We review our group’s most significant results concerning the collision of positrons and electrons with small molecules. Total and triple differential cross sections for the ionization of these targets were calculated in the distorted wave Born approximation using Gaussian molecular orbitals. Different models were tested. The obtained theoretical results reproduced, in most cases, the features observed in the experimental data.
{"title":"Electron and Positron Impact Ionization of Molecules","authors":"L. Nagy, I. Tóth, R. Campeanu","doi":"10.3390/atoms12080038","DOIUrl":"https://doi.org/10.3390/atoms12080038","url":null,"abstract":"We review our group’s most significant results concerning the collision of positrons and electrons with small molecules. Total and triple differential cross sections for the ionization of these targets were calculated in the distorted wave Born approximation using Gaussian molecular orbitals. Different models were tested. The obtained theoretical results reproduced, in most cases, the features observed in the experimental data.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141812654","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}
We present a classical treatment of the ionization and electron-capture processes in the interaction of protons with neutral noble-gas atoms, namely, Ne, Ar, Kr, and Xe. We used a three-body classical-trajectory Monte Carlo (CTMC) method to calculate the total (TCS) and differential (DCS) cross sections of single-electron processes. The Garvey-type model potential was employed in the CTMC model to describe the collision between the projectile and the target, accounting for the screening effect of the inactive electrons. The TCSs are evaluated for impact energies in the energy range between 0.2 keV and 50 MeV for a number of sub-shells of the targets. The ionization DCS are evaluated for an impact energy of 35 keV, focusing on the outer sub-shells only. We found that our ionization and electron-capture TCSs are in very good agreement with the previous theoretical and experimental data for all targets. Moreover, we presented single (SDCS)- and double (DDCS)-differential cross sections as a function of the energy and ejection angle of the ionized electron for all collision systems.
{"title":"Interaction of Protons with Noble-Gas Atoms: Total and Differential Cross Sections","authors":"M. Al-Ajaleen, K. Tőkési","doi":"10.3390/atoms12050028","DOIUrl":"https://doi.org/10.3390/atoms12050028","url":null,"abstract":"We present a classical treatment of the ionization and electron-capture processes in the interaction of protons with neutral noble-gas atoms, namely, Ne, Ar, Kr, and Xe. We used a three-body classical-trajectory Monte Carlo (CTMC) method to calculate the total (TCS) and differential (DCS) cross sections of single-electron processes. The Garvey-type model potential was employed in the CTMC model to describe the collision between the projectile and the target, accounting for the screening effect of the inactive electrons. The TCSs are evaluated for impact energies in the energy range between 0.2 keV and 50 MeV for a number of sub-shells of the targets. The ionization DCS are evaluated for an impact energy of 35 keV, focusing on the outer sub-shells only. We found that our ionization and electron-capture TCSs are in very good agreement with the previous theoretical and experimental data for all targets. Moreover, we presented single (SDCS)- and double (DDCS)-differential cross sections as a function of the energy and ejection angle of the ionized electron for all collision systems.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141003746","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}
The Atomic and Molecular Data Unit of the International Atomic Energy Agency has developed a new database, CollisionDB, to provide an open, free, robust and long-term repository of data on plasma collisional processes. The database contains data on cross sections and rate coefficients for collisions of electrons, photons and heavy particles with atomic and molecular species. A fundamental requirement for this database is the implementation of standardized metadata, which provide an unambiguous description of the collisional data available in peer-reviewed sources. CollisionDB offers both a browser-based search interface and an application programming interface (API) that allows users to filter, process and compare collisional datasets. For this purpose, a Python package PyCollisionDB has been developed to access the CollisionDB API. Here, we present an overview of the technical developments, including data schemas, standards and user interface underlying the CollisionDB application, with particular emphasis on the API developed to support the integration of data into modeling and other codes.
{"title":"CollisionDB: A New Database of Atomic and Molecular Collisional Processes with an Interactive API","authors":"C. Hill, Dipti, K. Heinola, Martin Hanicinec","doi":"10.3390/atoms12040020","DOIUrl":"https://doi.org/10.3390/atoms12040020","url":null,"abstract":"The Atomic and Molecular Data Unit of the International Atomic Energy Agency has developed a new database, CollisionDB, to provide an open, free, robust and long-term repository of data on plasma collisional processes. The database contains data on cross sections and rate coefficients for collisions of electrons, photons and heavy particles with atomic and molecular species. A fundamental requirement for this database is the implementation of standardized metadata, which provide an unambiguous description of the collisional data available in peer-reviewed sources. CollisionDB offers both a browser-based search interface and an application programming interface (API) that allows users to filter, process and compare collisional datasets. For this purpose, a Python package PyCollisionDB has been developed to access the CollisionDB API. Here, we present an overview of the technical developments, including data schemas, standards and user interface underlying the CollisionDB application, with particular emphasis on the API developed to support the integration of data into modeling and other codes.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140374883","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}
Spectral line shapes code in plasmas (SLSPs) code comparison workshops have been organized in the last decade with the aim of comparing the spectra obtained with independently developed analytical and numerical models. Here, we consider the simultaneous effect of a plasma microfield and a periodic electric field on the hydrogen lines Lyman-α, Lyman-β, Balmer-α, and Balmer-β for plasma conditions where the Stark effect usually dominates line broadening.
