title: [Research on the influence of LED temperature shifts on differential optical absorption spectroscopy for measuring NO2].
abstract: Influences of LEDs (without etalon structure and center wavelengths are respectively 370 nm (near-UV), 452 nm (blue) and 660 nm(red)) temperature shifts on differential optical absorption spectroscopy(DOAS) for measuring NO2 were studied. NO2 absorption spectra were formed using LED emitting spectra at 10 degrees C. The measured LED spectra at other temperatures were used as reference spectra of DOAS. Thus, NO2 differential optical densities under different LED temperature shifts were acquired and then NO2 differential cross-sections were fitted to the acquired differential optical densities. From fitting results, the linear relations of 0.995, 0.945 and 0.989 correlation between delta of fitting residual and near-UV, blue and red LEDs temperature shifts were found and their slopes are respectively 1.12 x 10(-3), 5.25 x 10(-5) and 7.45 x 10(-4) degrees C(-1). The fitting results show that the influence of temperature shifts of blue LED on DOAS retrieval is negligible and the temperature shifts of near-UV and red LED are impressible to DOAS measurement resulting in degradation of detection sensitivity. The retrieval results of blue LED with and without etalon with similar temperature properties were compared and showed that etalon of LED will greatly increase the influence of temperature shifts of LED on DOAS retrieval.
authors: Anhui Institute of Optics and Fine Mechanics, Key Laboratory of Environmental Optics & Technology, Chinese Academy of Sciences, Hefei 230031, China. lyling@aiofm.ac.cn
authors: Liu-Yi
authors: LY
authors: Ling
authors: Pin-Hua
authors: PH
authors: Xie
authors: Min
authors: M
authors: Qin
authors: Ni-Na
authors: NN
authors: Zheng
authors: Cong-Lei
authors: CL
authors: Ye
authors: Ang
authors: A
authors: Li
authors: Ren-Zhi
authors: RZ
authors: Hu