The radial quadrature method is proposed recently for evaluating the beam shape coefficients (BSCs) of shaped beams, in which the BSCs are expressed in terms of integrals, infinite series and finite series as well. Previous study reveals that the BSCs expressed in finite series agree exactly with those obtained in the finite series technique and show blowing-ups for high-order partial waves, while the BSCs expressed in infinite series do not blow up. The paper presented here uncovers the reason behind these phenomena. It is found that the radial quadrature suppresses significantly the evanescent waves in the BSC evaluation.
{"title":"On radial quadrature method applied to spherical wave expansion of Gaussian beams","authors":"Siqi Tang , Jianqi Shen , Gérard Gouesbet , Leonardo A. Ambrosio","doi":"10.1016/j.jqsrt.2024.109290","DOIUrl":"10.1016/j.jqsrt.2024.109290","url":null,"abstract":"<div><div>The radial quadrature method is proposed recently for evaluating the beam shape coefficients (BSCs) of shaped beams, in which the BSCs are expressed in terms of integrals, infinite series and finite series as well. Previous study reveals that the BSCs expressed in finite series agree exactly with those obtained in the finite series technique and show blowing-ups for high-order partial waves, while the BSCs expressed in infinite series do not blow up. The paper presented here uncovers the reason behind these phenomena. It is found that the radial quadrature suppresses significantly the evanescent waves in the BSC evaluation.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"332 ","pages":"Article 109290"},"PeriodicalIF":2.3,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721650","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 : 2024-11-22DOI: 10.1016/j.jqsrt.2024.109292
Miroslav Kocifaj , Tomáš Novák , Igor Medveď
The optical properties of semi-transparent components used as multifunctional coatings or in various non-imaging devices are not always completely known a priori. The quality of plastic covers used in night sky brightness monitors, such as Sky Quality Meter (SQM), can deteriorate with age, causing initially transparent windows to become semi-transparent media that absorb and scatter light. We demonstrate here that the asymmetry parameter, single-scattering albedo, and volume extinction coefficient of such a diffusing optical element can be determined by measuring the light escaping from its outer interface.
Here we develop a simple model that allows for retrieval of the above parameters and can be applied to characterize various semi-transparent materials. The method is demonstrated for a particle-doped polycarbonate and Poly(methyl methacrylate) flat-plates of different thicknesses illuminated by a white light source. The spectral intensity of transmitted radiation is analyzed at discrete scattering angles for two samples of nearly the same optical properties except for the scattering asymmetry parameter. The samples sharing a number of similarities provide an ideal tool to test the method, because the angular structure of the scattered light can be interpreted in terms of a single optical parameter (while holding all other factors equal or nearly equal).
The method is useful for the optical diagnosis of covers on non-imaging devices as they age (e.g., SQMs). The optical properties of a plastic cover obtained from its measured spectral intensity distribution function are needed to interpret and correct the data gathered by still non-retired night sky scanners. Additionally, the method can assist in selecting the optimal optical covers for solar and other applications.
{"title":"Optical properties of semi-transparent sensor covers determined from their spectral intensity distribution function","authors":"Miroslav Kocifaj , Tomáš Novák , Igor Medveď","doi":"10.1016/j.jqsrt.2024.109292","DOIUrl":"10.1016/j.jqsrt.2024.109292","url":null,"abstract":"<div><div>The optical properties of semi-transparent components used as multifunctional coatings or in various non-imaging devices are not always completely known a priori. The quality of plastic covers used in night sky brightness monitors, such as Sky Quality Meter (SQM), can deteriorate with age, causing initially transparent windows to become semi-transparent media that absorb and scatter light. We demonstrate here that the asymmetry parameter, single-scattering albedo, and volume extinction coefficient of such a diffusing optical element can be determined by measuring the light escaping from its outer interface.</div><div>Here we develop a simple model that allows for retrieval of the above parameters and can be applied to characterize various semi-transparent materials. The method is demonstrated for a particle-doped polycarbonate and Poly(methyl methacrylate) flat-plates of different thicknesses illuminated by a white light source. The spectral intensity of transmitted radiation is analyzed at discrete scattering angles for two samples of nearly the same optical properties except for the scattering asymmetry parameter. The samples sharing a number of similarities provide an ideal tool to test the method, because the angular structure of the scattered light can be interpreted in terms of a single optical parameter (while holding all other factors equal or nearly equal).</div><div>The method is useful for the optical diagnosis of covers on non-imaging devices as they age (e.g., SQMs). The optical properties of a plastic cover obtained from its measured spectral intensity distribution function are needed to interpret and correct the data gathered by still non-retired night sky scanners. Additionally, the method can assist in selecting the optimal optical covers for solar and other applications.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"332 ","pages":"Article 109292"},"PeriodicalIF":2.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721651","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 : 2024-11-22DOI: 10.1016/j.jqsrt.2024.109285
L. Windholz , S. Kröger
A determination of the hyperfine structure constants of high lying energy levels of the Niobium (Nb) atom was performed using Fourier-transform spectra. The results obtained complete previous investigations using mainly laser spectroscopy [JQSRT (2020) 245, 106871, 106872, 106873]. In the present work, the hf constants A of altogether 144 levels could be determined, among them 55 levels for which these constants are reported for the first time. Now for nearly all known energy levels of atomic Nb the hyperfine constants A are available. Further the discovery of four previously unknown energy levels is reported.
