Measurements of weak absorptions by O 3 and O 3-H 2O clusters using cavity enhanced spectroscopy

Jessica Axson, Tara Kahan, Veronica Vaida, Rebecca Washenfelder, Cora Young, Steven S. Brown

Research output: Contribution to journalConference Articlepeer-review


Weak spectral absorptions play an important role in the radiative transfer of the Earth's atmosphere and are necessary for accurate satellite retrievals; additionally, weak electronic features in the near-UV are important for tropospheric radical production. This presentation focuses on ozone's near-UV spectrum, which is poorly characterized, with reported discrepancies up to one order of magnitude in the weakly absorbing spectral region between 350-450 nm. Theoretical calculations predict that O 3 will form O3-H 2O clusters that absorb in this region and may act as an atmospheric source of hydroxyl radicals. In this investigation we designed, constructed, and characterized a two channel incoherent broad-band cavity-enhanced absorption spectrometer (IBBCEAS) to provide accurate absolute absorption cross-sections for O 3 in the 350-450nm region. The instrument has an effective path length of several kilometers allowing for high sensitivity measurements of absorption cross sections in the near-UV, even for dilute trace gas levels. We have investigated the absolute absorption cross-section for ozone and the ozone-water complex in the region of 350 to 450 nm as a function of relative humidity. Results of this study will be discussed in light of their importance in atmospheric chemistry and atmospheric trace gas measurments.

Original languageEnglish (US)
JournalACS National Meeting Book of Abstracts
StatePublished - 2011
Externally publishedYes
Event242nd ACS National Meeting and Exposition - Denver, CO, United States
Duration: Aug 28 2011Sep 1 2011

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering


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