Pub Date : 2024-08-30DOI: 10.1088/1361-6455/ad717d
A del Rio-Lima, F J Poveda-Cuevas, O Castaños
The dynamics of an atom of three levels in Λ configuration interacting with a quantized field of two modes in a cavity is studied within the rotating wave approximation by considering experimental values of accessible hyperfine levels of alkali atoms. The Hamiltonian model is constructed on the basis of the direct product of the atomic states with Fock states of light. This simplified basis allows us to generalize the state of light to any quantum field. The interaction term of the Hamiltonian restricts the system to a 3D Hilbert space. The system’s time evolution results show some similarities with the effective two-level system, such as the presence of collapses and revivals and the atom-field entanglement. By an analysis of the statistics of the photons, we show that when the three-level atom is interacting with a coherent field of two modes, it is possible to control experimentally the statistics of the field to be super-Poissonian or sub-Poissonian by the choice of the initial atomic state.
{"title":"Entanglement of a three-level atom interacting with two-modes field in a cavity","authors":"A del Rio-Lima, F J Poveda-Cuevas, O Castaños","doi":"10.1088/1361-6455/ad717d","DOIUrl":"https://doi.org/10.1088/1361-6455/ad717d","url":null,"abstract":"The dynamics of an atom of three levels in Λ configuration interacting with a quantized field of two modes in a cavity is studied within the rotating wave approximation by considering experimental values of accessible hyperfine levels of alkali atoms. The Hamiltonian model is constructed on the basis of the direct product of the atomic states with Fock states of light. This simplified basis allows us to generalize the state of light to any quantum field. The interaction term of the Hamiltonian restricts the system to a 3D Hilbert space. The system’s time evolution results show some similarities with the effective two-level system, such as the presence of collapses and revivals and the atom-field entanglement. By an analysis of the statistics of the photons, we show that when the three-level atom is interacting with a coherent field of two modes, it is possible to control experimentally the statistics of the field to be super-Poissonian or sub-Poissonian by the choice of the initial atomic state.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"121 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-29DOI: 10.1088/1361-6455/ad717c
Samim Akhtar, Aparajita Das, Md Mabud Hossain
In this article, we present the influence of structured light on the line shape of closed hyperfine transition F=2→F′=3 of 87Rb-D2 line by monitoring the linearly polarized probe Gaussian beam in the presence of circularly polarized pump Laguerre–Gaussian (LG) beam having different orders of orbital angular momentum (OAM). It is observed that both the amplitude and line-width of the closed hyperfine signal under polarization spectroscopy (PS) are enhanced (reduced) with the increasing values of the pump light ellipticity for the non-zero-order (zero-order) OAM. Furthermore, the dispersion-like PS signal of the closed hyperfine transition is modified by varying the pump power and angular mismatch of the pump-probe beams. The experimental results demonstrate that the anisotropy of an atomic medium can be influenced by the OAM of light and can be further modulated by tuning the ellipticity of the structured light.