{"title":"Systematic investigations of the hyperfine structure constants of Niobium I levels. Part IV: New results derived from Fourier-transform spectra, including the discovery of four new levels","authors":"L. Windholz , S. Kröger","doi":"10.1016/j.jqsrt.2024.109285","DOIUrl":"10.1016/j.jqsrt.2024.109285","url":null,"abstract":"<div><div>A determination of the hyperfine structure constants of high lying energy levels of the Niobium (Nb) atom was performed using Fourier-transform spectra. The results obtained complete previous investigations using mainly laser spectroscopy [JQSRT (2020) 245, 106871, 106872, 106873]. In the present work, the hf constants <em>A</em> of altogether 144 levels could be determined, among them 55 levels for which these constants are reported for the first time. Now for nearly all known energy levels of atomic Nb the hyperfine constants <em>A</em> are available. Further the discovery of four previously unknown energy levels is reported.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"332 ","pages":"Article 109285"},"PeriodicalIF":2.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745339","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 : 2024-11-21DOI: 10.1016/j.jqsrt.2024.109275
Spencer C. Barnes , Jesse W. Streicher , Ajay Krish, Ronald K. Hanson
<div><div>Development of a new ultraviolet (UV) laser absorption diagnostic has enabled the probing of nitric oxide (NO) in the second excited vibrational state (v” = 2) for inferences of quantum-state-specific number density and vibrational temperature time-histories. Spectroscopic modeling informed the selection of the new 246.3222 nm wavelength, as this wavelength exhibits high sensitivity for thermometry in the 2000 – 8000 K temperature range. This 246.3222 nm absorption feature consists of contributions from the <span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>12</mn></mrow></msub><mrow><mo>(</mo><mn>24</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span>, <span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>11</mn></mrow></msub><mrow><mo>(</mo><mn>15</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span>, <span><math><mrow><msub><mrow><mi>Q</mi></mrow><mrow><mn>22</mn></mrow></msub><mrow><mo>(</mo><mn>24</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span>, and <span><math><mrow><msub><mrow><mi>Q</mi></mrow><mrow><mn>21</mn></mrow></msub><mrow><mo>(</mo><mn>15</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span> transitions all originating in the v” = 2 state. Absorption cross-sections at this selected wavelength were measured in reflected shock experiments for sweeps of both wavelength and temperature. The wavelength sweep investigated cross-sections over a 246.3202 – 246.3246 nm range at 4590 K, and the temperature sweep measured cross-sections over a 2500 – 7500 K range at the peak of the absorption feature (246.3222 nm). Cross-section results agree with the Stanford NO gamma-band model to within <span><math><mo>±</mo></math></span>5%, confirming the use of the model for subsequent thermometry studies. Thermometry was demonstrated in reflected shock experiments probing the vibrational relaxation and chemical reactions in 2% NO diluted in either argon (Ar) or nitrogen (N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>). These experiments leverage previous UV laser absorption diagnostics that probe NO in the ground vibrational state (v” = 0) using the R<sub>11</sub>(26.5), R<sub>12</sub>(34.5), Q<sub>21</sub>(26.5) , and Q<sub>22</sub>(34.5) transitions near 224.8155 nm and the Q<sub>11</sub>(12.5) , R<sub>12</sub>(19.5) , P<sub>21</sub>(12.5) , and Q<sub>22</sub>(19.5) transitions near 226.1026 nm, which were studied in Ref. <span><span>[1]</span></span>. The combination of the new diagnostic wavelength with previously validated diagnostics yields low-uncertainty vibrational temperature time-histories that are in excellent agreement with previously inferred vibrational relaxation time results from Refs. <span><span>[2]</span></span> and <span><span>[3]</span></span>. Future work will apply this two-color nitric oxide vibrational temperature diagnostic to probe the vibrational temperature of NO formed in high-temperature, shock-heated air at conditions relevant to
