Ma Jun, Duan Ning, Xu Fuyuan, Xiao Ke
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
Analyst. 2024 Aug 19;149(17):4425-4435. doi: 10.1039/d4an00400k.
In the analytical process of spectrophotometry, the prerequisite for accurate qualitative and quantitative analysis is obtaining the intrinsic spectra of the analyte. However, the intrinsic properties of spectra can sometimes be masked by easily overlooked non-intrinsic factors, such as those from measuring instruments, leading to erroneous spectral identification. In this study, we documented an unusual redshift phenomenon in the far ultraviolet spectral region. With a spectrophotometer under the nitrogen atmosphere, we selected 14 representative inorganic anions and investigated their absorption spectral behaviors at different optical pathlengths and concentrations. It was intriguing to observe that the absorption peaks with maximum absorption wavelengths below a watershed wavelength of 200 nm underwent a redshift as pathlength and concentration increased, while those above 200 nm did not exhibit a significant redshift phenomenon. In-depth formula simulations and experimental verifications demonstrated that this peculiar spectral behavior was caused by unavoidable stray light in the spectrophotometer. Some methodological and instrumental recommendations are given in the paper. Our study results may serve as a reminder to carefully identify non-intrinsic phenomena when studying absorption spectra in the far ultraviolet region, and provide guidance on spectral corrections in scientific research and practical applications.
在分光光度法的分析过程中，准确进行定性和定量分析的前提是获取分析物的本征光谱。然而，光谱的本征特性有时会被一些容易被忽视的非本征因素掩盖，比如来自测量仪器的因素，从而导致光谱识别错误。在本研究中，我们记录了远紫外光谱区域中一种不寻常的红移现象。在氮气气氛下，使用分光光度计，我们选择了14种具有代表性的无机阴离子，并研究了它们在不同光程长度和浓度下的吸收光谱行为。有趣的是，观察到最大吸收波长低于200nm分水岭波长的吸收峰随着光程长度和浓度的增加发生了红移，而那些高于200nm的吸收峰则没有表现出明显的红移现象。深入的公式模拟和实验验证表明，这种特殊的光谱行为是由分光光度计中不可避免的杂散光引起的。本文给出了一些方法和仪器方面的建议。我们的研究结果可能会提醒人们在研究远紫外区域的吸收光谱时要仔细识别非本征现象，并为科研和实际应用中的光谱校正提供指导。
