Buffer-gas cooling of hydrogen cyanide quantified by cavity-ringdown spectroscopy

Abstract

We describe an instrument that uses continuous-wave (CW) cavity-ringdown spectroscopy to measure the translational and rotational temperature of buffer-gas cooled molecules and demonstrate its use on hydrogen cyanide. This instrument can access the near-infrared region around 1.5 μm—a rich spectral region that features the rotationally resolved first overtone of the C-H stretch for many astrophysically relevant molecules. Molecules are probed directly inside the buffer-gas cell, further enabling quantitative measurements of the effectiveness of this cooling technique.