Double-grating spectrometer system for distinguishing N2 molecule rotation-vibration Raman spectrum

Abstract

The present invention discloses a double-grating spectrometer system for distinguishing a N2 molecule rotation-vibration Raman spectrum. The double-grating spectrometer system comprises a signal feeding unit, an optical dispersion unit and a signal detection unit. The signal feed unit employs cluster fibers to feed signal light in the optical dispersion unit; the optical dispersion unit includes two groups of single-grating dispersion systems with cascade quasi-Littrow structure layout; and the signal detection unit is configured to distinguish and record spectrum signals after dispersion in the pass band range. Under the ultraviolet laser radiation with wavelength of 354.8nm, the Stokes rotation-vibration Raman spectrum center generated by N2 molecules has a wavelength of 386.8nm, and each spectral line of the O branch spectrum and the S branch spectrum symmetrically distributed at two sides are arranged at regular intervals on the frequency spectrum. The double-grating spectrometer system for distinguishing a N2 molecule rotation-vibration Raman spectrum is able to extract signals of each branch spectral line of the O branch spectrum and the S of the N2 molecule rotation-vibration Raman spectrum, realize the distinguishing and detection of the N2 molecule rotation-vibration Raman spectrum and generates great inhibition of optical signals closed to 354.8nm.

Description

technical field [0001] The invention relates to a method capable of distinguishing and detecting N 2 A dual-grating spectrometer system for vibrational Raman spectrum signals generated by molecules. Background technique [0002] Under the irradiation of extremely narrow linewidth (<0.1pm) laser, atmospheric molecules (mainly including N 2 and O 2 molecules, etc.) would interact with the laser and produce secondary radiation. The spectrum produced by the secondary radiation includes both the elastic Rayleigh spectrum and the inelastic Raman spectrum. The Rayleigh spectrum has no frequency shift relative to the emitted laser wavelength, which is the same as the emitted laser wavelength; the Raman spectrum has a frequency shift relative to the emitted laser wavelength, which is different from the emitted laser wavelength. Raman spectrum includes pure rotational Raman spectrum and vibrational Raman spectrum. The pure rotational Raman spectrum has a certain frequency shif...

AI Technical Summary

Problems solved by technology

Since the pure rotational Raman spectra produced by different molecules overlap each other in the spectrum, it is very difficult to completely resolve and extract the pure rotational Raman spectrum produced by a single molecule. For example, the spectral resolution accuracy of the spectrometer must reach the order of 1pm, which is impossible for traditional spectrometers qualified for this job

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