MSGID: 1:317/3 6471876d   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Emergence of solvated dielectrons observed for the first time    
      
     Date:   
         May 26, 2023   
     Source:   
         University of Freiburg   
     Summary:   
         Scientists generate low-energy electrons using ultraviolet light.   
      
      
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   FULL STORY   
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   Solvated dielectrons are the subject of many hypotheses among scientists,   
   but have never been directly observed. They are described as a pair   
   of electrons that is dissolved in liquids such as water or liquid   
   ammonia. To make space for the electrons a cavity forms in the liquid,   
   which the two electrons occupy. An international research team around   
   Dr. Sebastian Hartweg, initially at Synchrotron SOLEIL (France), now at   
   the Institute of Physics at the University of Freiburg and Prof. Dr. Ruth   
   Signorell from ETH Zurich, including scientists from the synchrotron   
   SOLEIL and Auburn University (US) has now succeeded in discovering a   
   formation and decay process of the solvated dielectron. In experiments   
   at the synchrotron SOLEIL (DESIRS beamline), the consortium found direct   
   evidence supported by quantum chemical calculations for the formation   
   of these electron pairs by excitation with ultraviolet light in tiny   
   ammonia droplets containing a single sodium atom. The results were   
   recently published in the scientific journal Science.   
      
   Traces of an unusual process When dielectrons are formed by excitation   
   with ultraviolet light in tiny ammonia droplets containing a sodium atom,   
   they leave traces in an unusual process that scientists have now been able   
   to observe for the first time. In this process, one of the two electrons   
   migrates to the neighbouring solvent molecules, while at the same time   
   the other electron is ejected. "The surprising thing about this is that   
   similar processes have previously been observed mainly at much higher   
   excitation energies," says Hartweg. The team focused on this second   
   electron because there could be interesting applications for it. On the   
   one hand, the ejected electron is produced with very low kinetic energy,   
   so it moves very slowly. On the other hand, this energy can be controlled   
   by the irradiated UV light, which starts the whole process. Solvated   
   dielectrons could thus serve as a good source of low-energy electrons.   
      
   Generated specifically with variable energy Such slow electrons can   
   set a wide variety of chemical processes in motion. For example, they   
   play a role in the cascade of processes that lead to radiation damage in   
   biological tissue. They are also important in synthetic chemistry, where   
   they serve as effective reducing agents. By being able to selectively   
   generate slow electrons with variable energy, the mechanisms of such   
   chemical processes can be studied in more detail in the future. In   
   addition, the energy made available to the electrons in a controlled   
   manner might also be used to increase the effectiveness of reduction   
   reactions. "These are interesting prospects for possible applications   
   in the future," says Hartweg. "Our work provides the basis for this and   
   helps to understand these exotic and still enigmatic solvated dielectrons   
   a little better."   
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Inorganic_Chemistry # Physics # Chemistry # Spintronics   
             o Computers_&_Math   
                   # Spintronics_Research   
       * RELATED_TERMS   
             o Photoelectric_effect o Ozone o Electroluminescence o   
             Ultraviolet o Optics o Combustion o Solar_cell o Atom   
      
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   Story Source: Materials provided by University_of_Freiburg. Note:   
   Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Sebastian Hartweg, Jonathan Barnes, Bruce L. Yoder, Gustavo   
      A. Garcia,   
         Laurent Nahon, Evangelos Miliordos, Ruth Signorell. Solvated   
         dielectrons from optical excitation: An effective source of   
         low-energy electrons.   
      
         Science, 2023; DOI: 10.1126/science.adh0184   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230526142242.htm   
      
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