Reaction Dynamics of Aligned Molecules

Photofragmentation—also termed ‘half collision’—is a method to comprehend the complicated process of a chemical reaction (the ‘full collision’) better. The use of polarized light enabled the study of the spectroscopy of aligned molecules, yielding information about the photochemically produced intermediate state—the transition state. Even though stable reaction products were studied, the forces responsible for the motions of the fragments can be visualized. In this way a model can be constructed that represents the part of the potential hypersurface responsible for the observed motions. The application of this spectroscopic method to hydrogen peroxide H₂O₂ has become a classic example. The complex decomposition of hydrazoic acid, HN₃, represented a challenge, and its successful solution proves the general applicability of this method.