TY - JOUR
T1 - Acousto-optic differential optical absorption spectroscopy for atmospheric measurement of nitrogen dioxide in Hong Kong
AU - Cheng, Andrew Y.S.
AU - CHAN, Mau Hing
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2004/12
Y1 - 2004/12
N2 - Measurement of the atmospheric concentration of nitrogen dioxide (NO 2) pollutant was demonstrated by differential optical absorption spectroscopy (DOAS) using a visible acousto-optic tunable filter. In a traditional spectral scanning DOAS system for atmospheric concentration monitoring, a highly stable light source is required. When the light intensity fluctuates during scanning, the concentration retrieval will be inaccurate. In order to reduce the error due to intensity fluctuations, a modified DOAS system has been developed by introducing a broadband light intensity monitoring channel. Using the measured intensity of the broadband channel as the intensity of the light source, the spectrum can be de-biased and the residual intensity variation will primarily result from atmospheric extinction. In addition, by employing the lock-in detection technique, the background light interference is also removed in the modified DOAS system. The atmospheric NO2 concentration measurement was performed at the campus of City University of Hong Kong, and the results were compared with the concentration reported from a nearby monitoring station in Sham Shui Po, operated by the Hong Kong Environmental Protection Department.
AB - Measurement of the atmospheric concentration of nitrogen dioxide (NO 2) pollutant was demonstrated by differential optical absorption spectroscopy (DOAS) using a visible acousto-optic tunable filter. In a traditional spectral scanning DOAS system for atmospheric concentration monitoring, a highly stable light source is required. When the light intensity fluctuates during scanning, the concentration retrieval will be inaccurate. In order to reduce the error due to intensity fluctuations, a modified DOAS system has been developed by introducing a broadband light intensity monitoring channel. Using the measured intensity of the broadband channel as the intensity of the light source, the spectrum can be de-biased and the residual intensity variation will primarily result from atmospheric extinction. In addition, by employing the lock-in detection technique, the background light interference is also removed in the modified DOAS system. The atmospheric NO2 concentration measurement was performed at the campus of City University of Hong Kong, and the results were compared with the concentration reported from a nearby monitoring station in Sham Shui Po, operated by the Hong Kong Environmental Protection Department.
KW - Acousto-optic tunable
KW - Atmospheric pollutant monitoring
KW - Differential absorption spectroscopy
KW - Visible spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=10644221321&partnerID=8YFLogxK
U2 - 10.1366/0003702042641317
DO - 10.1366/0003702042641317
M3 - Journal article
C2 - 15606960
AN - SCOPUS:10644221321
SN - 0003-7028
VL - 58
SP - 1462
EP - 1468
JO - Applied Spectroscopy
JF - Applied Spectroscopy
IS - 12
ER -