Relative uncertainty of the determination can be estimated via:
where d
h/
h = 4.4 × 10
-8, and d
c/
c = 0 [
4]. Reading error of the energy gap and error of the fitting slope mainly decide the total uncertainty of final determination of
kB. The item d
s/
s can be lowered by a larger number of fitting points (temperature points) and accurate intensity monitoring. Then the left factor is the accuracy of the reading wavenumbers
v20 and
v10. That means that scanning repeatability and spectral resolution of the employed spectrometer is magnificently important for accurate/precise determination of the constant
kB. In our experiment, the spectrometer is a low resolution one, and then the determination uncertainty is not satisfactory enough. However, when supposing a spectrometer instead with a repeatability of 0.001 cm
-1 in the scanning range and resolution less than 0.1 cm
-1 at 550 nm, the relative uncertainty of the determination can be expected to be small as 1.3 × 10
-6, near the relative standard uncertainty of
kB (9.1 × 10
-7) from the CODATA [
4]. Experiments with higher spectral resolution and more accurate temperature control are under way.