Fano profiles in two-photon photoassociation spectra.

In this article we derive the lineshapes observed in two-photon photoassociation spectrocopy of molecules using an effective Hamiltonian adapted from previous work in atomic physics. The lineshape is decomposed in terms of sums and products of Breit-Wigner and Fano profiles, which we associate with physical absorption and emission processes, and to quantum interferences between transition amplitudes. We emphasize the specific features which do not exist in the atomic case, linked to the dissociation width of the photoassociated molecules in the electronic ground state.