Delayed and direct cage exit in photodissociation of Cl2 in solid Ar

The yield for photodissociation of Cl2 in solid Ar was measured experimentally as a function of photon energy and studied by molecular dynamics simulations. The results show that separation of the Cl fragments at low energies occurs by delayed exit (t3 ps) from the surrounding cage of Ar atoms. Above a photon threshold energy of 9.0 eV, there is a switchover to direct cage exit, in which the Cl impulsively knocks a cage atom out of its way. The results are a first demonstration of delayed cage exit and of changeover from delayed to direct exit in solid-state photolysis.