caa a22 4500 445372737 CHVBK 20180317142952.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s00340-010-4266-5 doi (NATIONALLICENCE)springer-10.1007/s00340-010-4266-5 Simultaneous measurements of atmospheric HONO and NO2 viaabsorption spectroscopy using tunable mid-infrared continuous-wave quantum cascade lasers [Elektronische Daten] [B. Lee, E. Wood, M. Zahniser, J. McManus, D. Nelson, S. Herndon, G. Santoni, S. Wofsy, J. Munger] Nitrous acid (HONO) is important as a significant source of hydroxyl radical (OH) in the troposphere and as a potent indoor air pollutant. It is thought to be generated in both environments via heterogeneous reactions involving nitrogen dioxide (NO2). In order to enable fast-response HONO detection suitable for eddy-covariance flux measurements and to provide a direct method that avoids interferences associated with derivatization, we have developed a 2-channel tunable infrared laser differential absorption spectrometer (TILDAS) capable of simultaneous high-frequency measurements of HONO and NO2. Beams from two mid-infrared continuous-wave mode quantum cascade lasers (cw-QCLs) traverse separate 210 m paths through a multi-pass astigmatic sampling cell at reduced pressure for the direct detection of HONO (1660cm−1) and NO2 (1604cm−1). The resulting one-second detection limits (S/N=3) are 300 and 30 ppt (pmol/mol) for HONO and NO2, respectively. Our HONO quantification is based on revised line-strengths and peak positions for cis-HONO in the 6-micron spectral region that were derived from laboratory measurements. An essential component of ambient HONO measurements is the inlet system and we demonstrate that heated surfaces and reduced pressure minimize sampling artifacts. Springer-Verlag, 2010 Lee B. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut Wood E. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut Zahniser M. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut McManus J. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut Nelson D. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut Herndon S. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut Santoni G. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut Wofsy S. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut Munger J. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut Applied Physics B Springer-Verlag 102/2(2011-02-01), 417-423 0946-2171 102:2<417 2011 102 340 https://doi.org/10.1007/s00340-010-4266-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00340-010-4266-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lee B. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut NATIONALLICENCE 700 1- Wood E. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut NATIONALLICENCE 700 1- Zahniser M. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut NATIONALLICENCE 700 1- McManus J. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut NATIONALLICENCE 700 1- Nelson D. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut NATIONALLICENCE 700 1- Herndon S. Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc., Billerica, MA, USA aut NATIONALLICENCE 700 1- Santoni G. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut NATIONALLICENCE 700 1- Wofsy S. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut NATIONALLICENCE 700 1- Munger J. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA aut NATIONALLICENCE 773 0- Applied Physics B Springer-Verlag 102/2(2011-02-01), 417-423 0946-2171 102:2<417 2011 102 340 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer