Res. Chem. Intermed.
, Vol. 31, No. 7–8, pp. 605–611 (2005)
Also available online - www.vsppub.com
Pulse radiolysis experiments at the ELBENA facility:
on the structure of the trimer silver cluster Ag
and the direct observation of aliphatic alcohol radicals
Hahn-Meitner-Institut Berlin, Glienicker Str. 100, 14109 Berlin, Germany
Received 16 February 2004; accepted 2 June 2004
Abstract—Two examples from the ﬁeld of physical chemistry are given here in order to demonstrate
the versatility of pulse radiolysis. In the study of the early stages in the growth of small silver
particles, the trimer silver cluster Ag
exhibits a pronounced position that this cluster represents
the changeover from pseudo-ﬁrst-order kinetics to second-order kinetics. An attempt will be made
to describe the structure of this species. The reaction of hydrogen atoms and hydroxyl radicals with
aliphatic alcohols is monitored by observing directly the absorption of the resultant radicals. As an
application, the reaction H
was studied by means of the absorption of alcohol radicals.
Keywords: Pulse radiolysis; trimer silver cluster; aliphatic alcohol radicals; hydrogen atom; hydroxyl
For the study of elementary chemical reactions, pulse radiolysis has been proven
to be a powerful instrument. Here, two examples from the opalescent word of
chemistry are reviewed. Recently, the trimer silver cluster has been identiﬁed during
the growth of silver clusters initiated by the reduction of silver ions in solution .
The reduced silver ion reacts in a two-step mechanism with bulk silver ions yielding
the trimer cluster. The formation of the trimer silver cluster was found to follow
strictly a pseudo-ﬁrst-order law with regard to the bulk silver ion concentration.
The subsequent reaction, i.e., the disappearance of the trimer silver cluster, follows
a second-order law despite the presence of a large amount of bulk silver ions. The
question what is special about the trimer silver cluster arises because it represents a
transition point in the reaction mechanism describing the growth of small silver
clusters in aqueous solution. In order to answer this question, a model of the