Pub Date : 2025-06-04DOI: 10.1016/j.elspec.2025.147544
F. Roth , D. Potorochin , A. Gloskovskii , C. Schlueter , L. Wenthaus , S. Molodtsov , W. Drube , W. Eberhardt
This study systematically investigates core level recoil in photoemission from crystalline silicon (Si) and silicon carbide (4H-SiC), within the X-ray range of 2.45–9.5 keV. By examining the Si 2p, 2s, and C 1s core levels, we observe that SiC exhibits energy shifts exceeding single-atom recoil predictions, along with a lineshape change at higher photon energies attributed to being phonon-induced. In contrast, pure Si shows more modest shifts and line broadening, consistent with expected recoil effects. These observations imply that especially compound materials, such as SiC, exhibit an enhanced interplay of recoil and phonon dynamics, underscoring the necessity for refined photoemission models that accommodate these effects.
{"title":"Recoil effects in high energy photoemission of solids − Revisited","authors":"F. Roth , D. Potorochin , A. Gloskovskii , C. Schlueter , L. Wenthaus , S. Molodtsov , W. Drube , W. Eberhardt","doi":"10.1016/j.elspec.2025.147544","DOIUrl":"10.1016/j.elspec.2025.147544","url":null,"abstract":"<div><div>This study systematically investigates core level recoil in photoemission from crystalline silicon (Si) and silicon carbide (4H-SiC), within the X-ray range of 2.45–9.5 keV. By examining the Si 2p, 2s, and C 1s core levels, we observe that SiC exhibits energy shifts exceeding single-atom recoil predictions, along with a lineshape change at higher photon energies attributed to being phonon-induced. In contrast, pure Si shows more modest shifts and line broadening, consistent with expected recoil effects. These observations imply that especially compound materials, such as SiC, exhibit an enhanced interplay of recoil and phonon dynamics, underscoring the necessity for refined photoemission models that accommodate these effects.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"281 ","pages":"Article 147544"},"PeriodicalIF":1.8,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203726","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 : 2025-06-02DOI: 10.1016/j.elspec.2025.147542
J. Braun
Various apparative developments extended the potential of angle-resolved photoemission spectroscopy tremendously during the last decades. Modern experimental arrangements consisting of new photon sources, analyzers and detectors supply not only extremely high angle and energy resolution but also spin resolution. This provides an adequate platform to study in detail new materials like low-dimensional magnetic structures, Rashba systems, topological insulator materials or high T superconductors. The interest in such systems has grown enormously not only because of their technological relevance but even more because of exciting new physics. Furthermore, the use of photon energies from few eV up to several keV makes this experimental technique a rather unique tool to investigate the electronic properties of solids and surfaces. The following article presents a recent theoretical development in the field of angle-resolved photoemission with a special emphasis on time-resolution. In detail, a theoretical frame for two-photon photoemission spectroscopy is introduced. The approach is based on a general formulation using the Keldysh formalism for the lesser Green’s function to describe the real-time evolution of the electronic degrees of freedom in the initial state after a sufficiently weak pump pulse drives the system out of equilibrium. Assuming that not only the probe but also the pump pulse is relatively weak, a perturbative approach can be formulated that allows to compute the lesser Green function explicitly for real systems in terms of the corresponding retarded and advanced Keldysh Green functions. The final state is represented by a time-reversed low-energy electron diffraction state. This so called two-photon photoemission spectroscopy is a widely used analytical tool to study non-equilibrium phenomena in solid materials. The theoretical approach presented here aims at a material-specific, realistic and quantitative description of the time-dependent spectrum based on a picture of effectively independent electrons as described by the local-density approximation in band-structure theory.
