Knowledge Bank

\maketitle Free radicals are key components in the oxidation ofhydrocarbons, both in combustion and in our atmosphere. More specifically, the vinoxy radical, CH$2$CHO, is a prototypical alkenoxy radical, which is known to play an important role in the reaction of O($3$P) and OH with olefins and olefinic radicals. While the $B~$ - $X~$ transition of vinoxy has been studied in considerable detail over the last twenty years, the $A~$ - $X~$ transition remains relatively unexplored because of its much weaker absorption cross-section. Due to its low oscillator strengh, cavity ringdown spectroscopy (CRDS) has been applied to study the $A~$ - $X~$ near-IR electronic transition of vinoxy radical. In addition, \textit{ab initio} calculations were conducted in order to predict the $A~$ - $X~$ origin frequency, as well as to aid in assigning other vibrational structure in the spectrum.