{"title":"Polarization spectroscopy of 87Rb-D2 line using structured light: controlling the line shape of closed hyperfine transition","authors":"Samim Akhtar, Aparajita Das, Md Mabud Hossain","doi":"10.1088/1361-6455/ad717c","DOIUrl":"https://doi.org/10.1088/1361-6455/ad717c","url":null,"abstract":"In this article, we present the influence of structured light on the line shape of closed hyperfine transition <inline-formula>\u0000<tex-math><?CDATA $F = 2 rightarrow F^{^{prime}} = 3$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>F</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn><mml:mo stretchy=\"false\">→</mml:mo><mml:msup><mml:mi>F</mml:mi><mml:mrow><mml:mi>′</mml:mi></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"bad717cieqn1.gif\"></inline-graphic></inline-formula> of <sup>87</sup>Rb-D<sub>2</sub> line by monitoring the linearly polarized probe Gaussian beam in the presence of circularly polarized pump Laguerre–Gaussian (LG) beam having different orders of orbital angular momentum (OAM). It is observed that both the amplitude and line-width of the closed hyperfine signal under polarization spectroscopy (PS) are enhanced (reduced) with the increasing values of the pump light ellipticity for the non-zero-order (zero-order) OAM. Furthermore, the dispersion-like PS signal of the closed hyperfine transition is modified by varying the pump power and angular mismatch of the pump-probe beams. The experimental results demonstrate that the anisotropy of an atomic medium can be influenced by the OAM of light and can be further modulated by tuning the ellipticity of the structured light.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"9 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-29DOI: 10.1088/1361-6455/ad717f
Danny Fainozzi, Riccardo Cucini, Joan Vila-Comamala, Frederico Lima, Fernando Ardana-Lamas, Luis Bañares, Matias Bargheer, Filippo Bencivenga, Nadia Berndt, Martin Beye, Mykola Biednov, Stefano Bonetti, Marta Brioschi, Andrea Cannizzo, Pietro Carrara, Majed Chergui, Christian David, Robin Y Engel, Eugenio Ferrari, Thomas Feurer, Paul Frankenberger, Wojciech M Gawelda, Alessandro Gessini, Siti Heder, Xinchao Huang, Nupur N Khatu, Martin Knoll, Anders Madsen, Talgat Mamyrbayev, Claudio Masciovecchio, Alexei A Maznev, Christopher Milne, Riccardo Mincigrucci, Keith A Nelson, Ettore Paltanin, Giorgio Rossi, Markus Scholz, Carles Serrat, Urs Staub, Jakub Szlachetko, Renato Torre, Mano R Dhanalakshmi-Veeraraj, Han Xu, Peter Zalden, Cristian Svetina
Transient grating spectroscopy is a specialized application of the four-wave-mixing methodology and constitutes a versatile technique for investigating the dynamics of vibrational, magnetic and electronic degrees of freedom of matter in a background-free fashion. Recent developments in free-electron laser sources have enabled the extension of this technique into the extreme ultraviolet range. Ongoing efforts to expand transient grating spectroscopy into the x-ray regime promise numerous advantages: (1) substantial penetration depths that allow for probing bulk material properties, (2) element specificity via specific core-excited states, and (3) short wavelengths that allow for excitation gratings with higher momentum transfer and improved spatial resolution. In this study, we comprehensively outline the procedures for conducting x-ray transient grating pump/optical probe experiment. The process encompasses the design and alignment of the experimental setup, as well as the subsequent steps involved in data acquisition and analysis. This paper is intended as a comprehensive guide for researchers interested in implementing x-ray transient grating spectroscopy, providing valuable insights into the intricacies of the experimental workflow required for this novel technique. Furthermore, we discuss the potential for extending this methodology to an x-ray pump/x-ray probe scheme, envisioning a future direction that holds promise for enhancing the capabilities and scope of x-ray transient grating spectroscopy, opening new opportunities for studying ultrafast processes with unprecedented temporal and spatial resolutions.
瞬态光栅光谱学是四波混频方法的一种专门应用，是一种以无背景方式研究物质振动、磁性和电子自由度动态的多功能技术。自由电子激光源的最新发展使这项技术得以扩展到极紫外范围。目前正在进行的将瞬态光栅光谱技术扩展到 X 射线领域的工作具有诸多优势：（1）穿透深度大，可探测大块材料特性；（2）通过特定的核心激发态实现元素特异性；（3）波长短，可实现具有更高动量传递和更高空间分辨率的激发光栅。在本研究中，我们全面概述了进行 X 射线瞬态光栅泵浦/光学探针实验的程序。该过程包括实验装置的设计和调整，以及随后的数据采集和分析步骤。本文旨在为有兴趣实施 X 射线瞬态光栅光谱学的研究人员提供全面指导，让他们深入了解这项新技术所需的错综复杂的实验工作流程。此外，我们还讨论了将这一方法扩展到 X 射线泵/X 射线探针方案的可能性，展望了有望增强 X 射线瞬态光栅光谱学的能力和范围的未来方向，为以前所未有的时间和空间分辨率研究超快过程提供了新的机遇。
