a n 2 Measurement System of Molecular Vibrational Raman Spectroscopy

Abstract

The invention discloses a measuring system of N2 molecule vibration-rotation Raman spectrum. The system comprises an emission unit and an optics reception and signal detection unit. The emission unit irradiates the atmospheric molecules by using the ultraviolet laser with extremely narrow linewidth of 354.8 nm outputted by a seed-injected solid-state laser. The optics reception and signal detection unit collects the signal of the vibration-rotation Raman spectrum produced by the N2 molecule, uses a double grating dispersion system to disperse the light in a range of 384.9-388.6 nm in space with a linear dispersion of 8.3 mm / nm, uses a linear array detector having 32 channels to distinguish and record discrete spectral line signals of O branch (rotation quantum number J=16-2) and S branch (rotation quantum number J=0-14) of N2 molecule vibration-rotation Raman spectrum, and produces inhibition better than 13 order of magnitude for the light near 354.8 nm. The system realizes the distinction and record of N2 molecule Stokes vibration-rotation Raman spectrum, and can obtain temperature information.

Description

technical field [0001] The invention relates to a method capable of distinguishing and recording by N 2 A measurement system for vibrational Raman spectra 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 shift relative to the em...

AI Technical Summary

Problems solved by technology

If the Raman spectrum completely generated by a single molecule can be obtained, then, based on the envelope of the Raman spectrum of the entire molecule, the temperature can be directly obtained without external temperature source calibration! But on the spectrum, N 2 and O 2 Molecular pure rotational Raman spectra overlap each other, and it is necessary to completely resolve N 2 or O 2 The pure rotational Raman spectrum of molecules is very difficult. For example, the spectral resolution accuracy of the spectrometer system is required to reach the order of 1pm. Traditional spectrometers are not up to the task.

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