Determination of the Boltzmann constant by laser spectroscopy as a basis for future measurements of the thermodynamic temperature

Abstract

In this paper, we present the latest results on the measurement of the Boltzmann constant kB, by laser spectroscopy of ammonia at 10 ?m. The Doppler absorption profile of a ro-vibrational line of an NH3 gas sample at thermal and pressure equilibrium is measured as accurately as possible. The absorption cell is placed inside a large 1m3 thermostat filled with an ice-water mixture, which sets the temperature very close to 273.15 K. Analysing this profile, which is related to the Maxwell-Boltzmann molecular speed distribution, leads to a determination of the Boltzmann constant via a measurement of the Doppler width (proportional tosqrt(kBT)). A spectroscopic determination of the Boltzmann constant with an uncertainty as low as 37 ppm is obtained. Recent improvements with a new passive thermostat lead to a temperature accuracy, stability and homogeneity of the absorption cell better than 1 ppm over a day.

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Cited by in corpus (9)

• Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy
• A widely tunable 10-$\mu$m quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy
• Evidence for speed-dependent effects in NH3 self-broadened spectra: towards a new determination of the Boltzmann constant
• Measuring the Boltzmann constant by mid-infrared laser spectroscopy of ammonia
• A revised uncertainty budget for measuring the Boltzmann constant using the Doppler Broadening Technique on ammonia
• Absorption line shape recovery beyond the detection bandwidth limit: application to the precision spectroscopic measurement of the Boltzmann constant
• Spectral Lineshape Measurements with Shot-Noise Limited Accuracy
• Thermal Correction to the Molar Polarizability of a Boltzmann Gas
• Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin