Anomalies in the rotational spectra of ${}^{86}$Sr ULRRM dimers

Anomalies in the rotational structure of ${}^{86}$Sr ${}^3{S}_1$ dimer ultralong-range Rydberg molecules (ULRRMs) created in a cold strontium gas by two-photon excitation via the intermediate $5s5p{}^3{P}_1$ state are reported. Measurements reveal that the distribution of product rotational states is sensitive to intermediate state detuning. Comparative studies using ${}^{84}$Sr ${}^1{S}_0$ and ${}^3{S}_1$, and ${}^{86}$Sr ${}^1{S}_0$ dimers display no similar behavior, indicating that the observed behavior is peculiar to ${}^{86}$Sr triplet dimers. While we have no definitive hypothesis as to the physical mechanism responsible for this behavior, possible explanations might involve the very different scattering lengths for ${}^{84}$Sr and ${}^{86}$Sr, or the interchange of spin and rotational angular momentum.