We have recorded the Doppler profile of a well-isolated rovibrational line in the \nu2 band of 14NH3. Ammonia gas was placed in an absorption cell thermalized by a water-ice bath. By extrapolating to zero pressure, we have deduced the Doppler width which gives a first measurement of the Boltzmann constant, kB, by laser spectroscopy. A relative uncertainty of 2x10-4 has been obtained. The present determination should be significantly improved in the near future and contribute to a new definition of the kelvin.
Cite
@article{arxiv.quant-ph/0701176,
title = {First direct determination of the Boltzmann constant by an optical method},
author = {Christophe Daussy and Mickael Guinet and Anne Amy-Klein and Khelifa Djerroud and Yves Hermier and Stephan Briaudeau and Christian J. Bordé and Christian Chardonnet},
journal= {arXiv preprint arXiv:quant-ph/0701176},
year = {2016}
}