The combination of broadband light sources with the path length enhancement achievable with an听optical cavity allows for spectrally resolved optical extinction. 听Light emitting diodes (LEDs) are high power light sources with a bandwidth comparable to that of high reflectivity mirrors. 听Dispersion听of the light transmitted through an optical cavity with a grating spectrometer and CCD detector provides high sensitivity measurements听of atmospheric trace gases and aerosols
The Airborne Cavity Enhanced Spectrometer is a two-channel instrument with LEDs at 455 and 365 nm that measures glyoxal (CHOCHO), methyl glyoxal (CH3COCHO), nitrogen dioxide (NO2) and nitrous acid (HONO). 听It has been deployed at ground sites in China and the U.S., and on the NOAA P-3 aircraft in the southeast and western U.S. (SENEX 2013 and SONGNEX 2015). 听It will fly on the NASA DC-8 in the 2019 FIREX-AQ campaign to characterize the atmospheric chemistry of biomass burning emissions.
References
Washenfelder, R.A., A.R. Attwood, J.M. Flores, K.J. Zarzana, Y. Rudich, and S.S. Brown, Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde. Atmos. Meas. Tech., 2016. 9(1): p. 41-52.听
Min, K.E., R.A. Washenfelder, W.P. Dub茅, A.O. Langford, P.M. Edwards, K.J. Zarzana, J. Stutz, K. Lu, F. Rohrer, Y. Zhang, and S.S. Brown, A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor. Atmos. Meas. Tech., 2016. 9(2): p. 423-440.听听
Washenfelder, R.A., J.M. Flores, C.A. Brock, S.S. Brown, and Y. Rudich, Broadband measurements of aerosol extinction in the ultraviolet spectral region. Atmos. Meas. Tech., 2013. 6: p. 861-877.听听
Washenfelder, R.A., A.O. Langford, H. Fuchs, and S.S. Brown, Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer. Atmos. Chem. Phys., 2008. 8: p. 7779-7793.听