EPJ D Highlight – Estimating uncertainty in atomic spectroscopy
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- Published on 17 April 2024

A numerical toolbox offers a robust way to evaluate uncertainty in atomic wavelength measurements.
If you repeat a measurement with the same or different instruments, you’ll get slightly different numbers each time. Estimating the uncertainties associated with these numbers turns them into an informative result. In a study published in EPJ D, Alexander Kramida, of the National Institute of Standards and Technology in Maryland, USA, now explains a new statistical approach for estimating the uncertainty associated with atomic spectroscopy measurements. He discusses how this approach can be applied both to measurements of spectral line wavelengths, and to other atomic properties that are indirectly determined from them.
EPJ D Topical Issue: Dynamics and Photodynamics: From Isolated Molecules to the Condensed Phase
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- Published on 17 January 2024

Guest Editors: Luis Bañares, Ramón Hernández-Lamoneda, Pascal Larregaray, Germán Rojas-Lorenzo and Jesús Rubayo-Soneira
Dynamics and photodynamics: from isolated molecules to the condensed phase is a highly interdisciplinary topical issue with numerous connections between traditional branches of physics and chemistry.
The issue provides a snapshot of current research in different areas of molecular systems science. It consists of 12 contributions representing both experimental and theoretical studies, ranging from fundamental mechanisms to more applied levels, which are essential in numerous applications of nanotechnology and material science. The contributions featured in this issue encompass a wide range of areas, including spectroscopy, photodissociation, dynamics of reactions involving neutral and charged cluster systems, carbon nanotubes and various other subjects.
This topical issue is celebrating the 20th anniversary of the Photodynamics Conference, held in Havana in November 2022.
All articles are available here and are freely accessible until 15 March 2024. For further information read the Editorial.
EPJ D Topical Issue: Physics of Ionized Gases and Spectroscopy of Isolated Complex Systems: Fundamentals and Applications
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- Published on 06 November 2023

Guest Editors: Bratislav Obradović, Jovan Cvetić, Dragana Ilić, Vladimir Srećković and Sylwia Ptasinska
This EPJ D Topical Issue presents selected papers covering a wide range of topics from fundamental studies to applications of ionized gases: Atomic Collision Processes - Electron and Photon Interactions with Atomic Particles, Heavy Particle Collisions, Swarms and Transport Phenomena; Particle and Laser Beam Interactions with Solids - Atomic Collisions in Solids, Sputtering and Deposition, Laser and Plasma Interaction with Surfaces; Low Temperature Plasmas - Plasma Spectroscopy and other Diagnostic Methods, Gas Discharges, Plasma Applications and Devices; General Plasmas - Fusion Plasmas, Astrophysical Plasmas and Collective Phenomena.
EPJ D Highlight - Creating optical logic gates from graphene nanoribbons
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- Published on 09 October 2023

A new graphene-based optical logic gate uses collective oscillations of electrons to process light waves in a far smaller space than existing designs. The device also benefits from low information loss and high stability.
Research into artificial intelligence (AI) network computing has made significant progress in recent years, but has so far been held back by the limitations of logic gates in conventional computer chips. Through new research published in EPJ D, a team led by Aijun Zhu at Guilin University of Electronic Technology, China, introduce a graphene-based optical logic gate, which addresses many of these challenges.
EPJ D Highlight - Machine learning hunts for the right mix of hydrogen isotopes for future nuclear fusion power plants
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- Published on 31 August 2023

New research is an initial step in the use of deep learning to help determine the right mix of hydrogen isotopes to use in fusion power plants of the future
The process that powers the stars, nuclear fusion, is proposed as a future power source for humanity and could provide clean and renewable energy free of the radioactive waste associated with current nuclear fission plants.
Just like the fusion process that sends energy spilling out from the Sun, future nuclear fusion facilities will slam together isotopes of the universe’s lightest element, hydrogen, in an ultra-hot gas or “plasma” contained by a powerful magnetic field to create helium with the difference in mass harvested as energy.
One thing that scientists must know before the true advent of fusion power here on Earth is what mix of hydrogen isotopes to use— primarily “standard” hydrogen, with one proton in its atomic nucleus, deuterium with one proton and one neutron in its nucleus, and tritium with a nucleus of one proton and two neutrons. This is currently done with spectroscopy for prototype fusion devices called tokamaks, but this analysis can be time-consuming.
In a new paper in EPJ D, author Mohammed Koubiti, Associate Professor at the Aix-Marseille Universite, France, assesses the use of machine learning in connection with plasma spectroscopy to determine the ratios of hydrogen isotopes for nuclear fusion plasma performance.
EPJ D Topical Issue: Electron-Driven Processes from Single Collisions to High-Pressure Plasmas
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- Published on 30 August 2023

