Primary thermometry from a CO2 overtone line via comb-assisted cavity-ring-down spectroscopy

Gotti, Riccardo

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https://hdl.handle.net/2142/100454 Copy

Description

Title

Primary thermometry from a CO2 overtone line via comb-assisted cavity-ring-down spectroscopy

Author(s)

Gotti, Riccardo

Contributor(s)

• Marangoni, Marco
• Gianfrani, Livio
• Laporta, Paolo
• Galzerano, Gianluca
• Castrillo, Antonio
• Gatti, Davide
• Moretti, Luigi

Issue Date

2018-06-20

Keyword(s)

Mini-symposium: Frequency-Comb Spectroscopy

Abstract

We provide the most accurate absolute temperature measurement ever performed on an atomic or molecular sample with a Doppler-Broadening-Thermometry approach. Specifically, the absorption profile of the Pe(12) line of the (30012) - (00001) band of a CO2 sample at thermodynamic equilibrium is accurately measured at 1.578 µm by a comb-assisted cavity-ring-down spectrometer that combines an extremely dense frequency axis (3000 points over 4.2 GHz) with an acquisition time as low as a few seconds. The Doppler width is extracted from a refined multi-spectrum 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 rank the system at the first place among optical methods. Thanks to a measurement time of only 5 h, the technique represents a promising pathway towards the optical determination of the thermodynamic temperature with a global uncertainty at the 10−6 level a . An additional element of interest derives from the forthcoming redefinition of the unit Kelvin b , in 2018, which calls for primary thermometers that are capable to operate over a large part of the temperature scale with very high accuracy.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100454

DOI

10.15278/isms.2018.WG05

Copyright and License Information

Copyright 2018 Riccardo Gotti

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