Photoionization Mass Spectrometry and Photoelectron-Photoion Coincidence (PEPICO) Spectroscopy Studies of Select Biofuel Molecules

Publication Year:
2013
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Downloads 205
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Repository URL:
https://repository.usfca.edu/thes/206
Author(s):
Czekner, Joseph G
Tags:
Photoionization; mass spectrometry; photoelectron-photoion coincidence; biofuels; Physical Chemistry
thesis / dissertation description
This thesis is the culmination of numerous experiments, performed on two different continents, investigating the spectroscopic and thermodynamic properties of several biofuels and fuel additives. It will start with an introduction about the motivation behind these experiments. The second chapter will outline the experimental details of the apparatus at the Advanced Light Source (ALS) in Berkeley, CA, followed by the Swiss Light Source (SLS) in Villigen, Switzerland. Third, the theoretical concepts and data analysis methods will be discussed in detail.Chapter 4 will be the start of the newly obtained data. It presents some photoionization mass spectrometry studies on γ-valerolactone (GVL). The photoionization cross section of GVL and some suspected combustion products are measured. In addition, several dissociative ions are determined. Theoretical calculations are used to support all alignments. This data is vital to product identification and branching fraction calculations in time- and energy-resolved photoionization experiments. The fifth chapter will investigate the chlorine-initiated reactions of methyl butyrate (MB) and ethyl butyrate (EB) in the presence of oxygen. Ethyl crotonate is found to be a major product in the EB reaction. Formaldehyde and acetaldehyde are both formed in the EB and MB reactions. Both products are suspected to be produced by the RO2-HO2 radical-radical reaction and ­ab initio calculations are performed to analyze the reaction mechanisms. Finally, chapter six will discuss the photoelectron-photoion coincidence (PEPICO) spectroscopy of two biofuel additives (GVL and mesitylene). This technique is used to measure various thermodynamic quantities, such as heats of formation, entropies of activation, and bond strengths. In addition, dissociation rates will also be obtained with the use of two statistical models, Rice-Ramsperger-Kassel-Marcus (RRKM) theory and the Simplified Statistical Adiabatic Channel Model (SSACM).