Novel method for simultaneously measuring absorption coefficient of aerosol at multiple wavelengths through single photoacoustic cell

Abstract

The invention discloses a method for simultaneously measuring an absorption coefficient of an aerosol at multiple wavelengths through a single photoacoustic cell. The method comprises the steps that amplitude modulation is conducted on multiple laser devices with different wavelengths through square signals which are generated by a function generator at the frequency intervals of df, lasers with different wavelengths are emitted into the photoacoustic cell after being subjected to beam combination through a fiber optic combiner, the lasers emitted into the photoacoustic cell interact with the aerosol in the photoacoustic cell, and a photoacoustic signal P<m>(f0+ / -f) reflecting an absorption signal of aerosol particles is generated; the absorption coefficient of the aerosol at the multiple wavelengths is obtained through calculation according to a deduced absorption coefficient formula at different modulation frequencies. The method solves the problems of spatial and temporal heterogeneity of samples and particle losses caused by measurement conducted through multiple photoacoustic cells, the measuring process is simpler, and the system structure is more compact. By means of the method, the aerosol absorption Angstrom coefficient can be obtained, components of the aerosol can be recognized, and therefore a valuable decision making basis is provided for traceability and governance of haze.

Description

technical field [0001] The method belongs to the field of optics. The invention relates to a new method for simultaneously measuring the optical absorption coefficient of aerosol at multiple wavelengths with a single photoacoustic cell. The method uses photoacoustic spectroscopy combined with a Fourier transform data processing method to realize the wavelength dependence of the aerosol optical absorption coefficient. Real-time online measurement of properties. Background technique [0002] With the rapid growth of my country's economy, industrial production, urban traffic and other production and living activities have become more and more serious pollution to the atmospheric environment, and large-scale, long-term smog weather has become more frequent, which is harmful to the healthy development of the national economy and the people. Therefore, it is particularly urgent to trace the source of smog and carry out targeted governance on this basis. Atmospheric aerosol is one...

AI Technical Summary

Problems solved by technology

[0011] The present invention is mainly used to solve the complex problem of system structure and operation caused by multiple photoacoustic cells when measuring aerosol multi-wavelength absorption, and provides a method for online measurement of wavelength-dependent characteristics of atmospheric aerosols using a single photoacoustic cell

This method can avoid the spatiotemporal inhomogeneity of sample distribution caused by gas shunting during the measurement process and the loss of aerosol particles during the process, and can identify its components according to the measured wavelength-dependent characteristics of the aerosol

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