Excimer laser photofragmentation/fragment detection for analysis of the oxygenated hydrocarbon ethyl-3-ethyoxypropionate: implications for atmospheric monitoring.

In the present study, the use of ArF excimer laser photofragmentation/fragment detection (PF/FD) is considered for the characterization of gaseous ethyl-3-ethyoxypropionate (EEP), a representative solvent within the class of oxygenated volatile organic compounds (VOCs). PF/FD measurements of EEP resulted in identification of the resulting photofragments as C2 and CH, allowing photofragmentation pathways to be proposed for the parent molecule for the first time. In addition, PF/PD measurements of EEP recorded in the presence of sodium-based aerosol particles resulted in a reduced signal from the EEP, indicating adsorption onto the particulates, thereby demonstrating proof-of-concept that PF/FD can be used to study heterogeneous chemical reactions relevant to atmospheric chemistry. Finally, both time-integrated and time-resolved measurements of the EEP photofragmentation signal in varying concentrations of oxygen revealed that oxygen effectively acts as a dynamic quencher of the EEP signal. In consideration of oxygen quenching, care must be taken in calibrating/analyzing data in selected applications of PF/FD for VOC characterization (such as combustion emission monitoring) in order to account for the potential variability of oxygen concentration.