Dibble Group - Research Projects

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Electron Beams for Degradation of Airborne Pollutants
Ignition of Biodiesel Fuel
Alkoxy Radical Spectroscopy and Kinetics
Atmospheric Chemistry of Mercury
Cavity Ringdown Spectroscopy (CRDS)
Alkoxy and peroxy radicals from isoprene

1)   Electron Beams for Degradation of Airborne Pollutants. Irradiated air samples are analyzed by GC or GC-MS to determine the efficiency of destruction of the pollutant and to identify and quantify the degradation products. Kinetic modeling is used to understand factors controlling degradation efficiency. Spectroscopy ( see below) will be used to measure radical concentrations and characterize the plasma.

2)   Ignition of Biodiesel Fuel Peroxy radicals formed in radical chain chemistry can undergo chain branching: each peroxy radical can form two new reactive hydroxyl radicals. This process causes ignition of diesel fuel (or knocking in spark-ignition engines). Researchers have achieved a molecular-level understanding of the kinetics of these reactions in peroxy radicals derived from alkanes, but not for radicals likely to be formed from biodiesel fuel (fatty acid methyl esters). We will investigate the kinetics and mechanisms of these reactions using quantum chemistry and statistical rate theory. An example of the chemistry of interest is shown below.

image showing ROO to QOOH reaction   arrhenius

3)   Alkoxy Radical Spectroscopy and Kinetics. Past work centered on alkoxy radicals from saturated alkanes, but is being extended to alkoxy radicals with various functional groups. We have a particular interest in b-hydroxy alkoxy radicals (e.g., HOCH2CH2O), which are both atmospherically important and possess intramolecular hydrogen bonds donated from the hydroxy group to the radical center. A new project involves determining the extent of isotope effects in the competing reactions:

CH2DO + O2 → CH2=O + DO2
CH2DO + O2 → CHD=O + HO2
The experimental study, carried out in collaboration with NCAR's Laboratory Kinetics Group, will provide data needed to better model the atmospheric cycle of molecular hydrogen. The data will provide a stringent test of our theoretical results for this tricky reaction.

4)   Atmospheric Chemistry of Mercury We have some ideas about atmospheric chemistry of mercury which we have explored with quantum calculations and experiments are being planned on that basis. This project benefits from coordination with another chemistry faculty member, Dr. Huiting Mao.

5)   Cavity Ringdown Spectroscopy (CRDS) CRDS in the near-infrared is used to measure temperature and OH radical concentration in plasmas, both the electron beam discussed above and a variety of other non-thermal plasmas. This project is being carried out in collaboration with Dr. Chuji Wang at Mississippi State University.

6)    Alkoxy and peroxy radicals from isoprene and related molecules.  About 500 Mtons of isoprene (2-methyl-1,3-butadiene) is emitted to the atmosphere each year, where it affects local and global ozone as well as aerosol production. Quantum chemistry is used to determine the atmospheric reaction pathways of alkoxy and peroxy radicals from this critical compound. An important aspect of these radicals is their intramolecular hydrogen bonding, which can lead to some double H-atom jumps, as shown below.

Department of Chemistry
1 Forestry Drive
Syracuse, NY 13210
(315) 470-6596 (Dr. Dibble)
(315) 470-4780 (Lab)
(315) 470-6856 (fax)
Dr. Dibble's Official Web Page

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