{"title":"Protocols for x-ray transient grating pump/optical probe experiments at x-ray free electron lasers","authors":"Danny Fainozzi, Riccardo Cucini, Joan Vila-Comamala, Frederico Lima, Fernando Ardana-Lamas, Luis Bañares, Matias Bargheer, Filippo Bencivenga, Nadia Berndt, Martin Beye, Mykola Biednov, Stefano Bonetti, Marta Brioschi, Andrea Cannizzo, Pietro Carrara, Majed Chergui, Christian David, Robin Y Engel, Eugenio Ferrari, Thomas Feurer, Paul Frankenberger, Wojciech M Gawelda, Alessandro Gessini, Siti Heder, Xinchao Huang, Nupur N Khatu, Martin Knoll, Anders Madsen, Talgat Mamyrbayev, Claudio Masciovecchio, Alexei A Maznev, Christopher Milne, Riccardo Mincigrucci, Keith A Nelson, Ettore Paltanin, Giorgio Rossi, Markus Scholz, Carles Serrat, Urs Staub, Jakub Szlachetko, Renato Torre, Mano R Dhanalakshmi-Veeraraj, Han Xu, Peter Zalden, Cristian Svetina","doi":"10.1088/1361-6455/ad717f","DOIUrl":"https://doi.org/10.1088/1361-6455/ad717f","url":null,"abstract":"Transient grating spectroscopy is a specialized application of the four-wave-mixing methodology and constitutes a versatile technique for investigating the dynamics of vibrational, magnetic and electronic degrees of freedom of matter in a background-free fashion. Recent developments in free-electron laser sources have enabled the extension of this technique into the extreme ultraviolet range. Ongoing efforts to expand transient grating spectroscopy into the x-ray regime promise numerous advantages: (1) substantial penetration depths that allow for probing bulk material properties, (2) element specificity via specific core-excited states, and (3) short wavelengths that allow for excitation gratings with higher momentum transfer and improved spatial resolution. In this study, we comprehensively outline the procedures for conducting x-ray transient grating pump/optical probe experiment. The process encompasses the design and alignment of the experimental setup, as well as the subsequent steps involved in data acquisition and analysis. This paper is intended as a comprehensive guide for researchers interested in implementing x-ray transient grating spectroscopy, providing valuable insights into the intricacies of the experimental workflow required for this novel technique. Furthermore, we discuss the potential for extending this methodology to an x-ray pump/x-ray probe scheme, envisioning a future direction that holds promise for enhancing the capabilities and scope of x-ray transient grating spectroscopy, opening new opportunities for studying ultrafast processes with unprecedented temporal and spatial resolutions.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"13 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-29DOI: 10.1088/1361-6455/ad717e
Ziyad Imara, Khadija El Anouz, Abderrahim El Allati
We present a model for investigating the entanglement features of four magnon modes in four yttrium-iron-garnet spheres dispersed in two microwave cavities (each cavity containing two spheres), which are driven by a squeezed field under actual experimental conditions. Each two-magnon mode inside each cavity is coupled via a beam splitter. We solve the covariance matrix associated with the four magnons, taking into account the relevant physical parameters. To quantify the degree of entanglement, we use the logarithmic negativity measure. Our study focuses on two parts. First, we study the entanglement properties between magnon modes by modifying the system parameters, and comparing the results with those obtained when we use a single magnon in each cavity, i.e. when one of the two magnons is not coupled to the cavity. In the second part, we give a new method for enhancing and controlling entanglement between magnon modes. We analyze the case where one of the two magnons is not coupled to the cavity, which can result a significant entanglement. Indeed, this goal is met in our situation by including an effective magnon–magnon coupling into both cavities. However, at high temperatures, the entanglement is almost completely broken. It can withstand temperatures of up to hundreds of millikelvin when using an experimentally accessible two-mode squeezed source.
