K. Bijlsma, Lamberto Oltra, E. de Wit, Luc Assink, I. Rabadán, L. Méndez, R. Hoekstra
Over a wide and partly overlapping energy range, the single-electron capture cross-sections for collisions of metastable Sn2+(5s5p Po3) (Sn2+∗) ions with H2 molecules were measured (0.1–10 keV) and calculated (0.3–1000 keV). The semi-classical calculations use a close-coupling method on a basis of electronic wavefunctions of the (SnH2)2+ system. The experimental cross-sections were extracted from double collisions in a crossed-beam experiment of Sn3+ with H2. The measured capture cross-sections for Sn2+∗ show good agreement with the calculations between 2 and 10 keV, but increase toward lower energies, whereas the calculations decrease. Additional Landau–Zener calculations were performed and show that the inclusion of spin-orbit splitting cannot explain the large cross-sections at the lowest energies which we now assume to be likely due to vibrational effects in the molecular hydrogen target.
{"title":"Electron Capture from Molecular Hydrogen by Metastable Sn2+* Ions","authors":"K. Bijlsma, Lamberto Oltra, E. de Wit, Luc Assink, I. Rabadán, L. Méndez, R. Hoekstra","doi":"10.3390/atoms12020009","DOIUrl":"https://doi.org/10.3390/atoms12020009","url":null,"abstract":"Over a wide and partly overlapping energy range, the single-electron capture cross-sections for collisions of metastable Sn2+(5s5p Po3) (Sn2+∗) ions with H2 molecules were measured (0.1–10 keV) and calculated (0.3–1000 keV). The semi-classical calculations use a close-coupling method on a basis of electronic wavefunctions of the (SnH2)2+ system. The experimental cross-sections were extracted from double collisions in a crossed-beam experiment of Sn3+ with H2. The measured capture cross-sections for Sn2+∗ show good agreement with the calculations between 2 and 10 keV, but increase toward lower energies, whereas the calculations decrease. Additional Landau–Zener calculations were performed and show that the inclusion of spin-orbit splitting cannot explain the large cross-sections at the lowest energies which we now assume to be likely due to vibrational effects in the molecular hydrogen target.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139815151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Bijlsma, Lamberto Oltra, E. de Wit, Luc Assink, I. Rabadán, L. Méndez, R. Hoekstra
Over a wide and partly overlapping energy range, the single-electron capture cross-sections for collisions of metastable Sn2+(5s5p Po3) (Sn2+∗) ions with H2 molecules were measured (0.1–10 keV) and calculated (0.3–1000 keV). The semi-classical calculations use a close-coupling method on a basis of electronic wavefunctions of the (SnH2)2+ system. The experimental cross-sections were extracted from double collisions in a crossed-beam experiment of Sn3+ with H2. The measured capture cross-sections for Sn2+∗ show good agreement with the calculations between 2 and 10 keV, but increase toward lower energies, whereas the calculations decrease. Additional Landau–Zener calculations were performed and show that the inclusion of spin-orbit splitting cannot explain the large cross-sections at the lowest energies which we now assume to be likely due to vibrational effects in the molecular hydrogen target.
{"title":"Electron Capture from Molecular Hydrogen by Metastable Sn2+* Ions","authors":"K. Bijlsma, Lamberto Oltra, E. de Wit, Luc Assink, I. Rabadán, L. Méndez, R. Hoekstra","doi":"10.3390/atoms12020009","DOIUrl":"https://doi.org/10.3390/atoms12020009","url":null,"abstract":"Over a wide and partly overlapping energy range, the single-electron capture cross-sections for collisions of metastable Sn2+(5s5p Po3) (Sn2+∗) ions with H2 molecules were measured (0.1–10 keV) and calculated (0.3–1000 keV). The semi-classical calculations use a close-coupling method on a basis of electronic wavefunctions of the (SnH2)2+ system. The experimental cross-sections were extracted from double collisions in a crossed-beam experiment of Sn3+ with H2. The measured capture cross-sections for Sn2+∗ show good agreement with the calculations between 2 and 10 keV, but increase toward lower energies, whereas the calculations decrease. Additional Landau–Zener calculations were performed and show that the inclusion of spin-orbit splitting cannot explain the large cross-sections at the lowest energies which we now assume to be likely due to vibrational effects in the molecular hydrogen target.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139874982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Significant advances in Penning trap measurements of atomic masses and mass ratios of the proton, deuteron, triton, helion, and alpha-particle have occurred in the last five years. These include a measurement of the mass of the deuteron against 12C with 8.5 × 10−12 fractional uncertainty; resolution of vibrational levels of H2+ as mass and the application of a simultaneous measurement technique to the H2+/D+ cyclotron frequency ratio, yielding a deuteron/proton mass ratio at 5 × 10−12; new measurements of HD+/3He+, HD+/T+, and T+/3He+ leading to a tritium beta-decay Q-value with an uncertainty of 22 meV, and atomic masses of the helion and triton at 13 × 10−12; and a new measurement of the mass of the alpha-particle against 12C at 12 × 10−12. Some of these results are in strong disagreement with previous values in the literature. Their impact in determining a precise proton/electron mass ratio and electron atomic mass from spectroscopy of the HD+ molecular ion is also discussed.