{"title":"Relativistic theory of 2PPE","authors":"J. Braun","doi":"10.1016/j.elspec.2025.147542","DOIUrl":"10.1016/j.elspec.2025.147542","url":null,"abstract":"<div><div>Various apparative developments extended the potential of angle-resolved photoemission spectroscopy tremendously during the last decades. Modern experimental arrangements consisting of new photon sources, analyzers and detectors supply not only extremely high angle and energy resolution but also spin resolution. This provides an adequate platform to study in detail new materials like low-dimensional magnetic structures, Rashba systems, topological insulator materials or high T<span><math><msub><mrow></mrow><mrow><mi>C</mi></mrow></msub></math></span> superconductors. The interest in such systems has grown enormously not only because of their technological relevance but even more because of exciting new physics. Furthermore, the use of photon energies from few eV up to several keV makes this experimental technique a rather unique tool to investigate the electronic properties of solids and surfaces. The following article presents a recent theoretical development in the field of angle-resolved photoemission with a special emphasis on time-resolution. In detail, a theoretical frame for two-photon photoemission spectroscopy is introduced. The approach is based on a general formulation using the Keldysh formalism for the lesser Green’s function to describe the real-time evolution of the electronic degrees of freedom in the initial state after a sufficiently weak pump pulse drives the system out of equilibrium. Assuming that not only the probe but also the pump pulse is relatively weak, a perturbative approach can be formulated that allows to compute the lesser Green function explicitly for real systems in terms of the corresponding retarded and advanced Keldysh Green functions. The final state is represented by a time-reversed low-energy electron diffraction state. This so called two-photon photoemission spectroscopy is a widely used analytical tool to study non-equilibrium phenomena in solid materials. The theoretical approach presented here aims at a material-specific, realistic and quantitative description of the time-dependent spectrum based on a picture of effectively independent electrons as described by the local-density approximation in band-structure theory.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"281 ","pages":"Article 147542"},"PeriodicalIF":1.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203725","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 : 2025-05-28DOI: 10.1016/j.elspec.2025.147543
Osman Murat Ozkendir
The development of high-performance cathode materials for lithium-ion batteries (LIBs) is crucial for advancing energy storage technologies. The electronic and thermal properties of lithium cuprate (Li₂CuO₂, LCO), a promising cathode material with mixed ionic and electronic conductivity were investigated. Using a two-step computational approach, Density Functional Theory (DFT) was employ to calculate the band structure and density of states (DOS) at room temperature, revealing a direct bandgap of 1.61 eV and semiconductor-like behavior. Additionally, X-ray Absorption Fine Structure (XAFS) spectroscopy utilized to probe the temperature-dependent electronic and structural dynamics of LCO, ranging from 253 K to 473 K. The results demonstrate the stability of the Cu-O blocks under elevated temperatures, highlighting their resilience during charge-discharge cycles. The Debye-Waller factor (DWF) analysis further confirms the material's moderate thermal conductivity and structural integrity, making LCO a viable candidate for high-temperature LIB applications. This comprehensive study provides valuable insights into the electronic and thermal behavior of LCO, paving the way for the design of next-generation cathode materials with enhanced electrochemical performance and thermal stability.
{"title":"Investigating the stability and conductivity of Li₂CuO₂ for high-temperature LIB applications","authors":"Osman Murat Ozkendir","doi":"10.1016/j.elspec.2025.147543","DOIUrl":"10.1016/j.elspec.2025.147543","url":null,"abstract":"<div><div>The development of high-performance cathode materials for lithium-ion batteries (LIBs) is crucial for advancing energy storage technologies. The electronic and thermal properties of lithium cuprate (Li₂CuO₂, LCO), a promising cathode material with mixed ionic and electronic conductivity were investigated. Using a two-step computational approach, Density Functional Theory (DFT) was employ to calculate the band structure and density of states (DOS) at room temperature, revealing a direct bandgap of 1.61 eV and semiconductor-like behavior. Additionally, X-ray Absorption Fine Structure (XAFS) spectroscopy utilized to probe the temperature-dependent electronic and structural dynamics of LCO, ranging from 253 K to 473 K. The results demonstrate the stability of the Cu-O blocks under elevated temperatures, highlighting their resilience during charge-discharge cycles. The Debye-Waller factor (DWF) analysis further confirms the material's moderate thermal conductivity and structural integrity, making LCO a viable candidate for high-temperature LIB applications. This comprehensive study provides valuable insights into the electronic and thermal behavior of LCO, paving the way for the design of next-generation cathode materials with enhanced electrochemical performance and thermal stability.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147543"},"PeriodicalIF":1.8,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170577","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}
We present experimental results on the impact energy dependence of L-subshell x-ray yields and production cross sections for the thick lead target (Pb, Z = 82) under impact of 15–30 keV electrons. Results are compared with the simulation data from the Monte Carlo Penelope code with the Distorted Wave Born Approximation (DWBA) formulations. The comparison yields fairly good agreement for the L-shell x-ray yields within the experimental uncertainties. Furthermore, the present results of the intensity ratio of and lines to the intensity of and their corresponding x-ray production cross sections are compared with available experimental and theoretical data; the agreement is found to be satisfactory. X-ray production cross sections for L-shell x-rays are derived by employing the thick target method (An et al., 2006). Furthermore, we have presented for the first time the experimental results on yield and x-ray production cross sections of the line and have compared the results with the simulation data; the agreement between two results is found to be good within the error bars of the measurements.
