Doppler broadening thermometry based on cavity ring-down spectroscopy

Abstract

A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach a satisfied precision at lower sample pressures, which also reduces the influence due to collisions. By recording the spectrum of C${}_2$H${}_2$ at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. The influence on the spectroscopy-determined temperatures has been investigated, including the "hidden" weak lines overlapped with the selected transition for DBT measurements. The reproducibility has also been examined to be better than 10 ppm, and it indicates that the instrument is feasible for DBT measurement toward a precision at the ppm level.

9 pages, 8 figures

References in corpus (4)

• CODATA Recommended Values of the Fundamental Physical Constants: 2010
• Primary gas thermometry by means of laser-absorption spectroscopy: Determination of the Boltzmann constant
• Evidence for speed-dependent effects in NH3 self-broadened spectra: towards a new determination of the Boltzmann constant
• Absorption line shape recovery beyond the detection bandwidth limit: application to the precision spectroscopic measurement of the Boltzmann constant

Cited by in corpus (1)

• Molecular near-infrared transitions determined with sub-kHz accuracy