{"title":"Development and demonstration of a two-color nitric oxide vibrational temperature diagnostic using spectrally-resolved ultraviolet laser absorption","authors":"Spencer C. Barnes , Jesse W. Streicher , Ajay Krish, Ronald K. Hanson","doi":"10.1016/j.jqsrt.2024.109275","DOIUrl":"10.1016/j.jqsrt.2024.109275","url":null,"abstract":"<div><div>Development of a new ultraviolet (UV) laser absorption diagnostic has enabled the probing of nitric oxide (NO) in the second excited vibrational state (v” = 2) for inferences of quantum-state-specific number density and vibrational temperature time-histories. Spectroscopic modeling informed the selection of the new 246.3222 nm wavelength, as this wavelength exhibits high sensitivity for thermometry in the 2000 – 8000 K temperature range. This 246.3222 nm absorption feature consists of contributions from the <span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>12</mn></mrow></msub><mrow><mo>(</mo><mn>24</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span>, <span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>11</mn></mrow></msub><mrow><mo>(</mo><mn>15</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span>, <span><math><mrow><msub><mrow><mi>Q</mi></mrow><mrow><mn>22</mn></mrow></msub><mrow><mo>(</mo><mn>24</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span>, and <span><math><mrow><msub><mrow><mi>Q</mi></mrow><mrow><mn>21</mn></mrow></msub><mrow><mo>(</mo><mn>15</mn><mo>.</mo><mn>5</mn><mo>)</mo></mrow></mrow></math></span> transitions all originating in the v” = 2 state. Absorption cross-sections at this selected wavelength were measured in reflected shock experiments for sweeps of both wavelength and temperature. The wavelength sweep investigated cross-sections over a 246.3202 – 246.3246 nm range at 4590 K, and the temperature sweep measured cross-sections over a 2500 – 7500 K range at the peak of the absorption feature (246.3222 nm). Cross-section results agree with the Stanford NO gamma-band model to within <span><math><mo>±</mo></math></span>5%, confirming the use of the model for subsequent thermometry studies. Thermometry was demonstrated in reflected shock experiments probing the vibrational relaxation and chemical reactions in 2% NO diluted in either argon (Ar) or nitrogen (N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>). These experiments leverage previous UV laser absorption diagnostics that probe NO in the ground vibrational state (v” = 0) using the R<sub>11</sub>(26.5), R<sub>12</sub>(34.5), Q<sub>21</sub>(26.5) , and Q<sub>22</sub>(34.5) transitions near 224.8155 nm and the Q<sub>11</sub>(12.5) , R<sub>12</sub>(19.5) , P<sub>21</sub>(12.5) , and Q<sub>22</sub>(19.5) transitions near 226.1026 nm, which were studied in Ref. <span><span>[1]</span></span>. The combination of the new diagnostic wavelength with previously validated diagnostics yields low-uncertainty vibrational temperature time-histories that are in excellent agreement with previously inferred vibrational relaxation time results from Refs. <span><span>[2]</span></span> and <span><span>[3]</span></span>. Future work will apply this two-color nitric oxide vibrational temperature diagnostic to probe the vibrational temperature of NO formed in high-temperature, shock-heated air at conditions relevant to","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"332 ","pages":"Article 109275"},"PeriodicalIF":2.3,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745340","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 : 2024-11-20DOI: 10.1016/j.jqsrt.2024.109287
Sergey A. Astashkevich , Anatoly A. Kudryavtsev
A modeling of the photoplasma in a slab cell filled with a sodium vapor and argon mixture one-sided irradiated by a uniform radiation flux was carried out. This study was performed for a spatially heterogeneous distribution of the resonance level density, unlike our previous works. An analytical form of this distribution for the slab available in the literature was used. The present investigation was performed at the sodium vapor pressure PNa=0.005−0.3 torr and the ratio of argon and sodium pressures PAr/PNa=102 for the spectral flux density F=5⋅102−5.2⋅104 Wm−2nm−1. A set of plasma chemical reactions, radiation transfer and charge transport were considered. The spatial profiles of densities of the sodium atomic levels, atomic and diatomic ions, the electron density and temperature, and the electric potential in the volume of the cell were obtained from a self-consistent solution of the balance equations for densities of plasma components and the electron energy. It was established that spatial picture of the Na+ and Na2+ ion density fractions depends significantly on the cell conditions. Parameters of wall sheaths were calculated used formulas from the literature. Used these data and the obtained spatial profiles of electric potential, the dependencies of electromotive force (the potential difference between the illuminated and dark walls of the cell) on the sodium pressure and incidental spectral flux density were obtained. The maximal EMF value was 1.5 V for the PNa=0.05 torr and F=5.2⋅104 Wm−2nm−1. Obtained results can be used in the development of photo-electric converters.
