We present results which probe the structure of
85Rb2 very near its lowest dissociation limit. To obtain these results, we used two different variations of photoassociation spectroscopy of laser-cooled and trapped
85Rb atoms. First, we have determined the positions of twelve of the highest vibrational levels of
85Rb2, all bound by less than
0.7cm−1, with two-color (free-bound-bound) photoassociation spectroscopy. The levels lie in an energy range for which singlet and triplet states are strongly mixed by the hyperfine interaction. We found that we could accurately describe these states with a novel coupled-channels inverse perturbation analysis. In a second experiment, we have carried out Zeeman-resolved photoassociation spectroscopy. This technique allowed us to probe the energy range in the lowest part of the electronic ground state continuum, which lies between the dissociation limits corresponding to different hyperfine states of the separated atoms. With this method, we have observed a Feshbach scattering resonance in the continuum for the first time, which we find can be tuned to zero energy with a magnetic field.
We have observed the spectrum of long range molecular states of singly excited
Na2 formed by photoassociation during ultracold associative ionization collisions of laser-cooled Na atoms. The low kinetic energy of the collision allows us to obtain very high resolution spectra and to observe states close to the dissociation limit. The spectrum shows regular vibrational series characteristic of the 1/
R3 long range portion of the
1g potential (asymptotically
S1/2+
P3/2) as well as molecular hyperfine structure within these peaks. We extract potential parameters and compare with recent theory.
Photoassociation of cold
87Rb(5s,fb=2) atom pairs is studied within 13 GHz of the dissociation limits
87Rb(5p3/2,fa)+87Rb(5s,fb=2). Vibrational levels in the long range, hyperfine manifolds of the ${0}_{g}^{\ensuremath{-}}$ and
1g states arising from the
87Rb(5p3/2) fine structure limit are identified to lead to the formation of stable molecules in the photoassociation process. The vibrational bands are observed to break off, at positions matching the energetic location of potential-energy barriers predicted in the hyperfine manifolds at about 1 GHz above the
87Rb(5p3/2,fa=3)+87Rb(5s,fb=1) dissociation limit. Empiricial potential-energy curves are derived from the data. These are found to be in agreement with predictions based on the long-range hyperfine recoupling of the excited molecular states. The selectivity of the excitation process and predissociation mechanisms are discussed.
We report the high resolution photoassociation (PA) spectroscopy of a
87Rb Bose-Einstein condensate (BEC) to excited molecular states near the dissociation limit of
5P1/2+5S1/2 by optical Bragg scattering. Since the detection of optical Bragg scattering in BEC has a high signal-noise ratio, we obtain the high resolution PA spectrum of excited molecular states in the range of
±1 GHz near the dissociation limit of
5P1/2+5S1/2. We compare the results with the conventional method of trap loss and show that the results agree each other very well. Many interesting phenomena of excited molecular states are observed, such as light-induced frequency shift and the anomalous strong bound molecular lines at the atomic transition from
∣F=1⟩ to
∣F′=2⟩. The observed excited molecular states in the range of
±1 GHz near the dissociation limit of
5P1/2+5S1/2 are never reported before, which will help to further improve the long range bound state models near the dissociation limit.
We report the high-resolution photoassociation (PA) spectroscopy of a
87Rb Bose-Einstein condensate (BEC) to excited molecular states near the dissociation limit of
5P1/2+5S1/2 by optical Bragg scattering. Since the detection of optical Bragg scattering in the BEC has a high signal-noise ratio, we obtain the high-resolution PA spectrum of excited molecular states in the range of $\ifmmode\pm\else\textpm\fi{}1$ GHz near the dissociation limit of
5P1/2+5S1/2. We compare the results with the conventional method of trap loss and show that the results agree with each other very well. Many interesting phenomena of excited molecular states are observed, such as light-induced frequency shift and anomalous strong bound molecular lines at the atomic transition from $|F=1\ensuremath{\rangle}$ to $|{F}^{\ensuremath{'}}=2\ensuremath{\rangle}$. The observed excited molecular states in the range of $\ifmmode\pm\else\textpm\fi{}1$ GHz near the dissociation limit of
5P1/2+5S1/2 should help to further improve long-range bound-state models near the dissociation limit.
We present analysis of low-
n long-range molecular Rydberg states in
85Rb
2, based on high-resolution spectra. The weakly bound states are accessed by bound-bound transitions from high-
v levels of the
a,3Sigmau+ state, which are prepared by photoassociation of laser-cooled atoms. Single-photon transitions to target states near the
5s+7p asymptote are excited by a frequency-doubled pulse-amplified CW laser with a narrow linewidth, under 200 MHz. The long-range portion of the bonding potential is dominated by the elastic scattering interaction of the Rydberg electron of a perturbed
7p atom and a nearby ground-state atom, in much the same manner as trilobite states. We use time of flight to selectively measure molecular ions, which are formed via autoionization. This technique gives a two orders-of-magnitude improvement in linewidth over our previous work, reported in Ref. [1]. We also present calculations of a proposed scheme for STIRAP transfer from the current
v′′=35 level of the
a,3Sigmau+ state to the
v′′=39 level. The long-range states accessible to us are defined in large part by the Franck-Condon factors, which are dominated by the outer lobe of the wavefunction. Thus, choosing a
v′′ sets
R, and determines the Franck-Condon window. The proposed
v′′=39 level has a classical outer turning point at
sim72,a0, and will provide access to higher-
n states with longer-range wells. This work is supported by the NSF and AFOSR.\ noindent [1] M. A. Bellos textit{et al.}, Phys. Rev. Lett. textbf{111}, 053001 (2013)