Absolute frequency metrology of buffer-gas-cooled molecular spectra at 1 kHz accuracy level

Abstract

By reducing both the internal and translational temperature of any species down to a few kelvins, the buffer-gas-cooling (BGC) technique has the potential to dramatically improve the quality of ro-vibrational molecular spectra, thus offering unique opportunities for transition frequency measurements with unprecedented accuracy. However, the difficulty in integrating metrological-grade spectroscopic tools into bulky cryogenic equipment has hitherto prevented from approaching the kHz level even in the best cases. Here, we overcome this drawback by an original opto-mechanical scheme which, effectively coupling a Lamb-dip saturated-absorption cavity ring-down spectrometer to a BGC source, allows us to determine the absolute frequency of the acetylene (ν1 + ν3) R(1)e transition at 6561.0941 cm−1 with a fractional uncertainty as low as 6 × 10−12. By improving the previous record with buffer-gas-cooled molecules by one order of magnitude, our approach paves the way for a number of ultra-precise low-temperature spectroscopic studies, aimed at both fundamental Physics tests and optimized laser cooling strategies.

Lamb-dip ro-vibrational spectroscopy of buffer-gas-cooled acetylene

“…Then, in order to minimize the detrimental effects of the vibrations from the PT on the HFC components, we act on two fronts [17].…”

Doppler-free Spectroscopy of Buffer-Gas-Cooled Calcium Monohydroxide

“…Slow beam velocities in the laboratory frame and a wide applicable temperature range are important characteristics of buffer gas cooling. Currently, numerous spectroscopic studies using buffer gas cooling have been reported. − …”

“…Using saturation effects to cancel the Doppler widths and shifts, we can resolve them and determine the transition frequency with an uncertainty of 10 MHz, which is three times smaller than that of the previous study. There have been some reports on Doppler-free spectroscopy of molecules cooled by a buffer gas. ,,, However, these studies have mainly focused on stable molecules or diatomic radicals. This study demonstrates that buffer-gas-cooled Doppler-free spectroscopy is possible for polyatomic radicals with an uncertainty of 10 MHz with a simple extension of a usual absorption measurement setup in the buffer gas cell.…”

“…There have been some reports on Doppler-free spectroscopy of molecules cooled by a buffer gas. 22,25,27,29 However, these studies have mainly focused on stable molecules or diatomic radicals. This study demonstrates that buffer-gas-cooled Doppler-free spectroscopy is possible for polyatomic radicals with an uncertainty of 10 MHz with a simple extension of a usual absorption measurement setup in the buffer gas cell.…”

On the 12C2H2 near-infrared spectrum: absolute transition frequencies and an improved spectroscopic network at the kHz accuracy level

“…16,17 A considerable number of transitions have been measured for acetylene isotopologues with close to kHz accuracy. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] In this regard, the comprehensive study of ref. 1 concerning the experimental spectroscopic measurements on the parent isotopologue, 12 C 2 H 2 , should be considered incomplete: at the time the MARVEL dataset was assembled, results from several important precision-spectroscopy studies were simply not available and a few existing ones were not utilized to their full extent.…”