Vibrational Excitation of OH Resulting from H₂O Photodissociation

A model for the vibrational excitation of the OH(A 2 Σ + ) radical is developed with the aid of the Franck-Condon model and the half-collision model. The calculated vibrational distribution over levels 0, 1, 2, which is based on the Franck-Condon model, is 1, 0.27, 0.03; this is qualitatively in good agreement with the experiment by T. Carrington, 1, 0.3, <0.01. On the other hand, the force between the recoiling fragments negligibly alters the vibrational distribution. The vibrational motion of the OH radical, therefore, is excited simultaneously with an electronic excitation.