Doppler-width thermodynamic thermometry by means of line-absorbance analysis

A clean and effective implementation of Doppler-width thermometry is described. Exploiting the relationship between line-center absorbance and integrated absorbance, the Doppler width of a molecular spectral line can be retrieved from a set of profiles resulting from different gas pressures. The method is validated by its application to numerically simulated spectra. Preliminary experiments, in water vapor samples, turn out to be successful, demonstrating Doppler-widths' retrieval in the near-infrared with a precision of 8 x 10(-5), at the water triple point temperature. The direct link to the Boltzmann constant makes the proposed method very attractive for temperature metrology as a tool for the realization of a new thermodynamic temperature scale.