Peroxy radical detection for airborne atmospheric measurements using absorption spectroscopy of NO2
Peroxy radical detection for airborne atmospheric measurements using absorption spectroscopy of NO2
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DOI：
10.5194/amt-7-1245-2014
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发表时间：
2014-01-01
影响因子：
3.8
通讯作者：
Burrows, J. P.
中科院分区：
文献类型：
--
作者：
Horstjann, M.;Hernandez, M. D. Andres;Burrows, J. P.
Development of an airborne instrument for the determination of peroxy radicals (PeRCEAS - peroxy radical chemical enhancement and absorption spectroscopy) is reported. Ambient peroxy radicals (HO2 and RO2, R being an organic chain) are converted to NO2 in a reactor using a chain reaction involving NO and CO. Provided that the amplification factor, called effective chain length (eCL), is known, the concentration of NO2 can be used as a proxy for the peroxy radical concentration in the sampled air. The eCL depends on radical surface losses and must thus be determined experimentally for each individual setup. NO2 is detected by continuous-wave cavity ring-down spectroscopy (cw-CRDS) using an extended cavity diode laser (ECDL) at 408.9 nm. Optical feedback from a V-shaped resonator maximizes transmission and allows for a simple detector setup. CRDS directly yields absorption coefficients, thus providing NO2 concentrations without additional calibration. The optimum 1 sigma detection limit is 0.3 ppbv at an averaging time of 40 s and an inlet pressure of 300 hPa. Effective chain lengths were determined for HO2 and CH3O2 at different inlet pressures. The 1 sigma detection limit at an inlet pressure of 300 hPa for HO2 is 3 pptv for an averaging time of 120 s.