{"title":"Progress in High-Precision Mass Measurements of Light Ions","authors":"Edmund G. Myers","doi":"10.3390/atoms12020008","DOIUrl":"https://doi.org/10.3390/atoms12020008","url":null,"abstract":"Significant advances in Penning trap measurements of atomic masses and mass ratios of the proton, deuteron, triton, helion, and alpha-particle have occurred in the last five years. These include a measurement of the mass of the deuteron against 12C with 8.5 × 10−12 fractional uncertainty; resolution of vibrational levels of H2+ as mass and the application of a simultaneous measurement technique to the H2+/D+ cyclotron frequency ratio, yielding a deuteron/proton mass ratio at 5 × 10−12; new measurements of HD+/3He+, HD+/T+, and T+/3He+ leading to a tritium beta-decay Q-value with an uncertainty of 22 meV, and atomic masses of the helion and triton at 13 × 10−12; and a new measurement of the mass of the alpha-particle against 12C at 12 × 10−12. Some of these results are in strong disagreement with previous values in the literature. Their impact in determining a precise proton/electron mass ratio and electron atomic mass from spectroscopy of the HD+ molecular ion is also discussed.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140493153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nilanjan Mukherjee, Abhijit Bhattacharyya, K. Chakrabarti
We report here an R-matrix study of electron collision with the BeO+ molecular ion in its X 2Π ground state and at a single bond length, namely its equilibrium Re=2.7023 a0. Firstly, a good quality configuration interaction calculation is performed for the BeO+ ground and excited states. We then perform scattering calculations using the R-matrix method to yield the cross-section for electronic excitation to several of its excited states. The electron impact dissociation of BeO+ through the two lowest dissociation channels, namely the Be+(2Sg) + O(3Pg) and Be+(2Sg) + O(1Dg) dissociation channels, is estimated using the electronic excitation cross-sections. Rotational excitation cross-sections are provided for the j(=0)→j′(=1,2,3) rotational transitions. Our calculations also yield e + BeO+ neutral Feshbach resonances and their widths which we present systematically categorized by their symmetry and quantum defects, and BeO-bound Rydberg states at the BeO+ equilibrium. The full potential energy curves for the resonant states, their widths and the bound Rydberg states, whose details we propose to give in a subsequent work, can be the starting point of other collision calculations.
我们在此报告了在 X 2Π 基态和单一键长（即平衡 Re=2.7023 a0）下电子与 BeO+ 分子离子碰撞的 R 矩阵研究。首先，我们对 BeO+ 的基态和激发态进行了高质量的构型相互作用计算。然后，我们使用 R 矩阵方法进行散射计算，得出了电子激发到几个激发态的截面。利用电子激发截面估算了 BeO+ 通过两个最低解离通道（即 Be+(2Sg) + O(3Pg) 和 Be+(2Sg) + O(1Dg) 解离通道）的电子撞击解离情况。我们还提供了 j(=0)→j′(=1,2,3)旋转跃迁的旋转激发截面。我们的计算还得出了 e + BeO+ 中性费什巴赫共振及其宽度，并根据其对称性和量子缺陷以及 BeO+ 平衡时的 BeO 结合雷德贝格态进行了系统分类。共振态的完整势能曲线、它们的宽度和束缚雷德贝格态的细节我们将在后续工作中给出，它们可以作为其他碰撞计算的起点。
{"title":"R-Matrix Calculation of Electron Collision with the BeO+ Molecular Ion","authors":"Nilanjan Mukherjee, Abhijit Bhattacharyya, K. Chakrabarti","doi":"10.3390/atoms12010002","DOIUrl":"https://doi.org/10.3390/atoms12010002","url":null,"abstract":"We report here an R-matrix study of electron collision with the BeO+ molecular ion in its X 2Π ground state and at a single bond length, namely its equilibrium Re=2.7023 a0. Firstly, a good quality configuration interaction calculation is performed for the BeO+ ground and excited states. We then perform scattering calculations using the R-matrix method to yield the cross-section for electronic excitation to several of its excited states. The electron impact dissociation of BeO+ through the two lowest dissociation channels, namely the Be+(2Sg) + O(3Pg) and Be+(2Sg) + O(1Dg) dissociation channels, is estimated using the electronic excitation cross-sections. Rotational excitation cross-sections are provided for the j(=0)→j′(=1,2,3) rotational transitions. Our calculations also yield e + BeO+ neutral Feshbach resonances and their widths which we present systematically categorized by their symmetry and quantum defects, and BeO-bound Rydberg states at the BeO+ equilibrium. The full potential energy curves for the resonant states, their widths and the bound Rydberg states, whose details we propose to give in a subsequent work, can be the starting point of other collision calculations.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139440024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extreme learning machines explore nonlinear random projections to perform computing tasks on high-dimensional output spaces. Since training only occurs at the output layer, the approach has the potential to speed up the training process and the capacity to turn any physical system into a computing platform. Yet, requiring strong nonlinear dynamics, optical solutions operating at fast processing rates and low power can be hard to achieve with conventional nonlinear optical materials. In this context, this manuscript explores the possibility of using atomic gases in near-resonant conditions to implement an optical extreme learning machine leveraging their enhanced nonlinear optical properties. Our results suggest that these systems have the potential not only to work as an optical extreme learning machine but also to perform these computations at the few-photon level, paving opportunities for energy-efficient computing solutions.