{"title":"Modeling of photoplasma for creating EMF in slab cell one-sided irradiated by uniform radiation","authors":"Sergey A. Astashkevich , Anatoly A. Kudryavtsev","doi":"10.1016/j.jqsrt.2024.109287","DOIUrl":"10.1016/j.jqsrt.2024.109287","url":null,"abstract":"<div><div>A modeling of the photoplasma in a slab cell filled with a sodium vapor and argon mixture one-sided irradiated by a uniform radiation flux was carried out. This study was performed for a spatially heterogeneous distribution of the resonance level density, unlike our previous works. An analytical form of this distribution for the slab available in the literature was used. The present investigation was performed at the sodium vapor pressure <em>P</em><sub>Na</sub>=0.005−0.3 torr and the ratio of argon and sodium pressures <em>P</em><sub>Ar</sub>/<em>P</em><sub>Na</sub>=10<sup>2</sup> for the spectral flux density <em>F</em>=5⋅10<sup>2</sup>−5.2⋅10<sup>4</sup> Wm<sup>−2</sup>nm<sup>−1</sup>. A set of plasma chemical reactions, radiation transfer and charge transport were considered. The spatial profiles of densities of the sodium atomic levels, atomic and diatomic ions, the electron density and temperature, and the electric potential in the volume of the cell were obtained from a self-consistent solution of the balance equations for densities of plasma components and the electron energy. It was established that spatial picture of the Na<sup>+</sup> and Na<sub>2</sub><sup>+</sup> ion density fractions depends significantly on the cell conditions. Parameters of wall sheaths were calculated used formulas from the literature. Used these data and the obtained spatial profiles of electric potential, the dependencies of electromotive force (the potential difference between the illuminated and dark walls of the cell) on the sodium pressure and incidental spectral flux density were obtained. The maximal EMF value was 1.5 V for the <em>P</em><sub>Na</sub>=0.05 torr and <em>F</em>=5.2⋅10<sup>4</sup> Wm<sup>−2</sup>nm<sup>−1</sup>. Obtained results can be used in the development of photo-electric converters.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"332 ","pages":"Article 109287"},"PeriodicalIF":2.3,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745237","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 : 2024-11-19DOI: 10.1016/j.jqsrt.2024.109286
A.V. Nikitin , A.A. Solodov , A.E. Protasevich , M. Rey , A.M. Solodov , V.G. Tyuterev
Four spectra of methane in natural isotopic abundance in the 900–1050 cm-1 region were recorded using a Fourier transform spectrometer in Tomsk, Russia, with long optical paths 167 m and 1058 m at temperatures 28 and 51 °C. Line positions and intensities were retrieved by non-linear least-squares curve-fitting procedures and analyzed using effective Hamiltonian and effective dipole moment models. The enhanced absorption at long paths permitted to measure new transitions: in cold bands up to Jmax = 28 and in hot bands up to Jmax = 20. The new experimental line list contains line positions and intensities for 2570 features. Quantum assignments were made for 1246 lines of the main isotopologue 12CH4. Comparisons of the theoretical absorption simulations with experimental spectra revealed a considerable improvement compared to the HITRAN2020 database. All assigned 1246 line positions were fitted to RMS standard deviations of 0.00065 cm-1.
