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Title: Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy

Abstract

The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as 'fingerprints' to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient–mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithmmore » of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.« less

Authors:
;  [1]; ;  [2];  [3]
  1. Institute of Fluid Flow and Heat Transfer and IGCIT Beijing University of Chemical Technology (China)
  2. National Institute of Metrology, Optics Division (China)
  3. Qingdao University of Science and Technology (China)
Publication Date:
OSTI Identifier:
22810121
Resource Type:
Journal Article
Journal Name:
Journal of Applied Spectroscopy
Additional Journal Information:
Journal Volume: 85; Journal Issue: 1; Other Information: Copyright (c) 2018 Springer Science+Business Media, LLC, part of Springer Nature; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9037
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; AIR; ALDEHYDES; BACKGROUND NOISE; CONCENTRATION RATIO; FOURIER TRANSFORMATION; HUMIDITY; REFRACTIVE INDEX; WATER VAPOR

Citation Formats

Zhang, J., E-mail: zhangjw@mail.buct.edu.cn, Xia, T., Chen, Q., Sun, Q., Deng, Y., and Wang, C.. Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy. United States: N. p., 2018. Web. doi:10.1007/S10812-018-0616-6.
Zhang, J., E-mail: zhangjw@mail.buct.edu.cn, Xia, T., Chen, Q., Sun, Q., Deng, Y., & Wang, C.. Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy. United States. https://doi.org/10.1007/S10812-018-0616-6
Zhang, J., E-mail: zhangjw@mail.buct.edu.cn, Xia, T., Chen, Q., Sun, Q., Deng, Y., and Wang, C.. 2018. "Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy". United States. https://doi.org/10.1007/S10812-018-0616-6.
@article{osti_22810121,
title = {Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy},
author = {Zhang, J., E-mail: zhangjw@mail.buct.edu.cn and Xia, T. and Chen, Q. and Sun, Q. and Deng, Y. and Wang, C.},
abstractNote = {The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as 'fingerprints' to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient–mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.},
doi = {10.1007/S10812-018-0616-6},
url = {https://www.osti.gov/biblio/22810121}, journal = {Journal of Applied Spectroscopy},
issn = {0021-9037},
number = 1,
volume = 85,
place = {United States},
year = {2018},
month = {3}
}