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Updated: May 11, 2026

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores
Published on: August 19, 2013
[Study on THz spectra and vibrational modes of benzoic acid and sodium Benzoate]
Zhuan-Ping Zheng1, Wen-Hui Fan, Hui Yan
1State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China. zzp@opt.cn
Abstract:
Terahertz time-domain spectroscopy was employed to measure the terahertz absorption spectra of benzoic acid and sodium benzoate at room temperature. The origins of the measured features of benzoic acid were summarized based on previous study. Density functional theory was used to compute and analyze the molecular structure and vibrational modes of sodium benzoate in monomer. Based on the obtained results, the authors found that the THz spectral features can be used to distinguish benzoic acid and sodium benzoate totally; the essential reason for the THz spectral difference between benzoic acid and sodium benzoate is that the electrovalent bond of sodium benzoate affects the values of covalent bond lengths and bond angles, as well as the molecular interactions and arrangement in unit cell; the measured features of benzoic acid and sodium benzoate come from the collective vibrations except the peaks located at 107 cm-1 of benzoic acid and 54 cm-1 of sodium benzoate.
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