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

• Published in: arXiv.org 2018-10
• Main Authors: Reschovsky, B J, Ruzic, B P, Miyake, H, Pisenti, N C, Julienne, P S, Campbell, G K
• Format: Article
• Language: English
• Subjects: Binding energy; Dimers; Mathematical models; Scaling; Strontium
• ISSN: 2331-8422

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 \(^1\mathrm{S}_0 + \phantom{ }^3\mathrm{P}_1\) \(0_u^+\) \((^3\Pi_u)\) and \(^1\mathrm{S}_0 + \phantom{ }^1\mathrm{D}_2\) \(0_u^+\) \((^1\Sigma_u^+)\) 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 \(0_u^+,\ \nu=-2\) to \(\nu=-5\) states are measured and compared to numerical estimates to characterize their use as optical Feshbach resonances.