Li Linying, Zhao Huan, Ni Nan, Wang Yongda, Gao Jie, Gao Qiang, Zhang Yucun, Zhang Yungang
School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, PR China.
School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150080, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Jul 5;275:121192. doi: 10.1016/j.saa.2022.121192. Epub 2022 Mar 25.
In accordance with the Beer-Lambert law, absorbance is proportional to concentration and optical path length of the absorbers in the sample, and in a linear relationship with total column concentration (product of concentration and optical path length) at a single wavelength. However, limitation of spectral resolution will result in linear deviation with the Beer-Lambert law in actual measurement. Regarding additivity of polychromatic light intensity as the theoretical basis, this paper attributed linear deviation with the Beer-Lambert law to spectral resolution, concentration and light intensity, and verified this explanation by measuring sulfur dioxide at various total column concentrations using spectrometers with different spectral resolutions in the waveband range of 216-230 nm. It was found that linear deviation with the Beer-Lambert law was in negative correlation with spectral resolution, and in positive correlation with total column concentration, and absorbance could be considered to be linear with total column concentration (below 171.4 mg/m) of sulfur dioxide in the wavelength range of 216-230 nm. In addition, it was also proved that linear deviation increases with decreasing light intensity at a fixed sulfur dioxide column concentration.
根据比尔-朗伯定律，吸光度与样品中吸收体的浓度和光程长度成正比，并且在单一波长下与总柱浓度（浓度与光程长度的乘积）呈线性关系。然而，光谱分辨率的限制会导致实际测量中与比尔-朗伯定律产生线性偏差。本文以多色光强度的加和性为理论基础，将与比尔-朗伯定律的线性偏差归因于光谱分辨率、浓度和光强，并通过在216 - 230 nm波段范围内使用具有不同光谱分辨率的光谱仪测量不同总柱浓度下的二氧化硫来验证这一解释。研究发现，与比尔-朗伯定律的线性偏差与光谱分辨率呈负相关，与总柱浓度呈正相关，并且在216 - 230 nm波长范围内，二氧化硫的吸光度在总柱浓度低于171.4 mg/m时可被认为与总柱浓度呈线性关系。此外，还证明了在固定的二氧化硫柱浓度下，线性偏差随光强降低而增大。
