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B.G. Ershov, E. Janata / Chemical Physics Letters 372 (2003) 195–198
The simulation also indicates that at the end of the
measurement Iꢀ is the main product while the
contributions of I2ꢀ or Iꢀ3 are almost negligible.
This is also demonstrated in Fig. 2 where at longer
times there is no absorption of Iꢀ2 or I3ꢀ,the latter
with its characteristic absorption bands at 280 nm
and 350 nm [7]. The lack of Iꢀ2 and I3ꢀ indicates that
equilibria (9) and (10) have shifted to the left.
From the computer simulation of the kinetic
curves at 725 nm and 230 nm,rate constants for
the reaction between iodine and the radical of
methanol,ethanol or 2-propanol were obtained to
therefore influence the stability of the iodide/iodine
system.
References
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be 5 ꢁ 109, 6:5 ꢁ 109,or 8 ꢁ 109 dm3 molꢀ1 sꢀ1
,
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4. Conclusions
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The extremely high rate constants for the reac-
tions of some 1-hydroxyalkyl radicals with iodine
show that they are diffusion controlled. These
values are higher the larger the reduction potential
of the 1-hydroxyalkyl radicals, )1.18, )1.25,or
)1.39 V for radicals from methanol,ethanol,or
2-propanol,respectively. It can be concluded that
the efficiency with which an electron is transferred
from the 1-hydroxyalkyl radical to iodine is de-
termined by the reducing power of the radical.
Photo-generated holes in nanostructured crys-
talline titanium dioxide can be reduced efficiently
by organic solvents [19,20]. As demonstrated
above,alcohol radicals can reduce iodine and can
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