{"title":"Engineering and control of the entanglement for four Magnon modes inside two microwave cavities","authors":"Ziyad Imara, Khadija El Anouz, Abderrahim El Allati","doi":"10.1088/1361-6455/ad717e","DOIUrl":"https://doi.org/10.1088/1361-6455/ad717e","url":null,"abstract":"We present a model for investigating the entanglement features of four magnon modes in four yttrium-iron-garnet spheres dispersed in two microwave cavities (each cavity containing two spheres), which are driven by a squeezed field under actual experimental conditions. Each two-magnon mode inside each cavity is coupled via a beam splitter. We solve the covariance matrix associated with the four magnons, taking into account the relevant physical parameters. To quantify the degree of entanglement, we use the logarithmic negativity measure. Our study focuses on two parts. First, we study the entanglement properties between magnon modes by modifying the system parameters, and comparing the results with those obtained when we use a single magnon in each cavity, i.e. when one of the two magnons is not coupled to the cavity. In the second part, we give a new method for enhancing and controlling entanglement between magnon modes. We analyze the case where one of the two magnons is not coupled to the cavity, which can result a significant entanglement. Indeed, this goal is met in our situation by including an effective magnon–magnon coupling into both cavities. However, at high temperatures, the entanglement is almost completely broken. It can withstand temperatures of up to hundreds of millikelvin when using an experimentally accessible two-mode squeezed source.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"3 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-27DOI: 10.1088/1361-6455/ad6b68
Moses Simon, Prashant Chauhan
This communication proposes an analytical model to investigate the nanoparticle-based nonlinear absorption phenomenon associated with an obliquely incident p-polarized laser beam on a metallic surface. In this scheme, the surface is ingrained with noble-metal spherical nanoparticles and cylindrical nanoparticles in the presence of an external static magnetic field. The absorption of laser energy in the presence of nanoparticles (NPs) is attributed to surface plasmon resonance and enhanced magnetic-field effects. The absorption phenomenon is significantly enhanced by the incorporation of nanostructures and a magnetic field. The ellipticity characterizing parameter, which significantly influences the resonant frequency of different nanometric structures, has also been analysed and discussed. The effects of varying the magnetic field intensity, incident angle, size, and spacing of the NP were examined to determine their influence on the anomalous absorption of the laser. Furthermore, a direct dependency was found between the absorption coefficient and transmission coefficient of the incident laser, as well as the dimensions of the NPs. Several applications have direct relevance to this study, including biosensors such as DNA sensors and immunosensors, photothermal therapy, photoacoustic imaging, optoelectronic devices, solar cells, and surface-enhanced Raman spectroscopy.
这篇论文提出了一个分析模型，用于研究与斜入射p偏振激光束在金属表面上相关的基于纳米粒子的非线性吸收现象。在这一方案中，表面在外部静磁场的作用下嵌入了贵金属球形纳米粒子和圆柱形纳米粒子。纳米粒子（NPs）对激光能量的吸收归因于表面等离子体共振和增强的磁场效应。加入纳米结构和磁场后，吸收现象明显增强。椭圆度表征参数对不同纳米结构的共振频率有显著影响，我们也对该参数进行了分析和讨论。研究了改变磁场强度、入射角度、尺寸和纳米粒子间距的效果，以确定它们对激光反常吸收的影响。此外，还发现入射激光的吸收系数和透射系数与 NPs 的尺寸有直接关系。与这项研究直接相关的应用包括 DNA 传感器和免疫传感器等生物传感器、光热疗法、光声成像、光电器件、太阳能电池和表面增强拉曼光谱。
{"title":"Magnetic field enhanced laser absorption on a metallic surface incorporated with shape-dependent nanostructures","authors":"Moses Simon, Prashant Chauhan","doi":"10.1088/1361-6455/ad6b68","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b68","url":null,"abstract":"This communication proposes an analytical model to investigate the nanoparticle-based nonlinear absorption phenomenon associated with an obliquely incident p-polarized laser beam on a metallic surface. In this scheme, the surface is ingrained with noble-metal spherical nanoparticles and cylindrical nanoparticles in the presence of an external static magnetic field. The absorption of laser energy in the presence of nanoparticles (NPs) is attributed to surface plasmon resonance and enhanced magnetic-field effects. The absorption phenomenon is significantly enhanced by the incorporation of nanostructures and a magnetic field. The ellipticity characterizing parameter, which significantly influences the resonant frequency of different nanometric structures, has also been analysed and discussed. The effects of varying the magnetic field intensity, incident angle, size, and spacing of the NP were examined to determine their influence on the anomalous absorption of the laser. Furthermore, a direct dependency was found between the absorption coefficient and transmission coefficient of the incident laser, as well as the dimensions of the NPs. Several applications have direct relevance to this study, including biosensors such as DNA sensors and immunosensors, photothermal therapy, photoacoustic imaging, optoelectronic devices, solar cells, and surface-enhanced Raman spectroscopy.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"68 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-21DOI: 10.1088/1361-6455/ad6b64
A Jacob, C Müller, A B Voitkiv
We explore a mechanism for ionization in high-velocity (but not yet relativistic) collisions of light atomic particles, one of which being initially in an excited internal state. This mechanism is driven by the generalized Breit interaction and proceeds via radiative energy transport between the colliding particles which has an extremely long range. A comparison of this mechanism with those which are ‘standard’ for high-velocity collisions shows that it can play a noticeable role in collisions with excited target atoms.