{"title":"Improved line list of methane in the 900–1050 cm-1 region","authors":"A.V. Nikitin , A.A. Solodov , A.E. Protasevich , M. Rey , A.M. Solodov , V.G. Tyuterev","doi":"10.1016/j.jqsrt.2024.109286","DOIUrl":"10.1016/j.jqsrt.2024.109286","url":null,"abstract":"<div><div>Four spectra of methane in natural isotopic abundance in the 900–1050 cm<sup>-1</sup> region were recorded using a Fourier transform spectrometer in Tomsk, Russia, with long optical paths 167 m and 1058 m at temperatures 28 and 51 °C. Line positions and intensities were retrieved by non-linear least-squares curve-fitting procedures and analyzed using effective Hamiltonian and effective dipole moment models. The enhanced absorption at long paths permitted to measure new transitions: in cold bands up to <em>J</em><sub>max</sub> = 28 and in hot bands up to <em>J</em><sub>max</sub> = 20. The new experimental line list contains line positions and intensities for 2570 features. Quantum assignments were made for 1246 lines of the main isotopologue <sup>12</sup>CH<sub>4</sub>. Comparisons of the theoretical absorption simulations with experimental spectra revealed a considerable improvement compared to the HITRAN2020 database. All assigned 1246 line positions were fitted to RMS standard deviations of 0.00065 cm<sup>-1</sup>.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"331 ","pages":"Article 109286"},"PeriodicalIF":2.3,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723700","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 : 2024-11-18DOI: 10.1016/j.jqsrt.2024.109267
Alexander B. Stilgoe, Timo A. Nieminen, Halina Rubinsztein-Dunlop
T-matrix methods, with incident and scattered fields described as sums of multipolar fields, are attractive computational methods for many scattering problems due to their versatility, accuracy, and computational efficiency, especially for repeated calculations. However, numerical difficulties often hamper their use for non-spherical particles with large aspect ratios. Further, even if far-field scattering can be accurately calculated, it can be impossible to accurately calculate near-fields. The use of spheroidal wavefunctions, instead of the commonly-used spherical wavefunctions, can be a useful solution for these problems. However, the mathematical complexity of spheroidal wavefunctions, and the challenging task of accurate numerical calculation of them, are significant barriers to their use. We have developed a computational package of MATLAB routines for performing electromagnetic scattering calculations using spheroidal wavefunctions. These allow the determination of light scattering by non-spherical particles with high aspect ratios that would be inaccessible for double precision calculation using spherical wavefunctions. We demonstrate that our codes can be successfully used for cylinders of aspect ratios from 1/10 and 10, and for metal nanoparticles. We include routines for interoperability with regular T-matrix codes and packages such as our optical tweezers toolbox.
T 矩阵方法将入射场和散射场描述为多极场之和，由于其通用性、精确性和计算效率，特别是在重复计算时，对许多散射问题来说都是极具吸引力的计算方法。然而，对于具有较大长宽比的非球形粒子，数值计算上的困难往往会阻碍它们的应用。此外，即使可以精确计算远场散射，也不可能精确计算近场。使用球面波函数，而不是常用的球面波函数，可以有效解决这些问题。然而，球面波函数的数学复杂性和精确数值计算的艰巨性是使用球面波函数的重大障碍。我们开发了一套 MATLAB 例程，用于使用球面波函数进行电磁散射计算。这些例程可以确定高纵横比的非球形粒子的光散射，而使用球形波函数进行双精度计算是无法实现这些散射的。我们证明，我们的代码可以成功用于长宽比为 1/10 到 10 的圆柱体以及金属纳米粒子。我们还提供了与常规 T 矩阵代码和软件包（如我们的光学镊子工具箱）互操作的例程。
{"title":"Computational toolbox for scattering of focused light from flattened or elongated particles using spheroidal wavefunctions","authors":"Alexander B. Stilgoe, Timo A. Nieminen, Halina Rubinsztein-Dunlop","doi":"10.1016/j.jqsrt.2024.109267","DOIUrl":"10.1016/j.jqsrt.2024.109267","url":null,"abstract":"<div><div>T-matrix methods, with incident and scattered fields described as sums of multipolar fields, are attractive computational methods for many scattering problems due to their versatility, accuracy, and computational efficiency, especially for repeated calculations. However, numerical difficulties often hamper their use for non-spherical particles with large aspect ratios. Further, even if far-field scattering can be accurately calculated, it can be impossible to accurately calculate near-fields. The use of spheroidal wavefunctions, instead of the commonly-used spherical wavefunctions, can be a useful solution for these problems. However, the mathematical complexity of spheroidal wavefunctions, and the challenging task of accurate numerical calculation of them, are significant barriers to their use. We have developed a computational package of MATLAB routines for performing electromagnetic scattering calculations using spheroidal wavefunctions. These allow the determination of light scattering by non-spherical particles with high aspect ratios that would be inaccessible for double precision calculation using spherical wavefunctions. We demonstrate that our codes can be successfully used for cylinders of aspect ratios from 1/10 and 10, and for metal nanoparticles. We include routines for interoperability with regular T-matrix codes and packages such as our optical tweezers toolbox.