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Chemische Prozesse und Phasenübergänge Poster: Mi., 14:00–16:30 M-P173
Studying Chemical Processes by Pulse Radiolysis
Eberhard Janata 1
1 Hahn-Meitner-Institut Berlin, Glienicker Str. 100, 14109 Berlin
Studying Chemical Processes by Pulse Radiolysis E. Janata Hahn-Meitner-Institut
Berlin GmbH, Bereich Solarenergieforschung Glienicker Str. 100, 14109 Berlin
The impact of a pulse of high-energy electrons creates electron-hole pairs in solids, or
forms a number of reducing or oxidizing species in solutions. Electrons and holes can
move and recombine independently or are trapped by structural defects or impurities.
In solution, the species created can reduce or oxidize additives nearly instantaneously,
which may be the starting point for a sequence of chemical reactions. These processes
can be detected in solids, such as glasses or glassy-crystalline materials, and in
solutions in situ by means of optical methods. Conductometric methods are also applicable,
either simultaneously with the optical or as stand-alone methods. After a short
introduction to the pulse radiolysis apparatus of the 4 MeV van de Graaff accelerator
facility ELBENA at the Hahn-Meitner-Institut, three examples are given. Firstly, the
formation and disappearance of a short-lived thallium-silver cluster in aqueous solution
is discussed. Secondly, the concentration of nitrous oxide in aqueous solutions of
different contents of NaCl or LiCl is measured, thus representing a kinetic method for
the determination of the salting-out effect. Thirdly, optical emission and absorption
spectra of a bariumsilicate glass are compared with the results obtained with a fused
quartz.