14
Cavity
Attenuation Phase Shift Spectroscopic Detection of Nitrogen Dioxide--Aerodyne
Research, Inc., 45 Manning Road, Billerica, MA
01821-3976; 978-663-9500, www.aerodyne.com
Dr.
Andrew Freedman, Principal Investigator,
Dr.
Charles E. Kolb, Business Official,
DOE
Grant No. DE-FG02-03ER83598
Amount:
$750,000
Nitrogen
dioxide emissions are regulated by a national ambient air quality standard under
the 1970 Clean Air Act. The
prevalent means of detection, a chemiluminescence-based monitor (the so-called
NOx box), often provides inaccurate readings for nitrogen dioxide in the
presence of other nitrogen-containing trace atmospheric species.
This project will build an uncomplicated, inexpensive, and accurate
spectroscopic sensor for the detection of nitrogen dioxide at the
sub-part-per-billion level using Cavity Attenuation Phase Shift spectroscopy
(CAPS), a technique related to cavity ringdown laser absorption spectroscopy.
It relies on the measurement of small shifts in the phase of modulated
light that is transmitted through a resonant optical cavity induced by the
absorption of the target species. In
Phase I, a proof-of-principle demonstration of a CAPS-based nitrogen dioxide
sensor was performed. Results
indicated that the CAPS-based sensor had sensitivity less than 1 part per
billion of nitrogen dioxide. A
calibrated CAPS sensor accurately monitored ambient NO2
concentrations at the 0-40 ppb level over the course of a two day observation
period, without the need for human intervention.
In Phase II, an improved field-hardened prototype instrument, intended to
provide sensitivity less than 1 ppb of NO2 with a 30 second sampling time, will
be designed, built, and tested.
Commercial
Applications and Other Benefits as
described by awardee: Compact,
inexpensive and accurate nitrogen dioxide point sensors, suitable as tools for
the measurement of urban pollution, will be needed as concerns about atmospheric
pollution increase. Markets for this
instrument should include the atmospheric research community, and entities that
provide routine monitoring of exhaust from gas turbines, chemical plants, and
refineries.