[MOS] December 10, 2013, Terry Miller, Ohio State University

[Zina M Queen]

Seminar on

Modern Optics and Spectroscopy

 

Exploring the high-resolution spectroscopy of molecules that can affect the quality

of your life

 

Terry Miller,

Ohio State University

 Tuesday, December 10, 2013

12:00pm-1:00pm

Few things affect your quality of life more than the air you breathe and the temperature of your immediate environment. Since more than 80% of the energy used in the industrialized world today is still derived from fossil fuels, these two quantities are not unrelated. Annually more than 100 Tg of organic molecules are injected into the troposphere and are mostly degraded via oxidative processes involving free radical intermediates. Many of those intermediates are the same as the ones involved in the combustion of fossil fuels. Two of the key oxidizing intermediates are hydroxyl, OH (day), and nitrate, NO3 (night), radicals and early oxidation intermediates of organic compounds include the alkoxy (RO) and peroxy (RO2) families of radicals. The spectroscopy of OH is well known, but there is still a lot to be learned about the spectroscopy of RO, RO2, and NO3 radicals both for diagnostic purposes and in terms of characterizing their molecular properties and benchmarking quantum chemistry calculations. Both peroxy radicals and NO3 have weak Ã-X̃ electronic transitions in the near infrared (NIR). We have utilized moderate resolution cavity ringdown spectroscopy (CRDS) to study ambient temperature radicals and high resolution (HR-CRDS) to study these jet-cooled radicals. Comparable laser induced fluorescence (LIF) measurements have been made for the alkoxy species.  This talk will focus on the similarities (and differences) of the electronic structure of the RO, RO2, and NO3 radicals and the spectra observed at room temperature and under free-jet conditions. The capability of the spectra to provide unambiguous diagnostics for monitoring the concentrations and reactions of these radicals will be discussed. Both vibrational and rotational resolution of the electronic spectra is possible. Data obtained from the spectral observations provide information about both the geometric and electronic structure of these radicals as well as their dynamics.

Grier Room, MIT Bldg 34-401

Refreshments served after the lecture



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