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 Pe(12) line of the (30012)←(00001) band of CO2 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 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 ≈5h, the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10-6 level.

Cavity-ring-down Doppler-broadening primary thermometry

Gotti, Riccardo;Gatti, Davide;Galzerano, Gianluca;Laporta, Paolo;Marangoni, Marco
2018-01-01

Abstract

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 Pe(12) line of the (30012)←(00001) band of CO2 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 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 ≈5h, the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10-6 level.
2018
Atomic and Molecular Physics, and Optics
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1044972
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