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arXiv · 1506.06464

Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

Benoît Darquié·Sinda Mejri·Papa Lat Tabara Sow·Cyril Lemarchand·Meriam Triki·Sean Tokunaga·Christian J. Bordé·Christian Chardonnet·Christophe Daussy
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Abstract

Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 $μ$m enables a determination of the Boltzmann constant k B. We report on our latest measurements. By fitting this lineshape to several models which include Dicke narrowing or speed-dependent collisional effects, we find that a determination of k B with an uncertainty of a few ppm is reachable. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of k B determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the kelvin by fixing k B, an exciting prospect considering the upcoming redefinition of the International System of Units.

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Benoît Darquié, Sinda Mejri, Papa Lat Tabara Sow, Cyril Lemarchand, Meriam Triki, Sean Tokunaga, Christian J. Bordé, Christian Chardonnet, Christophe Daussy. 2015-06-22. Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin. https://doi.org/10.1051/epjconf%2F20135702005

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