Iodine monoxide

During daylight hours iodine monoxide, lO exists in a fast photochemical equilibrium with I, viz. 

Case Study V - Iodine monoxide chemistry in the coastal margins -Figure 23 shows the measured concentration of iodine monoxide (lO)... 

A likely source of active iodine is provided by the photolysis of methyl iodide (CH3f) and perhaps of other iodocarbons. As the atmospheric lifetime of CH3f is relatively short (a few days), the tropospheric abundance of this compound is generally lower than 10 pptv (Moyers and Duce, 1972 Singh et al., 1983 Atlas et al., 1993) although local maxima are found over the productive regions of the ocean (Oram and Penkett, 1994). If iodine atoms are released above the tropopause, they react with ozone to form the iodine monoxide radical... 

Wittrock, F., R. Mueller, A. Richter, H. Bovensmann, and J.P. Burrows, Measurements of iodine monoxide (IO) above Spitsbergen. Geophys Res Lett 27, 1471, 2000. 

The iodine monoxide (lO) self-reaction is relatively fast and yields mainly iodine dioxide (OlO) or I2O2 at the range of pressures in the lower atmosphere. The lO dimer formed via (8.4c) is hkely to undergo photolysis, be taken up onto existing aerosol surfaces or take part in nucleation processes leading to the formation of new particles in coastal marine environments (O Dowd and Hoffmann, 2002). 

Chlorine Monoxide (CIO), Bromine Monoxide (BrO), Iodine Monoxide (10)... 

Chlorine monoxide CIO, bromine monoxide BrO, and iodine monoxide lO are the main chain carrier of stratospheric and tropospheric halogen chain reactions. CIO is partially photolyzed only in the stratosphere, and the photolytic rates of BrO and lO are large also in the troposphere. Their photolysis rates have to be considered in the evaluation of ozone depleting chain reactions. 

---