We present quantitative measurements of the photoassociation of cesium molecules inside a far-detuned optical dipole trap. A model of the trap depletion dynamics is derived which allows to extract absolute photoassociation rate coefficients for the initial single-photon photoassociation step from measured trap-loss spectra. The sensitivity of this approach is demonstrated by measuring the Franck-Condon modulation of the weak photoassociation transitions into the low vibrational levels of the outer well of the 0g- state that correlates to the 6s+6p3/2 asymptote. The measurements are compared to theoretical predictions. In a magneto-optical trap these transitions have previously only been observed indirectly through ionization of ground state molecules.
We study the photoassociative collisional loss of laser-cooled Rb atoms from a far-off resonance optical dipole force atom trap. We obtain a well-resolved photoassociation spectrum from 50 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ to 980 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ below the first excited dissociation limit of the
Rb2 molecule. Two vibrational series associated with excited
Rb2 $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathit{g}}^{+}$ states are clearly visible. Oscillations in the associated Franck-Condon factors reflect the structure of the triplet ground state wave function. Our results clearly demonstrate the potential of photoassociation spectroscopy as a new probe of molecular structure.
We present high-level four-component coupled cluster and multireference configuration interaction calculations of potential energy curves, dipole moment, Franck-Condon factors and spectroscopic constants of the newly formed RbYb molecule. From finite-field calculations we obtain an electric dipole moment for RbYb of almost 1 D. In combination with its magnetic dipole moment this makes RbYb an excellent candidate for trapping and for studying dipolar interaction in the ultracold regime. Significant Franck-Condon factors are found between the rovibronic ground state and the lowest rovibrational levels of the first excited 2Sigma1/2+ state but also between a broad range of rovibrational levels of the 2Pi1/2 and 2Pi3/2 states. This allows for several two-step approaches to reach the rovibronic ground state after initial photoassociation.