Sensing atmospheric reactive species using light emitting diode by incoherent broadband cavity enhanced absorption spectroscopy

Abstract

We overview our recent progress in the developments and applications of light emitting diode-based incoherent broadband cavity enhanced absorption spectroscopy (LED-IBBCEAS) techniques for real-time optical sensing chemically reactive atmospheric species (HONO, NO₃, NO₂) in intensive campaigns and in atmospheric simulation chamber. New application of optical monitoring of NO₃ concentration-time profile for study of the NO₃-initiated oxidation process of isoprene in a smog chamber is reported.

Development of an incoherent broadband cavity-enhanced absorption spectrometer for measurements of ambient glyoxal and NO<sub>2</sub> in a polluted urban environment

“…IBBCEAS has been rapidly developed since Fiedler et al (2003) first described it in 2003. More recently, the technology has been successfully applied to measure a variety of trace gases (Min et al, 2016;Wang et al, 2017;Yi et al, 2016;Volkamer et al, 2015), weakly absorbed cross sections of different trace gases (Chen and Venables, 2011;Kahan et al, 2012) and aerosol extinction (Washenfelder et al, 2013). Using a xenon arc lamp as a light source, Washenfelder et al (2008) reported the first measurement of glyoxal using the IBBCEAS technique in the laboratory with a detection limit of 58 pptv (2σ ) within 1 min.…”

Cavity-enhanced photoacoustic sensor based on a whispering-gallery-mode diode laser

“…Cavity-enhanced absorption spectroscopy (CEAS) is based on the use of optical resonant cavities in order to enhance light interaction with a gas species inside the cavity (Gherman and Romanini, 2002;He et al, 2018;Yi et al, 2016). In CEAS setups, a proper locking between the laser wavelength and the cavity resonance mode must be carried out via two approaches: (i) the cavity length is controlled by a piezo transducer (PZT) for the resonance mode to follow laser wavelength; and (ii) the length of the cavity is fixed, and the laser wavelength is locked to the cavity resonance mode.…”

Dual-feedback mid-infrared cavity-enhanced absorption spectroscopy for H2CO detection using a radio-frequency electrically-modulated interband cascade laser

“…With an integration time of < 1.5 s, a detection limit of ~3 ppb was achieved by using direct absorption spectroscopy (DAS) and a multi-pass cell with a 54.6 m optical path length. Compared to a multi-pass gas cell, a F-P cavity is simple in structure, easy to adjust, low in attenuation and small in volume [13][14][15][16]. The Pound-Drever-Hall (PDH) technique was used to frequency stabilize the excitation laser to the cavity, which was successfully demonstrated on laser frequency stabilization of various wavelengths [17][18][19].…”