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"331 ","pages":"Article 109267"},"PeriodicalIF":2.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696397","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 : 2024-11-18DOI: 10.1016/j.jqsrt.2024.109274
B. Furmann, M. Klempka, S. Mieloch, D. Stefańska, P. Głowacki
The paper presents the results of measurements of the hyperfine structure for electronic levels belonging to odd configurations in the terbium atom with a small quantum number . Laser spectroscopy with laser-induced fluorescence detection was used in the measurements. The hyperfine structure of 32 terbium lines was measured in three spectral regions. The hyperfine structure constants were determined for 20 levels with quantum number values between 1/2 and 7/2, of which 13 levels have not been studied so far. For the remaining 7 levels, the precision of the constants was improved.
{"title":"Hyperfine structure odd-parity configurations of the terbium atom, Part I: Levels with small J","authors":"B. Furmann, M. Klempka, S. Mieloch, D. Stefańska, P. Głowacki","doi":"10.1016/j.jqsrt.2024.109274","DOIUrl":"10.1016/j.jqsrt.2024.109274","url":null,"abstract":"<div><div>The paper presents the results of measurements of the hyperfine structure for electronic levels belonging to odd configurations in the terbium atom with a small quantum number <span><math><mi>J</mi></math></span>. Laser spectroscopy with laser-induced fluorescence detection was used in the measurements. The hyperfine structure of 32 terbium lines was measured in three spectral regions. The hyperfine structure constants were determined for 20 levels with quantum number <span><math><mi>J</mi></math></span> values between 1/2 and 7/2, of which 13 levels have not been studied so far. For the remaining 7 levels, the precision of the constants was improved.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"332 ","pages":"Article 109274"},"PeriodicalIF":2.3,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696401","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 : 2024-11-17DOI: 10.1016/j.jqsrt.2024.109268
Yuri Eremin, Vladimir Lopushenko
Understanding and accounting for quantum effects in nanoplasmonics is essential for accurate modeling and design of nanophotonic devices. In this paper, we investigate the influence of such quantum effects as spatial nonlocality and splitting of the wave function of conduction electrons near the surface of plasmonic nanoparticles on the extinction cross-section and the field enhancement factor. We apply the theory of generalized nonlocal optical response (GNOR) to describe the spatial nonlocality of noble metal particles. To consider the behavior of electrons near the metal–dielectric interface, mesoscopic boundary conditions are used, including the surface response functions (SRF) - the Feibelman parameters. We use the discrete source method (DSM), allowing for numerical analysis of the scattering problems taking into account quantum effects in the frame of both theories. The application of both GNOR and SRF approaches leads to a decrease in the amplitude of the plasmon resonance compared to the classical Maxwell theory and its shift to the shorter wavelength region (blue shift). The simulation results demonstrate significant differences between the two theories explaining the quantum effects arising in non-spherical plasmonic nanoparticles located in a dense environment. Specifically, compared with GNOR theory, SRF predicts a larger field enhancement. We found that quantum nonlocal effects are more significant for the enhancement factor at the particle surface than for the extinction cross-section. In addition, it was discovered that a denser environment leads to a significant increase in the blue shift of the plasmonic peak.
