High-Resolution Spectroscopy of Long-Range Rydberg Molecular States of $^{85}$Rb$_2$ Near the $5s+7p$ Asymptote

Long-range Rydberg molecules, often exemplified by trilobite molecules, are a subject of much recent interest at high principal quantum number $n$. We use a high-resolution pulsed amplifier to study previously-detected transitions to a low-$n$ Rydberg molecule state near the $5s+7p$ asymptote in $^{85}$Rb$_2$. The excited-state structure is modeled and a lower bound of $tau u003e 1.1 times 10^{-9}$ s is set on the autoionization lifetime.