A new approach to removing interference of moisture from FTIR spectrum

Xiaohua Zhang; Anqi He; Ran Guo; Ying Zhao; Limin Yang; Shigeaki Morita; Yizhuang Xu; Isao Noda; Yukihiro Ozaki

doi:10.1016/j.saa.2021.120373

A new approach to removing interference of moisture from FTIR spectrum

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Jan 15:265:120373. doi: 10.1016/j.saa.2021.120373. Epub 2021 Sep 15.

Authors

Xiaohua Zhang¹, Anqi He², Ran Guo³, Ying Zhao⁴, Limin Yang⁵, Shigeaki Morita⁶, Yizhuang Xu⁷, Isao Noda⁸, Yukihiro Ozaki⁹

Affiliations

¹ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
² Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, PR China.
³ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Beijing CKC, PerkinElmer Inc., Beijing 100015, PR China.
⁴ Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
⁵ State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, PR China. Electronic address: yanglm@pku.edu.cn.
⁶ Department of Engineering Science, Osaka Electro-Communication University, Osaka 572-8530, Japan.
⁷ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Jiangsu JITRI Molecular Engineering Inst. Co., Ltd., Suzhou, Jiangsu 215500, PR China. Electronic address: xyz@pku.edu.cn.
⁸ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, United States.
⁹ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; School of Biological and Environmental Sciences and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan.

PMID: 34547685
DOI: 10.1016/j.saa.2021.120373

Abstract

An approach is developed to remove the interference of moisture from FTIR spectra. The interference arises from two aspects: the fluctuation on the temperature of the HeNe laser and the fluctuation on the transient concentration of moisture in the light - path of an FTIR spectrometer. The temperature fluctuation on the HeNe laser produces a systematic spectral shift between single-beam sample and background spectra, which often makes spectral subtraction method invalid in removing the interference of moisture. Herein, the Carbo similarity metric (the C_AB value) is used to reflect the subtle spectral shift. A database of single-beam background spectra is established based on the concept of big-data and the pigeon-hole theory. The spectral shift is corrected by selecting suitable single-beam background spectra from the database to match with the given single-beam sample spectrum according to the C_AB value. The interference caused by the fluctuation of the transient concentration of moisture is removed using a comprehensive 2D-COS method. We apply the approach on two polymeric samples to retrieve high-quality spectra and reliable second derivative spectra without the interference of moisture. The present work provides a new opportunity of obtaining the reliable second derivative spectra in the spectral region masked by moisture.

Keywords: 2D-COS; Big-data; FTIR; SACPs; Water vapor.