LIF. This model is built upon a master equation of the collisional-radiative transfer processes, which incorporated the latest data on the collisional energy transfer rates between individual spin- and parity-resolved rovibronic quantum levels, together with the most recent updates on the energy levels, line strengths and broadening/shift parameters of the relevant absorption and fluorescence transitions. To facilitate the use of this model, a web-based graphic user interface has been developed and made available at https://starlif.pku.edu.cn. Example applications of the current model have been demonstrated for NO, OH and CH, including parametric studies on the effects of variable pulse width and saturating excitation, as well as the temporal evolution of fluorescence spectrum during collisional transfer. The StaR-LIF model can provide quantitative modeling and analysis capabilities over a wide range of gasdynamic and excitation conditions, and promises to be useful in future LIF studies of complex reacting flows.
{"title":"StaR-LIF: State-resolved laser-induced fluorescence modeling for diatomic molecules","authors":"Zeyu Yan, Shengkai Wang","doi":"10.1016/j.jqsrt.2024.109230","DOIUrl":"10.1016/j.jqsrt.2024.109230","url":null,"abstract":"<div><div>This study introduced a new model for quantitative analysis of the state-resolved laser-induced fluorescence signal of diatomic molecules, namely StaR-LIF. This model is built upon a master equation of the collisional-radiative transfer processes, which incorporated the latest data on the collisional energy transfer rates between individual spin- and parity-resolved rovibronic quantum levels, together with the most recent updates on the energy levels, line strengths and broadening/shift parameters of the relevant absorption and fluorescence transitions. To facilitate the use of this model, a web-based graphic user interface has been developed and made available at <span><span>https://starlif.pku.edu.cn</span><svg><path></path></svg></span>. Example applications of the current model have been demonstrated for NO, OH and CH, including parametric studies on the effects of variable pulse width and saturating excitation, as well as the temporal evolution of fluorescence spectrum during collisional transfer. The StaR-LIF model can provide quantitative modeling and analysis capabilities over a wide range of gasdynamic and excitation conditions, and promises to be useful in future LIF studies of complex reacting flows.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109230"},"PeriodicalIF":2.3,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578363","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 : 2024-10-29DOI: 10.1016/j.jqsrt.2024.109246
Yury E. Geints, Ekaterina K. Panina
Microdispersed photocatalysts based on titanium dioxide (TiO2) in the form of hollow core-shell microspheres (microcapsules) with mesoporous structure are widely demanded in modern critical technologies related to the catalysis of various chemicals, solving environmental problems, and obtaining cheap fuel. To date, a number of experimental works are known, showing that geometrical parameters of microcapsules (size, shell thickness), as well as microstructural composition (nanosized metal additives, additional inner dielectric core- the "yolk") noticeably affect their photocatalytic activity. At the same time, a valuable physical description of the optical properties of porous microcapsules has not been presented in the literature so far. Using the finite element method, we perform a full-wave theoretical simulation of the optical field inside a hollow microsphere whose shell is randomly self-assembled from multiple TiO2 nanoparticles forming an irregular nanoporous structure. We provide a unified physical explanation of the published experimental data on the optical activity of titanium-dioxide microcapsules and show that the existing theoretical models do not always give a correct interpretation of the observed empirical behaviors.
{"title":"Theoretical study of size and shell composition effect of TiO2 core-shell mesoporous microsphere on UV absorption effectivity for photocatalytic application","authors":"Yury E. Geints, Ekaterina K. Panina","doi":"10.1016/j.jqsrt.2024.109246","DOIUrl":"10.1016/j.jqsrt.2024.109246","url":null,"abstract":"<div><div>Microdispersed photocatalysts based on titanium dioxide (TiO<sub>2</sub>) in the form of hollow core-shell microspheres (microcapsules) with mesoporous structure are widely demanded in modern critical technologies related to the catalysis of various chemicals, solving environmental problems, and obtaining cheap fuel. To date, a number of experimental works are known, showing that geometrical parameters of microcapsules (size, shell thickness), as well as microstructural composition (nanosized metal additives, additional inner dielectric core- the \"yolk\") noticeably affect their photocatalytic activity. At the same time, a valuable physical description of the optical properties of porous microcapsules has not been presented in the literature so far. Using the finite element method, we perform a full-wave theoretical simulation of the optical field inside a hollow microsphere whose shell is randomly self-assembled from multiple TiO<sub>2</sub> nanoparticles forming an irregular nanoporous structure. We provide a unified physical explanation of the published experimental data on the optical activity of titanium-dioxide microcapsules and show that the existing theoretical models do not always give a correct interpretation of the observed empirical behaviors.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109246"},"PeriodicalIF":2.3,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572722","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}
The present study uses a high-resolution Fourier Transform Spectrometer to provide data on the spectral line measurements of atomic bromine (Br I) in the 6000 – 12,000 cm‒1 range in the near-infrared spectral region. Bromine electrodeless discharge lamps (EDL) were prepared and utilized as light sources, while light detectors comprised InGaAs and Si diodes. A total of 302 spectral lines were detected using two different resolutions of 0.008 and 0.009 cm‒1, unveiling 104 lines reported for the first time. All observed lines have been assigned new center of gravity wavenumber values. We also present the unidentified lines and blended lines that appeared in our spectra. This study provides critical insights and data that enhance the understanding of atomic bromine spectroscopy.
{"title":"Br I spectral line measurements in the range 6000–12000 cm‒1: Part II","authors":"Chilukoti Ashok , Himal Bhatt , S.R. Vishwakarma , Arijit Sharma , M.N. Deo","doi":"10.1016/j.jqsrt.2024.109232","DOIUrl":"10.1016/j.jqsrt.2024.109232","url":null,"abstract":"<div><div>The present study uses a high-resolution Fourier Transform Spectrometer to provide data on the spectral line measurements of atomic bromine (Br I) in the 6000 – 12,000 cm<sup>‒1</sup> range in the near-infrared spectral region. Bromine electrodeless discharge lamps (EDL) were prepared and utilized as light sources, while light detectors comprised InGaAs and Si diodes. A total of 302 spectral lines were detected using two different resolutions of 0.008 and 0.009 cm<sup>‒1</sup>, unveiling 104 lines reported for the first time. All observed lines have been assigned new center of gravity wavenumber values. We also present the unidentified lines and blended lines that appeared in our spectra. This study provides critical insights and data that enhance the understanding of atomic bromine spectroscopy.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"330 ","pages":"Article 109232"},"PeriodicalIF":2.3,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572721","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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