Measuring the 5νOH stretch absorption cross section of acetic acid and peracetic acid by cavity ringdown spectroscopy
Israel Begashaw1, Michael Collingswood2, Solomon Billilign3 1 Department of Physics, North Carolina A&T State University, Greensboro, NC 27401, USA
2Energy and Environmental Systems, North Carolina A&T State University, Greensboro, NC 27401, USA
3 Department of Physics, Energy and Environmental Systems, NOAA-ISET CSC North Carolina A&T State University, Greensboro, NC 27401, USA
In order to fully understand the chemistry and radiative balance of the atmosphere the need for instruments and techniques that have high sensitivity to measure weak absorptions is becoming increasingly significant. Studies have shown that weak absorption resulting from overtone transitions of atmospherically relevant molecules play significant roles in the overall chemistry of the atmosphere. Cavity ring-down spectroscopy (CRDS) is a highly sensitive laser based direct absorption technique that has been employed extensively in atmospheric science. We report on the success of setting up a cavity ring-down spectroscopic instrument at North Carolina A & T. We have calibrated and characterized our system using water vapor near 630nm and near 720nm. Our results for water vapor are in good agreement with that of the HITRAN 2008 spectroscopic database. We also report to the best of our knowledge for the first time the 5νOH stretch absolute absorption cross section for acetic acid and per acetic acid. Our preliminary results for acetic acid are similar to the 5νOH absorption cross section observed for HNO3 (Brown, Wilson et al. 2000). The minimum detectable absorption coefficient is αmin =3.42*10-9cm-1 Hz-1/2 at 2σ noise level near the peak of the absorption feature.
We would like to acknowledge support from NSF award #0803016 and NOAA-EPP award #NA06OAR4810187.
Corresponding Author: Israel Begashaw North Carolina A&T State University
Department of Physics
1601 E. Market St
Greensboro, NC 27411
336-334-7424 israelncat@gmail.com
PRESENTATION TYPE: Poster
TECHNICAL AREA: Climate and Global Change
AFFILIATION: STUDENT (Graduate)
CENTER AFFILIATION: ISET CSC
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