Incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) is increasingly finding applications in atmosphere chemical, environmental monitoring, and medical diagnostics, etc. The paper describes the application of IBBCEAS for measurements of atmospheric NO_2 using a blue LED centered at the wavelength of about 445 nm. The reflectivity of the cavity mirror is calibrated based on the difference between the Rayleigh scattering cross sections of N2 and He. The detection limit for NO_2 detection is related to the integration time and averaging number. This issue is addressed by performing experimental measurements under different integration time and averaging number to determine the optimum condition. The measurement results are useful for the design of a spectroscopic sensor for monitoring atmosphere NO_2.
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