Knowledge Bank

Using a classical flush spectroscopic apparatus delivering about 1500 J with a 5 $\mu s$ duration at half intensity and only 5% of the maximum intensity still present after 20 $\mu s$ we have examined iodine and triodide ions in aqueous solutions. With very pure iodine solutions, we have noted a transient absorption presenting two maxima, one at 375 nm and the other at 390 nm, which we assigned to $Iaq$. No absorption appears in the infrared up to 900 nm. When flashing triodide solutions a transient species is observed which absorbs in the near U.V. with a maximum at 340 nm and in the infrared with maxima at 700 and 800 nm. This species is already known as the $I2-$ion. Recombination kinetics, extinction coefficient, temperature effects and quantum yield of cage escape will be discussed.