The spectral characteristics of selected molecular sieves (3A, 4A, 5A, 13X and synthetic zeolite) in a terahertz (THz) range were studied by THz time-domain spectroscopy technologies (THz-TDS). The chemical composition of a molecular sieve is M_x/n[(AlO₂)x·(SiO₂)y]·zH₂O, where M is metal cation and n is the valence of the metal cation. The absorption coefficients and refractive indices were extracted in the spectra. Different from that of the A-type molecular sieves, the absorption curves and refractive indices of synthetic zeolite and 13X molecular sieve display large fluctuation as the frequency change. In addition, two kinds of related compounds (Al₂O₃ and quartz sand) were studied by using THz-TDS. The Al₂O₃ shows weak absorption and quartz sand has three typical absorption peaks at 0.89, 1.3, 1.55 THz. The refractive index of Al₂O₃ is kept at about 1.27 while that of quartz sand show large fluctuations. The present results suggested that the THz spectra of molecular sieves are in dependent of their types and indicated the potential of THz technology for the molecular sieve industry.

Date Published: 13 March 2012
PDF: 7 pages
Proc. SPIE 8330, Photonics and Optoelectronics Meetings (POEM) 2011: Laser and Terahertz Science and Technology, 833015 (13 March 2012); doi: 10.1117/12.919124

Published in SPIE Proceedings Vol. 8330:
Photonics and Optoelectronics Meetings (POEM) 2011: Laser and Terahertz Science and Technology
Jianquan Yao; X. C. Zhang; Dapeng Yan; Jinsong Liu, Editor(s)