1. State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China 2. School of Mechanical and Precision Instrument Engineering, Xi’an University of Technology, Xi’an 710048, China 3. National Institute of Metrology, Beijing 100013, China
Abstract：A method for online quantitative analysis system of alkane gaseous mixture with near infrared spectroscopy is described in the present paper. A single plane diffraction grating is used as the principal device in the monochromatic spectrum system. The key parameters of the monochromator were deduced and calculated in detail. A quantitative analysis system was designed and constructed according to the parameters. The narrow-band beam testing experiments and spectral scanning experiments of seven kinds of single-component alkane gases were accomplished on the above hardware system platform. The narrow-beam experiments show that a 10 nm narrow-band beam spectra was successfully obtained by the monochromatic system when the entrance slit width is 2 mm. And a step-scanning resolution of the outgoing beam’s center wavelength with 0.1 nm can be realized within the spectra of 1.2～1.8 μm. The spectral scanning experiments indicate that there was some stronger characteristic absorption spectrum existing between the spectra of 1.6～1.8 μm, which is consistent with the HITRAN spectral database. And there is serious cross-aliasing phenomenon existing among the absorption spectra. These experiments demonstrate that this method has a successful application in mixed gas monitoring and on-line analysis with the characteristics of simple structure and low cost. And it also provides further technical reserves and opens a path way to spectral analysis in the follow-up studies.
