Photo-excitation of a Structured Continuum: A Soluble Model

The photoexcitation of a structured continuum of states from a single ground state is considered. We investigate an analytically soluble model in which the dipole matrix elements between the ground state and the continuum vary sinusoidally between zero and a maximum. The time-evolution of the ground-state population still exhibits the periodic disruption observed in the Bixon-Jortner model, although the disruption is much reduced. We allow the ground state to be resonant with an arbitrary place in the continuum; population trapping is observed in the case of resonance with a zero in the continuum. We compare and contrast the results obtained with this model with those of quasi-continuum excitation. Lastly, we examine the final-state spectrum.