{"title":"Ionization by radiative energy transport vs. impact ionization in energetic atomic collisions","authors":"A Jacob, C Müller, A B Voitkiv","doi":"10.1088/1361-6455/ad6b64","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b64","url":null,"abstract":"We explore a mechanism for ionization in high-velocity (but not yet relativistic) collisions of light atomic particles, one of which being initially in an excited internal state. This mechanism is driven by the generalized Breit interaction and proceeds via radiative energy transport between the colliding particles which has an extremely long range. A comparison of this mechanism with those which are ‘standard’ for high-velocity collisions shows that it can play a noticeable role in collisions with excited target atoms.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"79 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-14DOI: 10.1088/1361-6455/ad6b67
Zilei Yu, Xiaofang Zhao, Shuying Wang, Chu Qin, Yifan Shen, Kang Dai
Using high-resolution transient laser spectroscopy, the rotational energy transfer between LiH (12, 8) and Ar through collisions was studied. LiH (12, 8) was generated via degenerate stimulated hyper-Raman scattering. The population of LiH (12, J″ ≠ 8) generated during collisions were obtained using transient laser-induced fluorescence. According to the rate equation, the rate coefficients for the transfer from (12, 8) to (12, J″) states are between 7.1 × 10−12 and 3.5 × 10−13 cm3 molecule−1 s−1 within 2 μs of the collision occurring. Above 2 μs, the rate coefficient is no longer constant. Meanwhile, no vibrational relaxation occurs before 10 μs. The rotational energy Erot is the sum of the rotational energies of rotational states (12, J″). Within the period of 0–10 μs, the value of Erot decreases from 541 cm−1 to 390 cm−1. The distribution of translational energy Etrans at different delay time of LiH (12, 8) is obtained by measuring the Doppler broadened line widths. It increases from 707 cm−1 at 0 μs to 852 cm−1 at 10 μs. Therefore, when rotational relaxation occurs, the decrease in rotational energy is approximately equal to the increase in translational energy.
{"title":"Experimental study on rotational energy transfer in LiH (X1 ∑+ v) + Ar collisions","authors":"Zilei Yu, Xiaofang Zhao, Shuying Wang, Chu Qin, Yifan Shen, Kang Dai","doi":"10.1088/1361-6455/ad6b67","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b67","url":null,"abstract":"Using high-resolution transient laser spectroscopy, the rotational energy transfer between LiH (12, 8) and Ar through collisions was studied. LiH (12, 8) was generated via degenerate stimulated hyper-Raman scattering. The population of LiH (12, <italic toggle=\"yes\">J″</italic> ≠ 8) generated during collisions were obtained using transient laser-induced fluorescence. According to the rate equation, the rate coefficients for the transfer from (12, 8) to (12, <italic toggle=\"yes\">J″</italic>) states are between 7.1 × 10<sup>−12</sup> and 3.5 × 10<sup>−13</sup> cm<sup>3</sup> molecule<sup>−1</sup> s<sup>−1</sup> within 2 <italic toggle=\"yes\">μ</italic>s of the collision occurring. Above 2 <italic toggle=\"yes\">μ</italic>s, the rate coefficient is no longer constant. Meanwhile, no vibrational relaxation occurs before 10 <italic toggle=\"yes\">μ</italic>s. The rotational energy <italic toggle=\"yes\">E</italic><sub>rot</sub> is the sum of the rotational energies of rotational states (12, <italic toggle=\"yes\">J″</italic>). Within the period of 0–10 <italic toggle=\"yes\">μ</italic>s, the value of <italic toggle=\"yes\">E</italic><sub>rot</sub> decreases from 541 cm<sup>−1</sup> to 390 cm<sup>−1</sup>. The distribution of translational energy <italic toggle=\"yes\">E</italic><sub>trans</sub> at different delay time of LiH (12, 8) is obtained by measuring the Doppler broadened line widths. It increases from 707 cm<sup>−1</sup> at 0 <italic toggle=\"yes\">μ</italic>s to 852 cm<sup>−1</sup> at 10 <italic toggle=\"yes\">μ</italic>s. Therefore, when rotational relaxation occurs, the decrease in rotational energy is approximately equal to the increase in translational energy.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"68 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-13DOI: 10.1088/1361-6455/ad6b65
