In this paper we propose multispectrum rotational states distribution thermometry as an optical method for primary thermometry. It relies on a global fitting of multiple absorption lines of the same band at different pressures. The approach allows leveraging both the temperature-dependent Doppler width and the temperature-dependent distribution of line intensities across the ro-vibrational band. We provide a proof-of-principle demonstration of the approach on the 3ν 1 + ν 3 band of CO2, for which several accurate line-strength models of both theoretical and experimental origin are available for the global fitting. Our experimental conditions do not allow to test the methodology beyond a combined uncertainty of 530 ppm, but the comparative analysis between different line-strength models shows promise to reduce the error budget to few tens of ppm. As compared to Doppler-broadening thermometry, the approach is advantageous to mitigate systematic errors induced by a wrong modelling of absorption line-shapes and to reduce, for a given experimental dataset, the statistical uncertainty by a factor of 2. When applied in a reverse way, i.e. using a gas of known temperature, the approach becomes a stringent testbed for the accuracy of the adopted line-strength model.

Multispectrum rotational states distribution thermometry: Application to the 3ν 1+ ν 3band of carbon dioxide

Lamperti M.;
2020-01-01

Abstract

In this paper we propose multispectrum rotational states distribution thermometry as an optical method for primary thermometry. It relies on a global fitting of multiple absorption lines of the same band at different pressures. The approach allows leveraging both the temperature-dependent Doppler width and the temperature-dependent distribution of line intensities across the ro-vibrational band. We provide a proof-of-principle demonstration of the approach on the 3ν 1 + ν 3 band of CO2, for which several accurate line-strength models of both theoretical and experimental origin are available for the global fitting. Our experimental conditions do not allow to test the methodology beyond a combined uncertainty of 530 ppm, but the comparative analysis between different line-strength models shows promise to reduce the error budget to few tens of ppm. As compared to Doppler-broadening thermometry, the approach is advantageous to mitigate systematic errors induced by a wrong modelling of absorption line-shapes and to reduce, for a given experimental dataset, the statistical uncertainty by a factor of 2. When applied in a reverse way, i.e. using a gas of known temperature, the approach becomes a stringent testbed for the accuracy of the adopted line-strength model.
2020
frequency combs; molecular spectroscopy; primary thermometry
Gotti, R.; Lamperti, M.; Gatti, D.; Wojtewicz, S.; Puppe, T.; Mayzlin, Y.; Alsaif, B.; Robinson-Tait, J.; Rohde, F.; Wilk, R.; Leisching, P.; Kaenders, W. G.; Laporta, P.; Marangoni, M.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2136444
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