TY - JOUR
T1 - Amplitude-Modulated Cavity-Enhanced Absorption Spectroscopy with Phase-Sensitive Detection
T2 - A New Approach Applied to the Fast and Sensitive Detection of NO2
AU - Zhou, Jiacheng
AU - Zhao, Weixiong
AU - Zhang, Yang
AU - Fang, Bo
AU - Cheng, Feihu
AU - Xu, Xuezhe
AU - Ni, Shichuan
AU - Zhang, Weijun
AU - Ye, Chunxiang
AU - Chen, Weidong
AU - Venables, Dean S.
N1 - Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/2/22
Y1 - 2022/2/22
N2 - Accurate and sensitive measurements of NO2play an extremely important role in atmospheric studies. Increasingly, studies require NO2measurements with parts per trillion by volume (pptv-level) detection limits. Other desirable instrument attributes include ease of use, long-term stability, and low maintenance. In this work, we report the development of an amplitude-modulated multimode-diode-laser-based cavity-enhanced absorption spectroscopy (AM-CEAS) system operating at 406 nm that uses phase-sensitive detection for extremely sensitive NO2detection. The laser was TTL-modulated at 35 kHz. The mirror reflectivity was determined to be 99.985% based on the ring-down time measurement. The cavity base length was 47.5 cm, giving an effective absorption pathlength of∼3.26 km. AM-CEAS achieved a 1σ detection precision of 35 pptv in a 1 s data acquisition time (4.98 × 10-10cm-1), over 4 times lower than that attained using a ring-down approach and the same optical system. The AM-CEAS precision improved to 8 pptv over a data acquisition time of 30 s (1.14 × 10-10cm-1). The AM-CEAS method with the multimode diode laser integrates the advantages of high light injection efficiency like on-axis alignment cavity ring-down spectroscopy, low cavity-mode noise like off-axis alignment CEAS, and narrow-bandwidth high-sensitivity weak signal detection of modulation spectroscopy, providing a powerful, straightforward, and general method for ultrasensitive absorption and extinction measurements.
AB - Accurate and sensitive measurements of NO2play an extremely important role in atmospheric studies. Increasingly, studies require NO2measurements with parts per trillion by volume (pptv-level) detection limits. Other desirable instrument attributes include ease of use, long-term stability, and low maintenance. In this work, we report the development of an amplitude-modulated multimode-diode-laser-based cavity-enhanced absorption spectroscopy (AM-CEAS) system operating at 406 nm that uses phase-sensitive detection for extremely sensitive NO2detection. The laser was TTL-modulated at 35 kHz. The mirror reflectivity was determined to be 99.985% based on the ring-down time measurement. The cavity base length was 47.5 cm, giving an effective absorption pathlength of∼3.26 km. AM-CEAS achieved a 1σ detection precision of 35 pptv in a 1 s data acquisition time (4.98 × 10-10cm-1), over 4 times lower than that attained using a ring-down approach and the same optical system. The AM-CEAS precision improved to 8 pptv over a data acquisition time of 30 s (1.14 × 10-10cm-1). The AM-CEAS method with the multimode diode laser integrates the advantages of high light injection efficiency like on-axis alignment cavity ring-down spectroscopy, low cavity-mode noise like off-axis alignment CEAS, and narrow-bandwidth high-sensitivity weak signal detection of modulation spectroscopy, providing a powerful, straightforward, and general method for ultrasensitive absorption and extinction measurements.
UR - https://www.scopus.com/pages/publications/85124887398
U2 - 10.1021/acs.analchem.1c05484
DO - 10.1021/acs.analchem.1c05484
M3 - Article
AN - SCOPUS:85124887398
SN - 0003-2700
VL - 94
SP - 3368
EP - 3375
JO - Analytical Chemistry
JF - Analytical Chemistry
IS - 7
ER -