Mechanism of dark decomposition of iodine donor in the active medium of a pulsed chemical oxygen-iodine laser

摘要

A scheme is proposed that describes the dark decomposition of iodide - the donor of iodine - and the relaxation of singlet oxygen in the chlorine-containing active medium of a pulsed chemical oxygen-iodine laser (COIL). For typical compositions of the active media of pulsed COILs utilising CH_3I molecules as iodine donors, a branching chain reaction of the CH_3I decomposition accompanied by the efficient dissipation of singlet oxygen is shown to develop even at the stage of filling the active volume. In the active media with CF_3I as the donor, a similar chain reaction is retarded due to the decay of CF_3 radicals upon recombination with oxygen. The validity of this mechanism is confirmed by a rather good agreement between the results of calculations and the available experimental data. The chain decomposition of alkyliodides accompanied by an avalanche production of iodine atoms represents a new way of efficient chemical production of iodine for a COIL.