We present results from two-photon photoassociative spectroscopy of the least-bound vibrational level of the $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}_{g}^{+}$ state of the
88Sr2 dimer. Measurement of the binding energy allows us to determine the
s-wave scattering length ${a}_{88}=\ensuremath{-}1.4(6){a}_{0}$. For the intermediate state, we use a bound level on the metastable $^{1}S_{0}\text{\ensuremath{-}}^{3}P_{1}$ potential, which provides large Franck-Condon transition factors and narrow one-photon photoassociative lines that are advantageous for observing quantum-optical effects such as Autler-Townes resonance splittings.
Abstract Using the quantum wave-packet method, we investigated the photoassociation (PA) processes of H + + He → HeH + in the ground electronic state (X 1 Σ g + ). Two cases are considered where the target vibrational state selected is v = 4 and 8, respectively. It is found (for the first time) that above-threshold dissociation (ATD) occurs alongside the PA process (PA-ATD). ATD dissociation can be the major loss mechanism for the PA process. Compared with the direct dissociation from a given vibrational state and continuum–continuum transitions to the same final energy, the overall PA-ATD process is enhanced in comparison to individual contributions due to correlations. The one-photon dissociation from the target vibrational state, the ATD signals from two-photon dissociation and the higher-order (three- and four-photon) dissociations are the results of different mechanisms.
We present the formation of homonuclear Cs_{2}, K_{2}, and heteronuclear CsK long-range Rydberg molecules in a dual-species magneto-optical trap for ^{39}K and ^{133}Cs by one-photon UV photoassociation. The different ground-state-density dependence of homo- and heteronuclear photoassociation rates and the detection of stable molecular ions resulting from autoionization provide an unambiguous assignment. We perform bound-bound millimeter-wave spectroscopy of long-range Rydberg molecules to access molecular states not accessible by one-photon photoassociation. Calculations based on the most recent theoretical model and atomic parameters do not reproduce the full set of data from homo- and heteronuclear long-range Rydberg molecules consistently. This shows that photoassociation and millimeter-wave spectroscopy of heteronuclear long-range Rydberg molecules provide a benchmark for the development of theoretical models.