Abstract：Water vapor absorption, which exists in mid-infrared region, is an interferential element for infrared spectra analysis. A new method, which can be used to eliminate the water vapor interference in FTIR measurement, is presented. To calculate the high resolution absorbance of water vapor, a fast line by line method which computed with the HITRAN database (eg. line strength, self broadening, air broadening, etc) and meteorological parameters (eg. temperature, pressure, and relative humidity) was used. After convolving with Instrumental line shape (eg. divergence angle, resolution, etc), the absorbance of water vapor was then transferred from high resolution to low resolution, which matched the instrumental parameters. After the acquirement of water vapor absorbance spectrum, it will be subtracted from the measured spectrum to calculate the spectrum with the water vapor was eliminated. In the present work, analysis of measured data from open path FTIR is described. Only the absorbing character and noise was left in the spectrum after eliminating the water vapor interference. Consequently, this method has an ideal effect on water vapor elimination when there is no dryer can be used, especially in the case of open path FTIR measurement.
Key words：Open path;FTIR;Water vapor;Instrumental line shape;Elimination
徐亮,刘建国,高闽光,陆亦怀,刘文清,魏秀丽,张天舒,陈华,刘志明. 基于仪器线型订正的开放光程FTIR测量中的水汽谱在线扣除方法[J]. 光谱学与光谱分析, 2008, 28(05): 1052-1056.
XU Liang,LIU Jian-guo,GAO Min-guang,LU Yi-huai,LIU Wen-qing,WEI Xiu-li,ZHANG Tian-shu,CHEN Hua,LIU Zhi-ming. A Method of Eliminating the Water Vapor Interference Simultaneously in Open Path FTIR Measurement by Instrumental Line Shape Correction. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2008, 28(05): 1052-1056.
[1] HUANG Zhong-hua, WANG Jun-de（黄中华，王俊德）. Spectroscopy and Spectral Analysis（光谱学与光谱分析）, 2002, 22(2): 235. [2] Lee B. J. Air Waste Manag. Assoc., 1991, 41: 16. [3] Shcaefer K, Haus R, Heland J, et al. J. Phys. Chem. , 1995, 99(3): 405. [4] Griffith D W T, Galle Bo. Atmos. Environ., 2000, 34: 1087. [5] Todd L A. Appl. Occup. Environ. Hyg.，1996, 11: 1327. [6] Griffiths Peter R, Haseth de J. Fourier Transform Infrared Spectroscopy. New York: Wiley & Sons, 1986. [7] Anderson Robert J, Griffiths Peter R. Analytical Chemistry, 1975，47(14): 2339. [8] David W T Griffith. Appl. Spectrosc., 1996, 50: 59. [9] Jacquinet-Husson N, Arie E, Ballard J, et al. J. Quant. Spectrosc. Radiat. Transfer，1999, 62(2): 205. [10] Mankin William G. Applied Optics，1999，18(20): 3426. [11] ZHANG Hua, SHI Guang-yu(张 华，石广玉). Chinese Journal of Atmospheric Sciences(大气科学), 2000, 24(1): 111. [12] Press W H, Teukolsky S A, Vetterling W T, et al. Translated by HU Jian-wei, ZHAO Zhi-yong, XUE Yun-hua(胡健伟，赵志勇，薛运华译). Numerical Recipes in C++: The Art of Scientific Computing(C++数值算法). Beijing: Publishing House of Electronics Industry(北京：电子工业出版社), 2005. 504. [13] XU Liang, LIU Jian-guo, GAO Min-guang, et al（徐 亮，刘建国，高闽光，等）. Spectroscopy and Spectral Analysis（光谱学与光谱分析）, 2007，27(3)：448.