{"title":"Comparative analysis of theories accounting for quantum effects in plasmonic nanoparticles","authors":"Yuri Eremin, Vladimir Lopushenko","doi":"10.1016/j.jqsrt.2024.109268","DOIUrl":"10.1016/j.jqsrt.2024.109268","url":null,"abstract":"<div><div>Understanding and accounting for quantum effects in nanoplasmonics is essential for accurate modeling and design of nanophotonic devices. In this paper, we investigate the influence of such quantum effects as spatial nonlocality and splitting of the wave function of conduction electrons near the surface of plasmonic nanoparticles on the extinction cross-section and the field enhancement factor. We apply the theory of generalized nonlocal optical response (GNOR) to describe the spatial nonlocality of noble metal particles. To consider the behavior of electrons near the metal–dielectric interface, mesoscopic boundary conditions are used, including the surface response functions (SRF) - the Feibelman parameters. We use the discrete source method (DSM), allowing for numerical analysis of the scattering problems taking into account quantum effects in the frame of both theories. The application of both GNOR and SRF approaches leads to a decrease in the amplitude of the plasmon resonance compared to the classical Maxwell theory and its shift to the shorter wavelength region (blue shift). The simulation results demonstrate significant differences between the two theories explaining the quantum effects arising in non-spherical plasmonic nanoparticles located in a dense environment. Specifically, compared with GNOR theory, SRF predicts a larger field enhancement. We found that quantum nonlocal effects are more significant for the enhancement factor at the particle surface than for the extinction cross-section. In addition, it was discovered that a denser environment leads to a significant increase in the blue shift of the plasmonic peak.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"331 ","pages":"Article 109268"},"PeriodicalIF":2.3,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696399","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 : 2024-11-17DOI: 10.1016/j.jqsrt.2024.109269
Mikko Vuori, Antti Penttilä, Karri Muinonen, Heikki Suhonen, Joel Jääskeläinen
Sample properties such as shape and size can be studied via light scattering, if the material complex refractive index is known. A numerical method which utilizes laboratory measurements for deriving the complex refractive index of a mm-sized single particle is introduced. The laboratory measurements are carried out using a scatterometer that measures the intensity of polarized light scattered from an acoustically levitated sample in a fixed orientation as a function of scattering angle. To obtain the complex refractive index of the particle, measurements were compared to simulations done using a newly modified SIRIS4 Fixed Orientation geometric optics code. The real and imaginary part of the complex refractive index were varied in the simulations to find the best match between measurements and simulations. The complex refractive index of a levitated single particle was successfully derived in a specific wavelength using two different methods of translating sample orientation from measurements to simulations. For the first time, scattering matrix results from a measurement of a levitated mm-sized single particle in a fixed orientation were compared to light scattering simulations. The complex refractive index of a glass particle was derived successfully, verifying our method of refractive index retrieval from such measurements.
{"title":"Complex refractive index from scattering measurements for an acoustically levitated single particle","authors":"Mikko Vuori, Antti Penttilä, Karri Muinonen, Heikki Suhonen, Joel Jääskeläinen","doi":"10.1016/j.jqsrt.2024.109269","DOIUrl":"10.1016/j.jqsrt.2024.109269","url":null,"abstract":"<div><div>Sample properties such as shape and size can be studied via light scattering, if the material complex refractive index is known. A numerical method which utilizes laboratory measurements for deriving the complex refractive index of a mm-sized single particle is introduced. The laboratory measurements are carried out using a <span><math><mrow><mn>4</mn><mi>π</mi></mrow></math></span> scatterometer that measures the intensity of polarized light scattered from an acoustically levitated sample in a fixed orientation as a function of scattering angle. To obtain the complex refractive index of the particle, measurements were compared to simulations done using a newly modified SIRIS4 Fixed Orientation geometric optics code. The real and imaginary part of the complex refractive index were varied in the simulations to find the best match between measurements and simulations. The complex refractive index of a levitated single particle was successfully derived in a specific wavelength using two different methods of translating sample orientation from measurements to simulations. For the first time, scattering matrix results from a measurement of a levitated mm-sized single particle in a fixed orientation were compared to light scattering simulations. The complex refractive index of a glass particle was derived successfully, verifying our method of refractive index retrieval from such measurements.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"331 ","pages":"Article 109269"},"PeriodicalIF":2.3,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696398","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}
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