FREE RADICALS are active and short-lived intermediates
which play important roles in chain-reaction systems such as combustion
and atmospheric chemical reaction processes.
Our research studies are dedicated to the elucidation of the complex
reaction processes through the direct observation of the free radicals and
Elucidation of Chein-Reaction Systems
A chain-reaction system consisting of multiple elementary reaction
steps of free radicals shows different behavior from those expected from
a simplefied one-step net reaction or from each constituent
For example, a chlorine atom (Cl) produced by a photolysis of a
fleon molecule in the stratosphere destroys ozone (O3
by the chain-reaction system consisting of the following two reactions
|Cl + O3 → ClO + O2 || (1)|
|ClO + O → Cl + O2 || (2)|
|O + O3 → 2 O2 (net reaction)|
The chlorine atom (Cl) reacts with an ozone molecule (1) and produces a ClO
radical, which eventually reproduces a chlorine atom by the reaction
Consequently, a Cl atom produced by a photolysis of a fleon molecule
destroys a number of ozone moleclues by this chain-reaction system.
Under a typical stratospheric condition, one Cl atom is estimated
to destroy about 104
Such a behavior cannot be captured from either from the net reaction
nor from the reaction (1) or (2) only.
To understand the free radical kinetics is to elucidate the
behavior of such a reaction network (or system) consisting of multiple
free radical = radical ?
The original meaning of the term radical is a group of
atoms in chemical coumpounds. For example, 'methyl radical'
(-CH3) and 'hydroxy radical' (-OH) in organic
coumpounds are radicals in its original meaning.
(But they would rather be called 'methyl group' and 'hydroxy group'
in recent terminology.)
When chemists started to use the word radical, a group called
radical had never been known to exist in isolation either directly
or indirectly, though some might imagine it. Thus, when the isolated
radicals came into observation of chemists, they needed
to be distinguished from groups in compounds and started to be called
'free radicals'. As the development of invesigation on free
radicals, the term radical became to mean 'free radicals'.
For example, in recent years, 'methyl (CH3) radical' means
free methyl radical rather than the methyl (-CH3) in
compounds. For this reason, the methyl in comnounds would better be
denoted as 'methyl group' rather than 'methyl radical'.