NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Thermodynamic-Temperature Determinations of the Ag and Au Freezing Temperatures Using a Detector-Based Radiation Thermometer
Published
Author(s)
Howard W. Yoon, David W. Allen, Charles E. Gibson, Maritoni A. Litorja, Robert D. Saunders, Steven W. Brown, George P. Eppeldauer, Keith R. Lykke
Abstract
We describe the development of a radiation thermometer calibrated for spectral radiance responsivity using cryogenic, electrical-substitution radiometry to determine the thermodynamic temperatures of the Ag- and Au-freezing temperatures. The absolute spectral radiance responsivity of the radiation thermometer is measured in the NIST Spectral Irradiance and Radiance responsivity Calibrations using Uniform Sources (SIRCUS) facility with a total uncertainty of 0.15 % (k = 2) and is traceable to the electrical watt, and thus, the thermodynamic temperature of any blackbody can determined using Planck radiation law and the measured optical power. The thermodynamic temperatures of the Ag- and Au-freezing temperatures are determined to be 1234.956 K ( 0.110 K) (k = 2) and 1337.344 K ( 0.129 K) (k = 2) differing from the ITS-90 assignments by 26 mK and 14 mK, respectively. The temperatures were systematically corrected for the size-of-source effect, the linearity of the pre-amplifier and the emissivity of the blackbody. The temperatures are in agreement with the ITS-90 assigned values within the combined uncertainties. The ultimate goal of these thermodynamic temperature measurements is to disseminate temperature scales with lower uncertainties than the ITS-90. These results indicate that direct disseminations of thermodynamic temperature scales are possible.
blackbody radiation, freezing temperature, ITS-90, radiation thermometry, radiometry, thermodynamic temperature
Citation
Yoon, H.
, Allen, D.
, Gibson, C.
, Litorja, M.
, Saunders, R.
, Brown, S.
, Eppeldauer, G.
and Lykke, K.
(2007),
Thermodynamic-Temperature Determinations of the Ag and Au Freezing Temperatures Using a Detector-Based Radiation Thermometer, Applied Optics, [online], https://doi.org/10.1364/AO.46.002870
(Accessed October 9, 2025)