The production of vibrationally excited hydroxyl radicals under isothermal conditions by flash photolysis

The flash photolysis of ozone in the presence of ammonia, hydrogen, hydrogen chloride, methane and water has been investigated under isothermal conditions. In each case the presence of vibrationally excited hydroxyl radicals has been shown spectroscopically. The concentration of these species is highest at the shortest time (i.e. during the photolysis flash) and decreases rapidly to below detectable limits within about 20 μs. The hydroxyl radical is produced by the reaction O( 1 D ) + HR -> OH + R + 29 to 46 kcal rotationally cold but with up to at least two quanta of vibrational energy, the energy for which is supplied by the electronic energy of the oxygen atom. Under some conditions, the spectrum of oxygen molecules with up to 16 quanta of vibrational energy is also seen and shows that the reaction competes successfully with the hydrogen abstraction reaction. O( 1 D ) + O 2 -> O 2 * + O 2 competes successfully with the hydrogen abstraction reaction.