Paulo E Ibañez-Almaguer, Germán Rojas-Lorenzo, Maykel Márquez-Mijares, Jesús Rubayo-Soneira, Gennady B Sushko, Andrei V Korol, Andrey V Solov’yov
A comprehensive numerical investigation has been conducted on the angular distribution and spectrum of radiation emitted by 855 MeV electron and positron beams while traversing a ‘quasi-mosaic’ bent silicon (111) crystal. This interaction of charged particles with a bent crystal gives rise to various phenomena such as channeling, dechanneling, volume reflection, and volume capture. The crystal’s geometry, emittance of the collimated particle beams, as well as their alignment with respect to the crystal, have been taken into account as they are essential for an accurate quantitative description of the processes. The simulations have been performed using a specialized relativistic molecular dynamics module implemented in the MBN Explorer package. The angular distribution of the particles after traversing the crystal has been calculated for beams of different emittances as well as for different anticlastic curvatures of the bent crystals. For the electron beam, the angular distributions of the deflected particles and the spectrum of radiation obtained in the simulations are compared with the experimental data collected at the Mainz Microtron facility. For the positron beam such calculations have been performed for the first time. We predict significant differences in the angular distributions and the radiation spectra for positrons versus electrons.
我们对 855 兆电子伏电子束和正电子束穿过 "准马赛克 "弯曲硅 (111) 晶体时发出的辐射的角度分布和光谱进行了全面的数值研究。带电粒子与弯曲晶体的相互作用会产生各种现象，如通道、去通道、体积反射和体积捕获。晶体的几何形状、准直粒子束的发射率以及它们相对于晶体的排列方式都被考虑在内，因为它们对于准确定量地描述这些过程至关重要。模拟是使用 MBN Explorer 软件包中专门的相对论分子动力学模块进行的。针对不同发射率的光束以及弯曲晶体的不同反弹性曲率，计算了粒子穿过晶体后的角度分布。对于电子束，模拟得到的偏转粒子的角度分布和辐射光谱与在美因茨微创设备上收集到的实验数据进行了比较。对于正电子束，我们首次进行了此类计算。我们预测正电子与电子的角度分布和辐射光谱存在明显差异。
{"title":"Simulation of deflection and photon emission of ultra-relativistic electrons and positrons in a quasi-mosaic bent silicon crystal","authors":"Paulo E Ibañez-Almaguer, Germán Rojas-Lorenzo, Maykel Márquez-Mijares, Jesús Rubayo-Soneira, Gennady B Sushko, Andrei V Korol, Andrey V Solov’yov","doi":"10.1088/1361-6455/ad6b65","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b65","url":null,"abstract":"A comprehensive numerical investigation has been conducted on the angular distribution and spectrum of radiation emitted by 855 MeV electron and positron beams while traversing a ‘quasi-mosaic’ bent silicon (111) crystal. This interaction of charged particles with a bent crystal gives rise to various phenomena such as channeling, dechanneling, volume reflection, and volume capture. The crystal’s geometry, emittance of the collimated particle beams, as well as their alignment with respect to the crystal, have been taken into account as they are essential for an accurate quantitative description of the processes. The simulations have been performed using a specialized relativistic molecular dynamics module implemented in the MBN Explorer package. The angular distribution of the particles after traversing the crystal has been calculated for beams of different emittances as well as for different anticlastic curvatures of the bent crystals. For the electron beam, the angular distributions of the deflected particles and the spectrum of radiation obtained in the simulations are compared with the experimental data collected at the Mainz Microtron facility. For the positron beam such calculations have been performed for the first time. We predict significant differences in the angular distributions and the radiation spectra for positrons versus electrons.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"3 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-13DOI: 10.1088/1361-6455/ad6b66
Junbo Liu, Xiangjun Lai, Xiao Hu Ji, Aihua Liu, Henry E Montgomery Jr, Yew Kam Ho, Li Guang Jiao