我们给出了在15-30 keV电子冲击下厚铅靶（Pb, Z = 82）的l -亚壳层x射线产率和产生截面的影响能量依赖的实验结果。结果与蒙特卡洛Penelope代码的模拟数据进行了比较，并采用畸变波Born近似（DWBA）公式。比较结果表明，在实验不确定度范围内，l壳层x射线产率的一致性相当好。同时，将Lβ、Lγ和Ll谱线强度与Lα谱线强度之比及其对应的x射线产生截面与已有的实验和理论数据进行了比较；协议是令人满意的。采用厚靶法推导了l壳层x射线的x射线产生截面（An et al., 2006）。此外，我们还首次给出了Ll线产率和x射线产率截面的实验结果，并将结果与模拟数据进行了比较；在测量误差范围内，两种结果的一致性较好。
{"title":"Experimental determination of L-subshells x-ray yields and production cross sections of thick lead (Z=82) element by impact of 15–30 keV electrons","authors":"Kailash Verma , Hitesh Rahangdale , Kumar Ankit Upadhayay , Raj Singh , Bhupendra Singh , Namita Yadav","doi":"10.1016/j.elspec.2025.147541","DOIUrl":"10.1016/j.elspec.2025.147541","url":null,"abstract":"<div><div>We present experimental results on the impact energy dependence of L-subshell x-ray yields and production cross sections for the thick lead target (Pb, Z = 82) under impact of 15–30 keV electrons. Results are compared with the simulation data from the Monte Carlo Penelope code with the Distorted Wave Born Approximation (DWBA) formulations. The comparison yields fairly good agreement for the L-shell x-ray yields within the experimental uncertainties. Furthermore, the present results of the intensity ratio of <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>β</mi></mrow></msub><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>γ</mi></mrow></msub></mrow></math></span> and <span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>l</mi></mrow></msub></math></span> lines to the intensity of <span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span> and their corresponding x-ray production cross sections are compared with available experimental and theoretical data; the agreement is found to be satisfactory. X-ray production cross sections for L-shell x-rays are derived by employing the thick target method (An et al., 2006). Furthermore, we have presented for the first time the experimental results on yield and x-ray production cross sections of the <span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>l</mi></mrow></msub></math></span> line and have compared the results with the simulation data; the agreement between two results is found to be good within the error bars of the measurements.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147541"},"PeriodicalIF":1.8,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900326","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}
The structural, magnetic and electronic properties of FeNi ( = 0.32, 0.36, 0.40, 0.50) alloys have been investigated using synchrotron based x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometer and the high resolution x-ray photoelectron spectroscopy (XPS) measurements. The XRD measurement was done down to 50 K temperature. The XRD studies suggest a single phase with fcc structure for = 0.36, 0.40, and 0.50 alloys and a mixed phase for = 0.32 alloy containing both bcc and fcc structures. The lattice parameter of the alloys exhibits a linear dependence on temperature giving rise to a temperature independent coefficient of thermal expansion (CTE). The lowest CTE is observed for = 0.36 Invar alloy as expected while = 0.50 alloy exhibits the highest CTE among the alloys studied. The CTE of the fcc component of mixed phase alloy is close to that of Invar alloy. The temperature dependence of magnetization of the alloys down to 2 K reveals an overall antiferromagnetic interactions within the ferromagnetic phase causing the magnetization decreasing with lowering temperature. The field cooled and zero field cooled data show larger differences for the Invar compositions; this is also manifested in the magnetic hysteresis data at 2 K and 300 K. The Fe 2 and Ni 2 core level spectra exhibit spin–orbit split features along with a satellite feature in the Ni 2 spectra. The spectral line shapes are almost similar for all the compositions studied. Interestingly, the spin–orbit splitting for Fe 3 spectra is larger than that observed for Ni 3 suggesting additional contributions due to the exchange interaction between the Fe 3 core hole with the Fe 3 moment. This suggests large magnetic moment contribution from Fe as expected. The core level and valence band spectra, and the magnetization data suggest significant role of disorder for the Invar compositions.