{"title":"Line Shape Code Comparison of the Effect of Periodic Fields on Hydrogen Lines","authors":"I. Hannachi, Spiros Alexiou, Roland J Stamm","doi":"10.3390/atoms12040019","DOIUrl":"https://doi.org/10.3390/atoms12040019","url":null,"abstract":"Spectral line shapes code in plasmas (SLSPs) code comparison workshops have been organized in the last decade with the aim of comparing the spectra obtained with independently developed analytical and numerical models. Here, we consider the simultaneous effect of a plasma microfield and a periodic electric field on the hydrogen lines Lyman-α, Lyman-β, Balmer-α, and Balmer-β for plasma conditions where the Stark effect usually dominates line broadening.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140212600","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}
The present paper discusses a number of topics relevant to line broadening in the presence of periodic oscillatory fields. Specifically, we discuss the applicablility of the expression usually employed to compute the autocorrelation function, the dressing, accounting for random phases, neglecting fine structure and numerical issues associated with stiffnes.
{"title":"General Aspects of Line Shapes in Plasmas in the Presence of External Electric Fields","authors":"Spiros Alexiou","doi":"10.3390/atoms12030017","DOIUrl":"https://doi.org/10.3390/atoms12030017","url":null,"abstract":"The present paper discusses a number of topics relevant to line broadening in the presence of periodic oscillatory fields. Specifically, we discuss the applicablility of the expression usually employed to compute the autocorrelation function, the dressing, accounting for random phases, neglecting fine structure and numerical issues associated with stiffnes.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140237722","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}
Based on the detailed term accounting approach, the relationship between extreme ultraviolet conversion efficiency and plasma conditions, which range from 5 to 200 eV for plasma temperature and from 4.63 × 1017 to 4.63 × 1022 cm−3 for plasma density, is studied for lithium plasmas through spectral simulations involving very extended atomic configurations, including a benchmark set of autoionizing states. The theoretical limit of the EUV conversion efficiency and its dependence on sustained plasma time are given for different plasma densities. The present study provides the necessary understanding of EUV formation from the perspective of atomic physics and also provides useful knowledge for improving EUV conversion efficiency with different technologies.
{"title":"Simulation of Extreme Ultraviolet Radiation and Conversion Efficiency of Lithium Plasma in a Wide Range of Plasma Situations","authors":"Xiangdong Li, F. Rosmej, Zhanbin Chen","doi":"10.3390/atoms12030016","DOIUrl":"https://doi.org/10.3390/atoms12030016","url":null,"abstract":"Based on the detailed term accounting approach, the relationship between extreme ultraviolet conversion efficiency and plasma conditions, which range from 5 to 200 eV for plasma temperature and from 4.63 × 1017 to 4.63 × 1022 cm−3 for plasma density, is studied for lithium plasmas through spectral simulations involving very extended atomic configurations, including a benchmark set of autoionizing states. The theoretical limit of the EUV conversion efficiency and its dependence on sustained plasma time are given for different plasma densities. The present study provides the necessary understanding of EUV formation from the perspective of atomic physics and also provides useful knowledge for improving EUV conversion efficiency with different technologies.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140250183","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}
G. Robb, Josh G. Walker, G. Oppo, Thorsten Ackemann
We show that a Bose–Einstein Condensate illuminated by a far off-resonant optical pump field and its retroreflection from a feedback mirror can produce stable, localised structures known as optomechanical droplets. We show that these droplets could be used to measure the acceleration of a BEC via continuous monitoring of the position of the droplet via the optical intensity distribution.
{"title":"Continuous Acceleration Sensing Using Optomechanical Droplets","authors":"G. Robb, Josh G. Walker, G. Oppo, Thorsten Ackemann","doi":"10.3390/atoms12030015","DOIUrl":"https://doi.org/10.3390/atoms12030015","url":null,"abstract":"We show that a Bose–Einstein Condensate illuminated by a far off-resonant optical pump field and its retroreflection from a feedback mirror can produce stable, localised structures known as optomechanical droplets. We show that these droplets could be used to measure the acceleration of a BEC via continuous monitoring of the position of the droplet via the optical intensity distribution.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140261063","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}
Optical lattice clocks combine the accuracy and stability required for next-generation frequency standards. At the heart of these clocks are carefully engineered optical lattices tuned to a wavelength where the differential AC Stark shift between ground and excited states vanishes—the so called ‘magic’ wavelength. To date, only alkaline-earth-like atoms utilizing clock transitions with total electronic angular momentum J=0 have successfully realized these magic wavelength optical lattices at the level necessary for state-of-the-art clock operation. In this article, we discuss two additional types of clock transitions utilizing states with J≠0, leveraging hyperfine structure to satisfy the necessary requirements for controlling lattice-induced light shifts. We propose realizing (i) clock transitions between same-parity clock states with total angular momentum F=0 and (ii) M1/E2 clock transitions between a state with F=0 and a second state with J=1/2, mF=0. We present atomic species which fulfill these requirements before giving a detailed discussion of both manganese and copper, demonstrating how these transitions provide the necessary suppression of fine structure-induced vector and tensor lattice light shifts for clock operations. Such realization of alternative optical lattice clocks promises to provide a rich variety of new atomic species for neutral atom clock operation, with applications from many-body physics to searches for new physics.