{"title":"Optical Extreme Learning Machines with Atomic Vapors","authors":"Nuno A Silva, Vicente Rocha, Tiago D. Ferreira","doi":"10.3390/atoms12020010","DOIUrl":"https://doi.org/10.3390/atoms12020010","url":null,"abstract":"Extreme learning machines explore nonlinear random projections to perform computing tasks on high-dimensional output spaces. Since training only occurs at the output layer, the approach has the potential to speed up the training process and the capacity to turn any physical system into a computing platform. Yet, requiring strong nonlinear dynamics, optical solutions operating at fast processing rates and low power can be hard to achieve with conventional nonlinear optical materials. In this context, this manuscript explores the possibility of using atomic gases in near-resonant conditions to implement an optical extreme learning machine leveraging their enhanced nonlinear optical properties. Our results suggest that these systems have the potential not only to work as an optical extreme learning machine but also to perform these computations at the few-photon level, paving opportunities for energy-efficient computing solutions.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140512646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Motoshi Goto, G. Motojima, Ryuichi Sakamoto, Bernard Pégourié, Akinobu Matsuyama, Tetsutarou Oishi, T. Kawate, Yasuko Kawamoto
We have recently incorporated the occupation probability formalism (OPF) in the simulation model [C. Stehlé and S. Jacquemot, Astron. Astrophys. 271, 348 (1993)] to have a smooth transition from discrete lines to continuum spectrum in the wavelength range near the Balmer series limit. We have analyzed spectra measured for the hydrogen pellet ablation cloud in the Large Helical Device with the revised model, and have found that the electron density in the ablation cloud has a close correlation with the electron temperature of the background plasma. This type of correlation is first confirmed in the present analysis and should give a new insight in the simulation studies of pellet ablation for the magnetically confined fusion plasma.
我们最近在模拟模型中加入了占位概率形式主义（OPF）[C. Stehlé 和 S. Jacquemot，Astron. Astrophys.我们利用修订后的模型分析了在大型螺旋装置中氢丸烧蚀云测得的光谱，发现烧蚀云中的电子密度与背景等离子体的电子温度密切相关。这种相关性在本次分析中首次得到了证实，并为磁约束聚变等离子体的颗粒烧蚀模拟研究提供了新的视角。
{"title":"Better Understanding of Hydrogen Pellet Ablation Cloud Spectra through the Occupation Probability Formalism in LHD","authors":"Motoshi Goto, G. Motojima, Ryuichi Sakamoto, Bernard Pégourié, Akinobu Matsuyama, Tetsutarou Oishi, T. Kawate, Yasuko Kawamoto","doi":"10.3390/atoms12010001","DOIUrl":"https://doi.org/10.3390/atoms12010001","url":null,"abstract":"We have recently incorporated the occupation probability formalism (OPF) in the simulation model [C. Stehlé and S. Jacquemot, Astron. Astrophys. 271, 348 (1993)] to have a smooth transition from discrete lines to continuum spectrum in the wavelength range near the Balmer series limit. We have analyzed spectra measured for the hydrogen pellet ablation cloud in the Large Helical Device with the revised model, and have found that the electron density in the ablation cloud has a close correlation with the electron temperature of the background plasma. This type of correlation is first confirmed in the present analysis and should give a new insight in the simulation studies of pellet ablation for the magnetically confined fusion plasma.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139447593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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