Optical Path Length Calibration: A Standard Approach for Use in Absorption Cell-Based IR-Spectrometric Gas Analysis

Table 3

Uncertainty budget of 𝐿_gas for gas cell B (82 cm) derived by means of (2) with CH₄ being the probed sensor molecule. The index column is the relative contribution of the properties variance to the variance of 𝐿_gas [11].

Input quantity	Value	Relative uncertainty/%	Index/%
p	244 hPa	0.16	0.0
T	294.8 K	0.08	0.1
𝐴line	0.00402 cm^−1	0.4	0.6
𝑥species	0.01 mol/mol	0.99	3.7
𝑆0	8.289 × 10^−22; cm^−1/(cm^−2·molec)	5	95.4
𝐿gas	0.805 m	5