Cavity-ring-down Doppler-broadening primary thermometry

Riccardo Gotti, Luigi Moretti, Davide Gatti, Antonio Castrillo, Gianluca Galzerano, Paolo Laporta, Livio Gianfrani, Marco Marangoni
2018 Physical Review A  
A step forward in Doppler-broadening thermometry is demonstrated using a comb-assisted cavity-ring-down spectroscopic approach applied to an isolated near-infrared line of carbon dioxide at thermodynamic equilibrium. Specifically, the line-shape of the P e (12) line of the (30012) ← (00001) band of CO 2 at 1.578 µm is accurately measured and its Doppler width extracted from a refined multispectrum fitting procedure accounting for the speed dependence of the relaxation rates, which were found to
more » ... which were found to play a role even at the very low pressures explored, from 1 to 7 Pa. The thermodynamic gas temperature is retrieved with relative uncertainties of 8 × 10 −6 (type A) and 11 × 10 −6 (type B), which ranks the system at the first place among optical methods. Thanks to a measurement time of only ≈5 h, the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10 −6 level.
doi:10.1103/physreva.97.012512 fatcat:kcchqvqjy5htldze3yaral6qtm