{"title":"Electronic, magnetic and thermal behavior near the Invar compositions of Fe-Ni alloys","authors":"Ananya Sahoo , Ayusa Aparupa Biswal , S.K. Parida , V.R.R. Medicherla , Soumya Shephalika Behera , M.N. Singh , A. Sagdeo , Sawani Datta , Abhishek Singh , Kalobaran Maiti","doi":"10.1016/j.elspec.2025.147540","DOIUrl":"10.1016/j.elspec.2025.147540","url":null,"abstract":"<div><div>The structural, magnetic and electronic properties of Fe<span><math><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></math></span>Ni<span><math><msub><mrow></mrow><mrow><mi>x</mi></mrow></msub></math></span> (<span><math><mi>x</mi></math></span> = 0.32, 0.36, 0.40, 0.50) alloys have been investigated using synchrotron based x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometer and the high resolution x-ray photoelectron spectroscopy (XPS) measurements. The XRD measurement was done down to 50 K temperature. The XRD studies suggest a single phase with fcc structure for <span><math><mi>x</mi></math></span> = 0.36, 0.40, and 0.50 alloys and a mixed phase for <span><math><mi>x</mi></math></span> = 0.32 alloy containing both bcc and fcc structures. The lattice parameter of the alloys exhibits a linear dependence on temperature giving rise to a temperature independent coefficient of thermal expansion (CTE). The lowest CTE is observed for <span><math><mi>x</mi></math></span> = 0.36 Invar alloy as expected while <span><math><mi>x</mi></math></span> = 0.50 alloy exhibits the highest CTE among the alloys studied. The CTE of the fcc component of mixed phase alloy is close to that of Invar alloy. The temperature dependence of magnetization of the alloys down to 2 K reveals an overall antiferromagnetic interactions within the ferromagnetic phase causing the magnetization decreasing with lowering temperature. The field cooled and zero field cooled data show larger differences for the Invar compositions; this is also manifested in the magnetic hysteresis data at 2 K and 300 K. The Fe 2<span><math><mi>p</mi></math></span> and Ni 2<span><math><mi>p</mi></math></span> core level spectra exhibit spin–orbit split features along with a satellite feature in the Ni 2<span><math><mi>p</mi></math></span> spectra. The spectral line shapes are almost similar for all the compositions studied. Interestingly, the spin–orbit splitting for Fe 3<span><math><mi>p</mi></math></span> spectra is larger than that observed for Ni 3<span><math><mi>p</mi></math></span> suggesting additional contributions due to the exchange interaction between the Fe 3<span><math><mi>p</mi></math></span> core hole with the Fe 3<span><math><mi>d</mi></math></span> moment. This suggests large magnetic moment contribution from Fe as expected. The core level and valence band spectra, and the magnetization data suggest significant role of disorder for the Invar compositions.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147540"},"PeriodicalIF":1.8,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870690","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}
In order to analyze the fine structure of the energy distribution of secondary electrons generated through the cascade process, we measured the electron spectra of NFE metals (Li, Mg, Al, Ca, Ga, In), their compounds (Al2O3 and GaAs) and Fe as transition metal with a CMA-type analyzer with absolute gain. We propose that the spectrum obtained by differentiating the energy spectrum in a logarithmic representation (defined as DLS) can be used to evaluate the excitation function that generates the fine structure of the secondary electron energy distribution. We found that the fine structure of the energy distribution of secondary electrons in NFE metals is mainly due to emission through a cascade process generated by the electrons from plasmon decay, which was obtained from analyses of the DLS, the excitation function, the energy distribution of secondary electrons N(E), and the EELS spectra. In addition, slow Auger electrons also generate secondary electrons through the cascade process. In Al2O3, a fine structure of secondary electrons was generated by electrons excited to unoccupied states by inter-band transitions and inner-shell excitation. In GaAs, both contributions from plasmon decay and electrons excited to unoccupied states by inter-band transitions and inner-shell excitation were observed. Based on these findings, it is concluded that the fine structure of the energy distribution of the secondary electrons emitted in the cascade process is due to the following electrons: 1) electrons from plasmon decay, 2) slow Auger electrons, and 3) electrons excited to unoccupied states by inter-band transitions or inner-shell excitation. These fine structures are superimposed on the structure of the individual excitation by primary electrons.
