Find in Library
Search millions of books, articles, and more
Indexed Open Access Databases
Highly Sensitive, Calibration-Free WM-DAS Method for Recovering Absorbance—Part I: Theoretical Analysis
oleh: Zhimin Peng, Yanjun Du, Yanjun Ding
Format: | Article |
---|---|
Diterbitkan: | MDPI AG 2020-01-01 |
Deskripsi
The absorbance is of great importance in the tunable diode laser absorption spectroscopy (TDLAS) as it contains information of both gas properties and spectroscopic parameters. A novel, calibration-free wavelength modulation-direct absorption spectroscopy (WM-DAS) is proposed and experimentally verified in this two-part paper. This method combines the capability of absorbance measurement from DAS and the advantages of enhanced noise rejection and high sensitivity from WMS. In this <i>Part I</i>, we focus on the full theoretical basis and procedures of this method from the following three aspects: the high-accuracy characterizations of laser frequency and intensity, noise rejection ability by extracting the characteristic spectra through the fast Fourier transform (FFT) of the light intensity, and the simultaneous fitting strategy for both baseline and absorbance. The preliminary validation experiment of CO transition at 4300.6999 cm<sup>−1</sup> in a static gas cell shows the high accuracy of the proposed method.