Measuring the Boltzmann constant by mid-infrared laser spectroscopy of ammonia
Résumé
We report on our ongoing effort to measure the Boltzmann constant, k B , using the Doppler broadening technique on ammonia. This paper presents some of the improvements made to the mid-infrared spectrometer including the use of a phase-stabilized quantum cascade laser, a lineshape analysis based on a refined physical model and an improved fitting program 2 increasing the confidence in our estimates of the relevant molecular parameters, and a first evaluation of the saturation parameter and its impact on the measurement of k B. A summary of the systematic effects contributing to the measurement is given and the optimal experimental conditions for mitigating those effects in order to reach a competitive measurement of k B at a part per million accuracy level are outlined.
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