Guest Editors: Jose L. Lopez, Michael Brunger, and Holger Kersten
The special Topical Issue of the European Physics Journal D (EPJ D) on “Electron-Driven Processes from Single Collisions to High-Pressure Plasmas” is published to honor Kurt H. Becker, who served as Editor-in-Chief for the journal from 2010 to 2016, on his 70th birthday. Electron-driven processes from single collisions to high-pressure plasmas definitely occupy a central position in atomic and plasma physics. Considering this, the Guest Editors compilated a broad range of original manuscripts that encompass the area of electron-atom and electron-molecular collisions, respectively, low-temperature plasma research and aligning with Kurt Becker’s emphasis on science innovation and entrepreneurship. Hence, the papers focus on various recent scientific and technological advances in this given area of physics, chemistry and technology of non-thermal plasmas.
EPJ D Highlight - Looking deeper into graphene using rainbow scattering
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- Published on 24 July 2023

New research uses protons to shine a light on the structure and imperfections of this two-dimensional wonder material
Graphene is a two-dimensional wonder material that has been suggested for a wide range of applications in energy, technology, construction, and more since it was first isolated from graphite in 2004.
This single layer of carbon atoms is tough yet flexible, light but with high resistance, with graphene calculated to be 200 times more resistant than steel and five times lighter than aluminium.
Graphene may sound perfect, but it very literally is not. Isolated samples of this 2D allotrope aren’t perfectly flat, with its surface rippled. Graphene can also feature structural defects that can, in some cases, be deleterious to its function and, in other instances, can be essential to its chosen application. That means that the controlled implementation of defects could enable fine-tuning of the desired properties of two-dimensional crystals of graphene.
In a new paper in EPJ D, Milivoje Hadžijojić and Marko Ćosić, both of the Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia, examine the rainbow scattering of photons passing through graphene and how it reveals the structure and imperfections of this wonder material.
EPJ D Highlight - Looking deeper into violent neutron star collisions to find the origins of heavy elements
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- Published on 21 July 2023

The gold that makes up your most precious jewellery may have been forged in a violent cosmic collision millions or billions of light years away between two neutron stars. New research seeks to better understand this process.
There is only a single confirmed site in the Universe capable of generating conditions extreme enough to initiate the production process for many of the heaviest elements in the Universe, including gold, platinum, uranium – neutron star mergers. These mergers are the only event observed to-date that can produce the incredible densities and temperatures needed to power the rapid neutron capture process.
In a new paper in EPJ D, Andrey Bondarev, a postdoc researcher at Helmholtz Institute Jena, James Gillanders a postdoc researcher in Rome, and their colleagues examine the spectra from the kilonova AT2017gfo to investigate the presence of forged tin, by looking for spectral features caused by its forbidden transitions.
EPJ D Topical Issue: Precision Physics of Simple Atomic Systems
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- Published on 17 July 2023

Guest Editors: Krzysztof Pachucki, Thomas Udem, Wim Ubachs, Paolo Crivelli & Stefan Ulmer
This EPJD special issue dedicated to the field of precision physics of simple atomic systems includes several important peer-reviewed contributions, presented on the 11th edition of the PSAS conference —initially planned to take place in May 2020 in Wuhan, China (only to be rescheduled 2 years later, in May 2022, due to the COVID-19 pandemic, in Warsaw, Poland).
The aim of the PSAS conference is to gather scientists from all over the world working on precise calculations and measurements, with the goal to test fundamental physics, to verify laws of physics, and to determine fundamental constants. Correspondingly, a mix of theoretical, numerical and experimental works spanning the fields of spectroscopy of atomic and molecular hydrogen, QED of few-electron bound systems, exotic atoms and ions, searches for BSM physics with atoms and antimatter, clocks, measurements of g-2 and alpha, originating from several of the major groups in this field, are reported here, making the current collection of interest for both the younger generation entering this research field and experts for efficient access on recent developments.
All articles are available here and are freely accessible until 29 August 2023. For further information read the Editorial.
EPJ D Highlight - Testing a perfect absorber metamaterial
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- Published on 17 July 2023

The proposed metamaterial could have a wide range of applications, from sensing to stealth technology
Metamaterials are a type of artificial material which, as the prefix “meta” – meaning in Greek “after” or “beyond” – indicates, demonstrate electromagnetic properties and other characteristics not found in nature.
As a result of these characteristics, including negative refraction and perfect lensing and cloaking, which arise from the lattice design composition of these substances rather than the materials that actually comprise them, metamaterials have become a hot research topic.
In particular, materials scientists are actively hunting for metamaterials that are “perfect absorbers” of electromagnetic radiation with controllable resonance characteristics that lead to their wide usage in applications as varied as solar cells, thermal radiation imaging, sensing technology, and even stealth technology.
In a new paper in EPJ D, Shahzad Anwar, a researcher at the Department of Physics, Islamia College Peshawar, Pakistan, and his colleagues document the proposed design of a triple-band perfect metamaterial absorber. The new metamaterial could have applications in sensors, filters, and in stealth technology.