为了分析通过级联过程产生的次级电子能量分布的精细结构，我们使用具有绝对增益的cma型分析仪测量了NFE金属（Li, Mg, Al, Ca, Ga, In）及其化合物（Al2O3和GaAs）和Fe作为过渡金属的电子能谱。我们提出用对数表示（定义为DLS）微分能谱得到的谱可以用来评价产生次级电子能量分布精细结构的激发函数。通过对DLS、激发函数、二次电子能量分布N(E)和EELS谱的分析，我们发现NFE金属中二次电子能量分布的精细结构主要是由等离子体衰变产生的电子通过级联过程发射所致。此外，慢俄歇电子还通过级联过程产生二次电子。在Al2O3中，电子通过带间跃迁和内壳层激发激发到未占据态，产生了精细的二次电子结构。在砷化镓中，观察到等离子体衰变和电子被带间跃迁和内壳层激发激发到未占据态的贡献。基于这些发现，得出了级联过程中发射的次级电子能量分布的精细结构是由以下电子引起的：1)等离子体衰变产生的电子，2)慢俄歇电子，3)带间跃迁或内壳层激发激发到未占据态的电子。这些精细结构叠加在由初级电子激发的单个结构上。
{"title":"Fine structure of spectra for secondary electron excited by electron impact – Novel spectrum data analysis and application to nearly free electron metals","authors":"Satoshi Hashimoto , Tsuguo Sakurada , Shigeo Tanuma , Keisuke Goto , Takaharu Nagatomi","doi":"10.1016/j.elspec.2025.147539","DOIUrl":"10.1016/j.elspec.2025.147539","url":null,"abstract":"<div><div>In order to analyze the fine structure of the energy distribution of secondary electrons generated through the cascade process, we measured the electron spectra of NFE metals (Li, Mg, Al, Ca, Ga, In), their compounds (Al<sub>2</sub>O<sub>3</sub> and GaAs) and Fe as transition metal with a CMA-type analyzer with absolute gain. We propose that the spectrum obtained by differentiating the energy spectrum in a logarithmic representation (defined as DLS) can be used to evaluate the excitation function that generates the fine structure of the secondary electron energy distribution. We found that the fine structure of the energy distribution of secondary electrons in NFE metals is mainly due to emission through a cascade process generated by the electrons from plasmon decay, which was obtained from analyses of the DLS, the excitation function, the energy distribution of secondary electrons <em>N(E)</em>, and the EELS spectra. In addition, slow Auger electrons also generate secondary electrons through the cascade process. In Al<sub>2</sub>O<sub>3</sub>, a fine structure of secondary electrons was generated by electrons excited to unoccupied states by inter-band transitions and inner-shell excitation. In GaAs, both contributions from plasmon decay and electrons excited to unoccupied states by inter-band transitions and inner-shell excitation were observed. Based on these findings, it is concluded that the fine structure of the energy distribution of the secondary electrons emitted in the cascade process is due to the following electrons: 1) electrons from plasmon decay, 2) slow Auger electrons, and 3) electrons excited to unoccupied states by inter-band transitions or inner-shell excitation. These fine structures are superimposed on the structure of the individual excitation by primary electrons.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147539"},"PeriodicalIF":1.8,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824538","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 : 2025-04-04DOI: 10.1016/j.elspec.2025.147538
Saki Imada , Frank M.F. de Groot
Geometry dependences of partial fluorescence yield (PFY) spectra at the L2,3-edge of 3d transition metals are discussed theoretically and experimentally for high-spin 3d5 systems in Oh and Td point symmetries. Firstly, linear polarized light's propagation direction selection rules for a two-photon process are applied to 2p3d-PFY spectroscopy. Then, the 2p3d-PFY spectra were analyzed by comparison with spectra obtained as partial integration of 2p3d-resonant inelastic X-ray scattering (RIXS) signals, utilizing the relationship between PFY and RIXS spectroscopies: the former is an integration of yield of emitted light at each excitation energy, and the latter is a dispersion of emitted light as a function of emission energy at each excitation energy. Thus, a PFY spectrum can be divided into super PFY (sPFY) spectra using partial integrations of signals on a RIXS map, such as sPFY spectra from elastic and inelastic signals. It is suggested that the origin of the large deviation of 2p3d-PFY spectral shape in a linear-horizontal geometry from a true X-ray absorption spectrum is due to the lack of elastic signals, i.e., the lack of signals emitted when the system returns to its ground state. Contrary to a 2p3d-PFY spectrum, a 2p3s-PFY spectrum is often assumed to have a one-to-one correspondence with true XAS; however, 2p3s-PFY spectroscopy is also a two-photon process that abides by the propagation direction selection rules. We will show theoretically that 2p3s-PFY spectral shapes show a geometry dependence and offer a way to obtain a true X-ray absorption structure from a combination of 2p3s-PFY spectra in linear-vertical and linear-horizontal geometries.
