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arXiv:1808.06507

Narrow-line photoassociation spectroscopy and mass-scaling of bosonic strontium

Benjamin J. Reschovsky, Brandon Ruzic, Hirokazu Miyake, Neal C. Pisenti, Paul S. Julienne, Gretchen K. Campbell

Published Aug 20, 2018• 4 citations
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Abstract

Using new experimental measurements of photoassociation resonances near the $^1\mathrm{S}_0 \rightarrow \phantom{ }^3\mathrm{P}_1$ intercombination transition in $^{84}$Sr and $^{86}$Sr, we present an updated study into the mass-scaling behavior of bosonic strontium dimers. A previous mass-scaling model [Borkowski et al., Phys. Rev. A 90, 032713 (2014)] was able to incorporate a large number of photoassociation resonances for $^{88}$Sr, but at the time only a handful of resonances close to the dissociation limit were known for $^{84}$Sr and $^{86}$Sr. In this work, we perform a more thorough measurement of $^{84}$Sr and $^{86}$Sr bound states, identifying multiple new resonances at deeper binding energies out to $E/h=-5$ GHz. We also identify several previously measured resonances that cannot be experimentally reproduced and provide alternative binding energies instead. With this improved spectrum, we develop a mass-scaled model that reproduces the observed binding energies of $^{86}$Sr and $^{88}$Sr to within 1 MHz. In order to accurately reproduce the deeper bound states, our model includes a second $1_u$ channel and more faithfully reproduces the depth of the potential. As determined by the previous mass-scaling study, $^{84}$Sr $0_u^+$ levels are strongly perturbed by the avoided crossing between the $^1\mathrm{S}_0 + \phantom{ }^3\mathrm{P}_1$ $0_u^+$ $(^3Π_u)$ and $^1\mathrm{S}_0 + \phantom{ }^1\mathrm{D}_2$ $0_u^+$ $(^1Σ_u^+)$ potential curves and therefore are not included in this mass-scaled model, but are accurately reproduced using an isotope-specific model with slightly different quantum defect parameters. In addition, the optical lengths of the $^{84}$Sr $0_u^+,\ ν=-2$ to $ν=-5$ states are measured and compared to numerical estimates to characterize their use as optical Feshbach resonances.

DOI
10.48550/arxiv.1808.06507

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We report the use of photoassociative spectroscopy to determine the ground-state sss-wave scattering lengths for the main bosonic isotopes of strontium, 86Sr^{86}\mathrm{Sr}86Sr and 88Sr^{88}\mathrm{Sr}88Sr. Photoassociative transitions are driven with a laser red detuned by up to 1400 GHz from the $^{1}S_{0}\mathrm{\text{\ensuremath{-}}}^{1}P_{1}$ atomic resonance at 461 nm. A minimum in the transition amplitude for 86Sr^{86}\mathrm{Sr}86Sr at $\ensuremath{-}494\ifmmode\pm\else\textpm\fi{}5\text{ }\text{ }\mathrm{GHz}$ allows us to determine the scattering lengths 610a0<a86<2300a0610{a}_{0}<{a}_{86}<2300{a}_{0}610a0​<a86​<2300a0​ for 86Sr^{86}\mathrm{Sr}86Sr and a much smaller value of $\ensuremath{-}1{a}_{0}<{a}_{88}<13{a}_{0}$ for 88Sr^{88}\mathrm{Sr}88Sr.
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