Abstract

Impulsive photodissociation of triiodide; I₃⁻ + hν → I₂⁻ + I has been demonstrated to generate vibrationally excited and phase coherent diiodide ion fragments in polar solvents¹. Investigations of the mechanisms which allow the phase coherent molecular evolution to transcend bond fission and solvent collisions, stresses the importance of symmetry breaking prior to excitation in molding product vibrational coherence². Centro-symmetric and linear I₃⁻ must decide which of its ends will become the I₂⁻ radical, and which atomic iodine. If this decision is postponed too long, collision with solvent may precede it and wash out phase coherence of nuclear motion. Preexisting broken symmetry facilitates a rapid dynamic decision. Subtler effects of a delayed decision involve deposition of excess energy into translation and vibration of the products again show advantages of early symmetry breaking in producing fragment coherence³. The purpose of the present study is to test this hypothesis by comparing dissociation dynamics from centro-symmetric and asymmetrical initial states.

© 1996 Optical Society of America