{"title":"Geometry-dependent analysis of 2p3d- and 2p3s-partial fluorescence yield spectra for high-spin 3d5 systems","authors":"Saki Imada , Frank M.F. de Groot","doi":"10.1016/j.elspec.2025.147538","DOIUrl":"10.1016/j.elspec.2025.147538","url":null,"abstract":"<div><div>Geometry dependences of partial fluorescence yield (PFY) spectra at the L<sub>2,3</sub>-edge of 3d transition metals are discussed theoretically and experimentally for high-spin 3d<sup>5</sup> systems in O<sub>h</sub> and T<sub>d</sub> point symmetries. Firstly, linear polarized light's propagation direction selection rules for a two-photon process are applied to 2p3d-PFY spectroscopy. Then, the 2p3d-PFY spectra were analyzed by comparison with spectra obtained as partial integration of 2p3d-resonant inelastic X-ray scattering (RIXS) signals, utilizing the relationship between PFY and RIXS spectroscopies: the former is an integration of yield of emitted light at each excitation energy, and the latter is a dispersion of emitted light as a function of emission energy at each excitation energy. Thus, a PFY spectrum can be divided into super PFY (sPFY) spectra using partial integrations of signals on a RIXS map, such as sPFY spectra from elastic and inelastic signals. It is suggested that the origin of the large deviation of 2p3d-PFY spectral shape in a linear-horizontal geometry from a true X-ray absorption spectrum is due to the lack of elastic signals, i.e., the lack of signals emitted when the system returns to its ground state. Contrary to a 2p3d-PFY spectrum, a 2p3s-PFY spectrum is often assumed to have a one-to-one correspondence with true XAS; however, 2p3s-PFY spectroscopy is also a two-photon process that abides by the propagation direction selection rules. We will show theoretically that 2p3s-PFY spectral shapes show a geometry dependence and offer a way to obtain a true X-ray absorption structure from a combination of 2p3s-PFY spectra in linear-vertical and linear-horizontal geometries.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147538"},"PeriodicalIF":1.8,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769297","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 : 2025-03-10DOI: 10.1016/j.elspec.2025.147535
R.O. Kuzian , E.E. Krasovskii
Attosecond dynamics of electron reflection from a thin film is studied based on a one-dimensional jellium model. Following the Eisenbud–Wigner–Smith concept, the reflection time delay is calculated as the energy derivative of the phase of the complex reflection amplitude . For a purely elastic scattering by a jellium slab of a finite thickness the transmission probability oscillates with the momentum in the solid with a period , and closely follows these oscillations. The reflection delay averaged over an energy interval grows with , but in the limit of the amplitude becomes real, so vanishes. This picture changes substantially with the inclusion of an absorbing potential : As expected, for a sufficiently thick slab the reflection amplitude now tends to its asymptotic value for a semi-infinite crystal. Interestingly, for , around the maxima, the curve strongly deviates from , showing a narrow dip just at the maximum for . An analytical theory of this counterintuitive behavior is developed.