{"title":"Prospective Optical Lattice Clocks in Neutral Atoms with Hyperfine Structure","authors":"Tobias Bothwell","doi":"10.3390/atoms12030014","DOIUrl":"https://doi.org/10.3390/atoms12030014","url":null,"abstract":"Optical lattice clocks combine the accuracy and stability required for next-generation frequency standards. At the heart of these clocks are carefully engineered optical lattices tuned to a wavelength where the differential AC Stark shift between ground and excited states vanishes—the so called ‘magic’ wavelength. To date, only alkaline-earth-like atoms utilizing clock transitions with total electronic angular momentum J=0 have successfully realized these magic wavelength optical lattices at the level necessary for state-of-the-art clock operation. In this article, we discuss two additional types of clock transitions utilizing states with J≠0, leveraging hyperfine structure to satisfy the necessary requirements for controlling lattice-induced light shifts. We propose realizing (i) clock transitions between same-parity clock states with total angular momentum F=0 and (ii) M1/E2 clock transitions between a state with F=0 and a second state with J=1/2, mF=0. We present atomic species which fulfill these requirements before giving a detailed discussion of both manganese and copper, demonstrating how these transitions provide the necessary suppression of fine structure-induced vector and tensor lattice light shifts for clock operations. Such realization of alternative optical lattice clocks promises to provide a rich variety of new atomic species for neutral atom clock operation, with applications from many-body physics to searches for new physics.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140078957","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}
Previously reported atomic data (spectral lines, wavelengths, energy levels, and transition probabilities) were collected and systematically analyzed for Cs VI. The present theoretical analysis was supported by extensive calculations made for Cs VI with a pseudo-relativistic Hartree–Fock (HFR) method together with the superposition of configuration interactions implemented in Cowan’s codes. In this work, all previously reported energy levels and their (allowed) transition assignments were confirmed. A critically evaluated set of optimized energy levels with their uncertainties, observed and Ritz wavelengths along with their uncertainties, and theoretical transition probabilities with their estimated uncertainties were presented in the compilation. In addition to this, we determined the radiative transition parameters for several forbidden lines within the ground configuration 5s25p2 of Cs VI.
收集并系统分析了 Cs VI 以前报告的原子数据（光谱线、波长、能级和跃迁概率）。利用伪相对论哈特里-福克（HFR）方法和 Cowan 代码中实施的构型相互作用叠加法对 Cs VI 进行了大量计算，为本理论分析提供了支持。在这项工作中，以前报告的所有能级及其（允许的）转变分配都得到了证实。经过严格评估的优化能级及其不确定性、观测波长和里兹波长及其不确定性，以及理论转变概率及其估计不确定性都在汇编中列出。此外，我们还确定了 Cs VI 地面构型 5s25p2 内几条禁用线的辐射转变参数。
{"title":"Energy Levels and Transition Data of Cs VI","authors":"Abid Husain, Haris Kunari, Tauheed Ahmad","doi":"10.3390/atoms12030013","DOIUrl":"https://doi.org/10.3390/atoms12030013","url":null,"abstract":"Previously reported atomic data (spectral lines, wavelengths, energy levels, and transition probabilities) were collected and systematically analyzed for Cs VI. The present theoretical analysis was supported by extensive calculations made for Cs VI with a pseudo-relativistic Hartree–Fock (HFR) method together with the superposition of configuration interactions implemented in Cowan’s codes. In this work, all previously reported energy levels and their (allowed) transition assignments were confirmed. A critically evaluated set of optimized energy levels with their uncertainties, observed and Ritz wavelengths along with their uncertainties, and theoretical transition probabilities with their estimated uncertainties were presented in the compilation. In addition to this, we determined the radiative transition parameters for several forbidden lines within the ground configuration 5s25p2 of Cs VI.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140425109","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}
Atoms and ions remain in some long-lived excited levels for much longer than in typical “normal” levels, but not forever. Various cases of this so-called metastability that occur in multiply or even highly charged ions are discussed in a tutorial review, as well as examples of atomic lifetime measurements on such levels, their intentions, and some present and future applications.
{"title":"Long-Lived Levels in Multiply and Highly Charged Ions","authors":"E. Träbert","doi":"10.3390/atoms12030012","DOIUrl":"https://doi.org/10.3390/atoms12030012","url":null,"abstract":"Atoms and ions remain in some long-lived excited levels for much longer than in typical “normal” levels, but not forever. Various cases of this so-called metastability that occur in multiply or even highly charged ions are discussed in a tutorial review, as well as examples of atomic lifetime measurements on such levels, their intentions, and some present and future applications.","PeriodicalId":502621,"journal":{"name":"Atoms","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140437631","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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