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Raman spectrum excitation structure and gas analysis method

A Raman spectroscopy and gas analysis technology, applied in the field of Raman spectroscopy, can solve the problems of low damage threshold of internal optical components, short laser-molecular interaction distance, short laser-molecular interaction distance, etc., achieving low cost, simple structure, excitation Efficient effect

Pending Publication Date: 2020-01-10
INST OF NUCLEAR PHYSICS & CHEM CHINA ACADEMY OF
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The traditional confocal Raman spectrometer has a relatively high detection limit for gas molecules due to the short laser-molecular interaction distance (micron level) and the low damage threshold of internal optical components (generally less than 500 mW laser power), which cannot meet the requirements of the current industry. Testing requirements
In view of the above problems, there is an urgent need to study a gas Raman signal enhancement technology for industrial gas detection to solve the problem of short laser molecular action distance and high detection limit.

Method used

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  • Raman spectrum excitation structure and gas analysis method

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Effect test

Embodiment 1

[0037] This embodiment specifically illustrates the present invention with 12 reflection Raman spectrum excitation structures, as figure 1 As shown, the test gas sample is selected as hydrogen isotope gas, and a 1.5 W 660 nm wavelength laser is used. The laser has completed 12 reflections in the multi-reflection cavity composed of a concave mirror 1 and three planar reflections 2. The gas molecules are Inspired 12 times. Specifically, the excitation laser beam enters the excitation structure from the left, passes through the concave mirror 1 and the upper and lower plane mirrors 2, and finally reaches the middle plane mirror 2. The beam passes through the excitation structure six times. Wherein, the function of the middle plane mirror 2 is to let the laser beam leave the excitation structure along the original path, and finally the light beam passes through the excitation structure 12 times in total. The gas Raman signal is focused on the optical fiber collection surface thro...

Embodiment 2

[0039] The embodiment of this embodiment is basically the same as that of Embodiment 1, the main difference is that the test gas sample is selected as air. In the three-second test time, the detection limit of nitrogen and oxygen gas is about 22 Pa, and the detection limit of water molecule is 10.9 Pa.

Embodiment 3

[0041] The implementation of this embodiment is basically the same as that of Embodiment 1, the main difference is that the sealed hydrogen isotope gas has been tested at multiple points for more than 100 hours, and the analysis results show that for hydrogen isotope gas molecules, the relative accuracy of this set of Raman spectrometer testing Both are less than 0.5%, with good stability and repeatability.

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Abstract

The invention discloses a raman spectrum excitation structure and a gas analysis method. The excitation structure employs a concave-surface reflecting mirror and multiple planar reflecting mirrors, anexcitation laser acts with a gas sample for many times, an action distance between the laser and a gas molecule is expanded, so that the raman signal of the gas molecule is improved, and the excitation structure is simple and is low in cost and good in stability. According to the raman spectrum excitation structure-based gas analysis method, the problems of low excitation efficiency, poor systemstability and the like brought by the application of a conventional excitation structure are solved, the excitation structure is high in excitation efficiency and good in repeatability and is simple to install in a glove box, the advantages of relatively long action distance between the laser and the gas molecule and relatively low detection limit are achieved, and quantitative analysis of a special mixed gas of hydrogen isotope, methane and sulfur dioxide also can be achieved.

Description

technical field [0001] The invention belongs to the technical field of Raman spectroscopy, and in particular relates to an excitation structure for analyzing hydrogen isotope mixed gas. Background technique [0002] Hydrogen isotopes protium (H), deuterium (D), and tritium (T) combine with each other to form homonuclear hydrogen H2, D2, T2 and heteronuclear hydrogen HD, HT, DT. The analysis of hydrogen isotopes by Raman spectroscopy has the advantages of simple operation, non-destructive and online measurement. The composition ratio of hydrogen isotopes can be obtained by accurately measuring the intensity of its rotational (S branch) or vibrational (Q branch) peaks. Since the rotational peak intensity is related to the balance of positive and parahydrogen, and is greatly affected by the background, the hydrogen isotope Raman vibration peak is More for component analysis. However, due to the low density of gas molecules and the small Raman scattering cross section, it is q...

Claims

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Application Information

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IPC IPC(8): G01N21/65G01N21/01
CPCG01N21/658G01N21/01G01N2021/0112
Inventor 温成伟黄鑫李海容王伟伟
Owner INST OF NUCLEAR PHYSICS & CHEM CHINA ACADEMY OF