{"title":"Attosecond dynamics of electron scattering by an absorbing layer","authors":"R.O. Kuzian , E.E. Krasovskii","doi":"10.1016/j.elspec.2025.147535","DOIUrl":"10.1016/j.elspec.2025.147535","url":null,"abstract":"<div><div>Attosecond dynamics of electron reflection from a thin film is studied based on a one-dimensional jellium model. Following the Eisenbud–Wigner–Smith concept, the reflection time delay <span><math><mrow><mi>Δ</mi><msub><mrow><mi>τ</mi></mrow><mrow><mtext>r</mtext></mrow></msub></mrow></math></span> is calculated as the energy derivative of the phase of the complex reflection amplitude <span><math><mi>r</mi></math></span>. For a purely elastic scattering by a jellium slab of a finite thickness <span><math><mi>d</mi></math></span> the transmission probability <span><math><mi>T</mi></math></span> oscillates with the momentum <span><math><mi>K</mi></math></span> in the solid with a period <span><math><mrow><mi>π</mi><mo>/</mo><mi>d</mi></mrow></math></span>, and <span><math><mrow><mi>Δ</mi><msub><mrow><mi>τ</mi></mrow><mrow><mtext>r</mtext></mrow></msub></mrow></math></span> closely follows these oscillations. The reflection delay averaged over an energy interval grows with <span><math><mi>d</mi></math></span>, but in the limit of <span><math><mrow><mi>d</mi><mo>→</mo><mi>∞</mi></mrow></math></span> the amplitude <span><math><mi>r</mi></math></span> becomes real, so <span><math><mrow><mi>Δ</mi><msub><mrow><mi>τ</mi></mrow><mrow><mtext>r</mtext></mrow></msub></mrow></math></span> vanishes. This picture changes substantially with the inclusion of an absorbing potential <span><math><mrow><mo>−</mo><mi>i</mi><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub></mrow></math></span>: As expected, for a sufficiently thick slab the reflection amplitude now tends to its asymptotic value for a semi-infinite crystal. Interestingly, for <span><math><mrow><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>≠</mo><mn>0</mn></mrow></math></span>, around the <span><math><mrow><mi>T</mi><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span> maxima, the <span><math><mrow><mi>Δ</mi><msub><mrow><mi>τ</mi></mrow><mrow><mtext>r</mtext></mrow></msub><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span> curve strongly deviates from <span><math><mrow><mi>T</mi><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span>, showing a narrow dip just at the <span><math><mrow><mi>Δ</mi><msub><mrow><mi>τ</mi></mrow><mrow><mtext>r</mtext></mrow></msub><mrow><mo>(</mo><mi>E</mi><mo>)</mo></mrow></mrow></math></span> maximum for <span><math><mrow><msub><mrow><mi>V</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>=</mo><mn>0</mn></mrow></math></span>. An analytical theory of this counterintuitive behavior is developed.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147535"},"PeriodicalIF":1.8,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610416","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 : 2025-03-06DOI: 10.1016/j.elspec.2025.147524
S. Tricot , H. Ikeda , H.C. Tchouekem , J.-C. Le Breton , S. Yasuda , P. Krüger , P. Le Fèvre , D. Sébilleau , T. Jaouen , P. Schieffer
Photoelectron diffraction (PED) is a powerful spectroscopic technique that combines elemental resolution with a high sensitivity to the local atomic arrangement at crystal surfaces, thus providing unique fingerprints of selected atomic sites in matter. Stimulated by the rapid innovation in the development of various analysis methods for probing the atomic and electronic structures of van der Waals (vdW) heterostructures of two-dimensional materials, we present a theoretical assessment of the capacity of PED for extracting structural properties such as stacking, twist angles and interlayer distances. We provide a complete description of PED for the benchmark vdW heterostructure bilayer graphene (BLG), by calculating and analyzing the PED of BLG in Bernal and AA-stacking as well as twisted BLG for a wide range of the twist angle.
