Open AccessTheoretical and applied researches on measuring line width in wavelength modulation spectroscopy
Author(s) -
Shufeng Zhang,
Lan Li-Juan,
Yao Ding,
Jia Junwei,
Zhimin Peng
Publication year - 2015
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.64.053301
Subject(s) - harmonics , tunable diode laser absorption spectroscopy , line (geometry) , doppler effect , materials science , optics , measure (data warehouse) , spectroscopy , line width , absorption spectroscopy , absorbance , wavelength , modulation (music) , laser , physics , atomic physics , tunable laser , computer science , acoustics , geometry , mathematics , quantum mechanics , voltage , astronomy , database
Line width is the key parameter in tunable diode laser absorption spectroscopy (TDLAS); the dominant line widths are Doppler and collisional broadenings. Under low absorbance, the ratios of 2nd to 4th harmonics at the line center monotonously decrease and intersect at a fixed point, regardless of the changes in Doppler and collisional line widths. Based on this characteristic, a method is proposed which employs the ratios to measure the line width. To validate the reliability and accuracy of the proposed method, the transition of CO2 at 6982.0678 cm-1 is selected to measure the line width, the gas partial and total pressure. Experimental results show that the proposed method can achieve high precision in actual measurements.