The Boltzmann constant kB is a fundamental physical constant in thermodynamics. The present CODATA recommended value of kB is 1.3806488（13） × 10^-23 J/K （relative uncertainty 0.91 ppm）, which is mainly determ...The Boltzmann constant kB is a fundamental physical constant in thermodynamics. The present CODATA recommended value of kB is 1.3806488（13） × 10^-23 J/K （relative uncertainty 0.91 ppm）, which is mainly determined by acoustic methods. Doppler broadening thermometry （DBT） is an optical method which determines kBT by measuring the Doppler width of an atomic or molecular transition. The methodology and problems in DBT are reviewed, and DBT measurement using the sensitive cavity ring-down spectroscopy （CRDS） is proposed. Preliminary measurements indicate that CRDS- based DBT measurement can potentially reach an accuracy at the 1 ppm level.展开更多
As is always accompanying temperature in physics fundamental principles, Boltzmann constant kB can be used to verify the accuracy of a thermometer. This paper presents a photoluminescent method to measure kB via tempe...As is always accompanying temperature in physics fundamental principles, Boltzmann constant kB can be used to verify the accuracy of a thermometer. This paper presents a photoluminescent method to measure kB via temperature dependent fluorescence of phosphors. Diagram of a phosphor＇s energy levels was simplified to illustrate the principle of measurement. The relationship between kB and h＊c （Planck constant h multiplying light speed in vacuum c） was experimentally derived. Finally, the determined kB was 1.38065 x l0 23j/K. The determination could give a value of （1.38＋0.1） × 10 23 J/K even when the in-use spectrometer was with a poor resolution as about 2 nm. At the end, optimization of measuring conditions for the determination process was suggested.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.91436209,21225314,and 91221304)Chinese Academy of Sciences(Grant No.XDB01020000)
文摘The Boltzmann constant kB is a fundamental physical constant in thermodynamics. The present CODATA recommended value of kB is 1.3806488（13） × 10^-23 J/K （relative uncertainty 0.91 ppm）, which is mainly determined by acoustic methods. Doppler broadening thermometry （DBT） is an optical method which determines kBT by measuring the Doppler width of an atomic or molecular transition. The methodology and problems in DBT are reviewed, and DBT measurement using the sensitive cavity ring-down spectroscopy （CRDS） is proposed. Preliminary measurements indicate that CRDS- based DBT measurement can potentially reach an accuracy at the 1 ppm level.
基金Acknowledgements This work was jointly supported by the National Natural Science Foundation of China （Grant No. 61167007） and the Foundation of Aeronautics （No. 2012ZD56007）.
文摘As is always accompanying temperature in physics fundamental principles, Boltzmann constant kB can be used to verify the accuracy of a thermometer. This paper presents a photoluminescent method to measure kB via temperature dependent fluorescence of phosphors. Diagram of a phosphor＇s energy levels was simplified to illustrate the principle of measurement. The relationship between kB and h＊c （Planck constant h multiplying light speed in vacuum c） was experimentally derived. Finally, the determined kB was 1.38065 x l0 23j/K. The determination could give a value of （1.38＋0.1） × 10 23 J/K even when the in-use spectrometer was with a poor resolution as about 2 nm. At the end, optimization of measuring conditions for the determination process was suggested.