{"title":"Photoelectron diffraction of twisted bilayer graphene","authors":"S. Tricot , H. Ikeda , H.C. Tchouekem , J.-C. Le Breton , S. Yasuda , P. Krüger , P. Le Fèvre , D. Sébilleau , T. Jaouen , P. Schieffer","doi":"10.1016/j.elspec.2025.147524","DOIUrl":"10.1016/j.elspec.2025.147524","url":null,"abstract":"<div><div>Photoelectron diffraction (PED) is a powerful spectroscopic technique that combines elemental resolution with a high sensitivity to the local atomic arrangement at crystal surfaces, thus providing unique fingerprints of selected atomic sites in matter. Stimulated by the rapid innovation in the development of various analysis methods for probing the atomic and electronic structures of van der Waals (vdW) heterostructures of two-dimensional materials, we present a theoretical assessment of the capacity of PED for extracting structural properties such as stacking, twist angles and interlayer distances. We provide a complete description of PED for the benchmark vdW heterostructure bilayer graphene (BLG), by calculating and analyzing the PED of BLG in Bernal and AA-stacking as well as twisted BLG for a wide range of the twist angle.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147524"},"PeriodicalIF":1.8,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551406","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 : 2025-03-04DOI: 10.1016/j.elspec.2025.147527
Jun Zhang , Jianhui Jin , Yujie Zhao , Jize Sun , Weifeng Wang
1,3-Butadiene is a crucial intermediate in hydrocarbon combustion and pyrolysis processes and plays a significant role as a precursor in the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. This study investigates the low-pressure and high-temperature pyrolysis of 1,3-butadiene by using a newly designed silicon carbide (SiC) tubular flow microreactor, in combination with supersonic molecular beam sampling, synchrotron radiation vacuum ultraviolet single-photon ionization, and reflective time-of-flight mass spectrometry (SR-VUV-TOF-PIMS). We identified 36 pyrolysis products, ranging in mass-to-charge ratio (m/z) from 15 to 128, which included free radicals and isomeric species. The study determined the initial pyrolysis temperature of the parent compound and the initial formation temperatures of the products. Comparative analysis of our results with previous literature revealed the primary cleavage pathways in this work: 1,3-C4H6 → C2H4 + C2H2, 1,3-C4H6 → 1,2-C4H6, 1,2-C4H6 → C3H3· + CH3·, 1,3-C4H6 + C3H3· → C3H4 + C4H5·, 1,3-i-C4H5· → C4H4 + H· and 1,3-n-C4H5· → C4H4 + H·. These studies contribute valuable insights into the mechanisms of hydrocarbon combustion and pyrolysis, as well as the reference for the formation processes of PAHs and soot.
{"title":"Experimental study on low-pressure and high-temperature pyrolysis of 1, 3-butadiene using synchrotron radiation and SiC flash microreactor","authors":"Jun Zhang , Jianhui Jin , Yujie Zhao , Jize Sun , Weifeng Wang","doi":"10.1016/j.elspec.2025.147527","DOIUrl":"10.1016/j.elspec.2025.147527","url":null,"abstract":"<div><div>1,3-Butadiene is a crucial intermediate in hydrocarbon combustion and pyrolysis processes and plays a significant role as a precursor in the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. This study investigates the low-pressure and high-temperature pyrolysis of 1,3-butadiene by using a newly designed silicon carbide (SiC) tubular flow microreactor, in combination with supersonic molecular beam sampling, synchrotron radiation vacuum ultraviolet single-photon ionization, and reflective time-of-flight mass spectrometry (SR-VUV-TOF-PIMS). We identified 36 pyrolysis products, ranging in mass-to-charge ratio (<em>m/z</em>) from 15 to 128, which included free radicals and isomeric species. The study determined the initial pyrolysis temperature of the parent compound and the initial formation temperatures of the products. Comparative analysis of our results with previous literature revealed the primary cleavage pathways in this work: 1,3-C<sub>4</sub>H<sub>6</sub> → C<sub>2</sub>H<sub>4</sub> + C<sub>2</sub>H<sub>2</sub>, 1,3-C<sub>4</sub>H<sub>6</sub> → 1,2-C<sub>4</sub>H<sub>6</sub>, 1,2-C<sub>4</sub>H<sub>6</sub> → C<sub>3</sub>H<sub>3</sub>· + CH<sub>3</sub>·<sub>,</sub> 1,3-C<sub>4</sub>H<sub>6</sub> + C<sub>3</sub>H<sub>3</sub>· → C<sub>3</sub>H<sub>4</sub> + C<sub>4</sub>H<sub>5</sub>·, 1,3-i-C<sub>4</sub>H<sub>5</sub>· → C<sub>4</sub>H<sub>4</sub> + H· and 1,3-n-C<sub>4</sub>H<sub>5</sub>· → C<sub>4</sub>H<sub>4</sub> + H·. These studies contribute valuable insights into the mechanisms of hydrocarbon combustion and pyrolysis, as well as the reference for the formation processes of PAHs and soot.</div></div>","PeriodicalId":15726,"journal":{"name":"Journal of Electron Spectroscopy and Related Phenomena","volume":"280 ","pages":"Article 147527"},"PeriodicalIF":1.8,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551405","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号