The multipole (dipole, quadrupole, and octopole) photon-absorption transition oscillator strengths for the ground state of hydrogen atom confined in Gaussian potential are investigated for a great variety of potential depths and confining radii. It is interestingly found that at fixed potential depth the gradual increase of confining radius shows first destructive and then constructive effect on the multipole oscillator strengths. Such an effect can be understood from the overlap between the initial and final states. Multipole polarizabilities of the system are obtained through the sum-over-states formalism where the contributions from both the bound and continuum spectra of the system are included. Although the separate bound and continuum contributions can not be determined accurately, due to the long-range nature of the Coulomb potential introduced by the nucleus, their summations can be obtained to reasonably good accuracy, leading to fast convergence of numerical calculations of multipole polarizabilities. The present results are compared with previous calculations available in the literature. Although good agreement is observed for the dipole polarizability, significant differences exist in the quadrupole polarizability and orders-of-magnitude differences appear in the octopole polarizability. The possible reason for such large differences is analyzed by comparing the sum rule of corresponding oscillator strengths.
{"title":"A comparative study of transition oscillator strengths and static polarizabilities of the hydrogen atom confined in Gaussian potential","authors":"Junbo Liu, Xiangjun Lai, Xiao Hu Ji, Aihua Liu, Henry E Montgomery Jr, Yew Kam Ho, Li Guang Jiao","doi":"10.1088/1361-6455/ad6b66","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b66","url":null,"abstract":"The multipole (dipole, quadrupole, and octopole) photon-absorption transition oscillator strengths for the ground state of hydrogen atom confined in Gaussian potential are investigated for a great variety of potential depths and confining radii. It is interestingly found that at fixed potential depth the gradual increase of confining radius shows first destructive and then constructive effect on the multipole oscillator strengths. Such an effect can be understood from the overlap between the initial and final states. Multipole polarizabilities of the system are obtained through the sum-over-states formalism where the contributions from both the bound and continuum spectra of the system are included. Although the separate bound and continuum contributions can not be determined accurately, due to the long-range nature of the Coulomb potential introduced by the nucleus, their summations can be obtained to reasonably good accuracy, leading to fast convergence of numerical calculations of multipole polarizabilities. The present results are compared with previous calculations available in the literature. Although good agreement is observed for the dipole polarizability, significant differences exist in the quadrupole polarizability and orders-of-magnitude differences appear in the octopole polarizability. The possible reason for such large differences is analyzed by comparing the sum rule of corresponding oscillator strengths.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"78 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-13DOI: 10.1088/1361-6455/ad5fd4
Daria Popova-Gorelova
Optical manipulation of light is a highly relevant concept in modern solid-state physics and its microscopic mechanisms are widely investigated. From this perspective, we discuss how x-ray and extreme ultraviolet pulses that probe a material during the time it is driven by optical light can deliver valuable microscopic details about electron dynamics.
{"title":"Perspective: towards real-time extreme ultraviolet to x-ray imaging and spectroscopy of laser-driven materials","authors":"Daria Popova-Gorelova","doi":"10.1088/1361-6455/ad5fd4","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5fd4","url":null,"abstract":"Optical manipulation of light is a highly relevant concept in modern solid-state physics and its microscopic mechanisms are widely investigated. From this perspective, we discuss how x-ray and extreme ultraviolet pulses that probe a material during the time it is driven by optical light can deliver valuable microscopic details about electron dynamics.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"33 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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