We study theoretically the properties of photoassociation spectra near the 1S0‐3P1 inter‐combination line of bosonic ytterbium. We construct a mass scaled model of the excited state interaction potential that well describes bound state energies obtained in a previous photoassociation experiment. We then use it to calculate theoretical photoassociation spectra in a range of ultracold temperatures using semianalytical theory developed by Bohn and Julienne.Photoassociation spectra not only give us the energies of excited bound states, but also provide information about the behavior of the ground state wavefunction. In fact, it can be shown that within the so‐called reflection approximation the line intensity is proportional to the ground state wavefunction at the transition’s Condon point. We show that in the case of ytterbium, the rotational structure of the photoassociation spectra depends heavily on the behavior of the ground‐state wavefunction. The change of the scattering length from one isotope to another and the resulting occurence of shape resonances in higher partial waves determines the appearance and disapperance of rotational components, especially in the deeper lying states, whose respective Condon points lie near the ground state centrifugal barrier. Thus, photoassociation spectra differ qualitatively between isotopes.
The properties of bosonic ytterbium photoassociation spectra near the intercombination transition ${^{1}S}_{0}\ensuremath{-}{^{3}P}_{1}$ are studied theoretically at ultralow temperatures. We demonstrate how the shapes and intensities of rotational components of optical Feshbach resonances are affected by mass tuning of the scattering properties of the two colliding ground-state atoms. Particular attention is given to the relationship between the magnitude of the scattering length and the occurrence of shape resonances in higher partial waves of the van der Waals system. We develop a mass-scaled model of the excited-state potential that represents the experimental data for different isotopes. The shape of the rotational photoassociation spectrum for various bosonic Yb isotopes can be qualitatively different.
The properties of photoassociation (PA) spectra near the intercombination line (the weak transition between and states) of group II atoms are theoretically investigated. As an example, we have carried out a calculation for calcium atoms colliding at ultralow temperatures of , , and . Unlike in most current photoassociation spectroscopy, the Doppler effect can significantly affect the shape of the investigated lines. Spectra are obtained using and short-range potentials and long-range van der Waals and resonance dipole potentials. The similar van der Waals coefficients of ground and excited states cause the PA to differ greatly from those of strong, allowed transitions with resonant dipole interactions. The density of spectral lines is lower, the Condon points are at relatively short range, the reflection approximation for the Franck-Condon factors is not applicable, and the spontaneous decay to bound ground-state molecules is efficient. Finally, the possibility of efficient production of cold molecules is discussed.
We observed high-resolution photoassociation spectra of laser-cooled ytterbium (Yb) atoms in the spin-forbidden 1S0 - 3P1 intercombination line. The rovibrational levels in the 0u+ state were measured for red detunings of the photoassociation laser ranging from 2.9 MHz to 1.97 GHz with respect to the atomic resonance. The rotational splitting of the vibrational levels near the dissociation limit were fully resolved due to the sub-MHz linewidth of the spectra in contrast to previous measurements using the spin-allowed singlet transition. In addition, from a comparison between the spectra of 174Yb and those of 176Yb, a d-wave shape resonance for 174Yb is strongly suggested.
We report observations of photoassociation (PA) spectra near the intercombination line in isotopic mixtures of ultracold ytterbium gases. Several heteronuclear bound states have been found for the excited
170Yb
174Yb and
174Yb
176Yb molecules. We develop a single-channel mass-scaled interaction model for the excited state molecule which well reproduces the measured bound state energies. This is an important step toward optical control of interactions in mixtures of ultracold ytterbium gases using heteronuclear optical Feshbach resonances. The model developed is applicable in collisions of other similar systems, such as cadmium and mercury.
We report photoassociation spectroscopy of ultracold
86Sr atoms near the intercombination line and provide theoretical models to describe the obtained bound-state energies. We show that using only the molecular states correlating with the
1S0+3P1 asymptote is insufficient to provide a mass-scaled theoretical model that would reproduce the bound-state energies for all isotopes investigated to date:
84Sr,86Sr, and
88Sr. We attribute that to the recently discovered avoided crossing between the
1S0+3P1 0u+ $({}^{3}{\ensuremath{\Pi}}_{u})$ and
1S0+1D2 0u+ $({}^{1}{\ensuremath{\Sigma}}_{u}^{+})$ potential curves at short range and we build a mass-scaled interaction model that quantitatively reproduces the available
0u+ and
1u bound-state energies for the three stable bosonic isotopes. We also provide isotope-specific two-channel models that incorporate the rotational (Coriolis) mixing between the
0u+ and
1u curves which, while not mass scaled, are capable of quantitatively describing the vibrational splittings observed in experiment. We find that the use of state-of-the-art ab initio potential curves significantly improves the quantitative description of the Coriolis mixing between the two $\ensuremath{-}8$-GHz bound states in
88Sr over the previously used model potentials. We show that one of the recently reported energy levels in
84Sr does not follow the long-range bound-state series and theorize on the possible causes. Finally, we give the Coriolis-mixing angles and linear Zeeman coefficients for all of the photoassociation lines. The long-range van der Waals coefficients
C6(0u+)=3868(50) a.u. and
C6(1u)=4085(50) a.u. are reported.
We report on the photoassociation (PA) spectroscopy of cold
171Yb atoms in a one-dimensional optical lattice. The PA spectral lines correlating to the
1S0+3P1 (f=1/2) state are observed experimentally. High accuracy and narrow atom-loss spectra are measured ranging up to about 1.2 GHz red detuning with respect to the atomic resonance. The main systematic frequency shifts of the PA transitions are determined with total uncertainties less than 100 kHz, which is more accurate than previous similar experimental results. We determine the initial scattering state of the PA spectra by comparing the spectra with polarized and unpolarized atomic samples. By comparatively analyzing theoretical results calculated based on an adiabatic molecular potential with experimental data, the excited molecular potentials corresponding to the spectral lines are clarified. The precision measurement of the narrow PA spectra plays an important role in exploring atomic interactions and lays the groundwork for the study of cold ytterbium molecules.