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 K. Tokunaga; Christian J. Bordé; Christian Chardonnet; Christophe Daussy

doi:10.1051/epjconf/20135702005

All issues

Volume 57 (2013)

EPJ Web of Conferences, 57 (2013) 02005

Abstract

Open Access

Issue		EPJ Web of Conferences Volume 57, 2013 ICAP 2012 – 23^rd International Conference on Atomic Physics


Article Number		02005
Number of page(s)		11
Section		Fundamental atomic tests and precision measurements
DOI		https://doi.org/10.1051/epjconf/20135702005
Published online		30 August 2013

EPJ Web of Conferences 57, 02005 (2013)
https://doi.org/10.1051/epjconf/20135702005

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

Benoît Darquié¹^,2^a, Sinda Mejri²^,1, Papa Lat Tabara Sow¹^,2, Cyril Lemarchand²^,1^,b, Meriam Triki²^,1, Sean K. Tokunaga²^,1, Christian J. Bordé¹^,2^,3, Christian Chardonnet¹^,2 and Christophe Daussy²^,1

¹ CNRS, UMR 7538, LPL, 93430 Villetaneuse, France
² Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, 93430 Villetaneuse, France
³ Laboratoire National de Métrologie et d'Essais-Système de Références Temps-Espace, UMR 8630 Observatoire de Paris, CNRS, UPMC, 75014 Paris, France

^a e-mail: benoit.darquie@univ-paris13.fr

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 μm 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.

^b

Present address: Université Paul Sabatier, Université de Toulouse, LCAR, 31062 Toulouse, France

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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