Optical determination of the Boltzmann constant*
Cheng Cun-Feng, Sun Y. R., Hu Shui-Ming†
       
CRDS spectrum of the R (9) line of the ν 1 + 3 ν 3 band of C2H2. The sample pressure was 3.3 Pa. (a) Experimental (open circles) and simulated (solid line) spectra, panels (b)–(e) are fitting residules using different profiles: Gaussian, Voigt, and quadratic speed dependent Voigt (qSDVP), respectively.