RESONANT SHORT-PULSE EFFECTS ON NUCLEAR MOTION IN THE ELECTRONIC GROUND-STATE

We investigate several approximate treatments of the pulse propagators describing the effects of electronically resonant ultrashort light pu lses on the states of molecules in condensed phases, including the cla ssical Franck approximation and a quadratic Hamiltonian treatment. Usi ng a Morse oscillator model of iodine, we examine the effects of the i nitial form and motion of the pump-induced nuclear density matrix incr ement on pump-probe signals. We also clarify the conditions of high te mperature and short-pulse duration under which the contribution of nuc lear dynamics in the electronic ground state to a pump-probe signal wi ll bear a definite sign.