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Journal of Spectroscopy
Volume 2014 (2014), Article ID 732802, 9 pages
http://dx.doi.org/10.1155/2014/732802
Research Article

Terahertz Absorption Spectroscopy of Benzamide, Acrylamide, Caprolactam, Salicylamide, and Sulfanilamide in the Solid State

1College of Pharmacy, Liaoning University of Traditional Chinese Medicine, Dalian 116600, China
2School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China
3State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
4Department of Physics, Capital Normal University, Beijing 100037, China
5The State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China

Received 6 September 2013; Accepted 14 December 2013; Published 16 February 2014

Academic Editor: Yizhuang Xu

Copyright © 2014 Ye Jiang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Terahertz (THz) absorption spectra of the similarly structured molecules with amide groups including benzamide, acrylamide, caprolactam, salicylamide, and sulfanilamide in the solid phase at room temperature and 7.8 K for salicylamide are reported and compared to infrared vibrational spectral calculations using density functional theory. The results of THz absorption spectra show that the molecules have characteristic bands in the region of 0.2–2.6 THz (~7–87 cm−1). THz technique can be used to distinguish different molecules with amide groups. In the THz region benzamide has three bands at 0.83, 1.63, and 1.73 THz; the bands are located at 1.44 and 2.00 THz for acrylamide; the bands at 1.24, 1.66 and 2.12 THz are observed for caprolactam. The absorption bands are located at 1.44, 1.63, and 2.39 THz at room temperature, and at 1.22, 1.46, 1.66, and 2.41 THz at low temperature for salicylamide. The bands at 1.63, 1.78, 2.00, and 2.20 THz appear for sulfanilamide. These bands in the THz region may be related to torsion, rocking, wagging, and other modes of different groups in the molecules.