Molecules of interest inside of the buffer-gas cell are probed using cavity-ringdown spectroscopy (CRDS). The optical cavity is 45 cm in length and formed using two highly reflective mirrors (LayerTec, 1550 nm, 99.995% reflective) in custom optical mounts secured directly to the six-way cross. The probe laser is a tunable external cavity diode laser (ECDL) with a linewidth < 10 kHz (Toptica CTL-1550). Laser light is scanned across the cavity and frequency measurements are made by sending the zeroth order beam from an acousto-optic modulator into a wavemeter (Bristol, 228B). The beam is coupled into the cavity using a pair of mode-matching lenses (f = 750, 250 mm) while one of the mirrors is continuously dithered by a cylindrical piezoelectric actuator. Ringdown events are collected using an InGaAs photodiode and recorded using custom software written in LabVIEW. 100 ringdown events are collected per frequency step (0.0004 cm -1 ) and fit to an exponential de-cay function. The absorption coefficient, α, is extracted from the collected ringdown times τ (ν) as a function of frequency ν via the following relation