Novel Chemistry Using Molecular Beams
Description
Molecular beam methods provide rich possibilities for producing and studying novel species. These can include (1) clusters that would not be accessible in conventional gas phase chemistry and (2) generation and stabilization of reactive species. The methods that allow for (2) can be extended to (3) survey of evolving product chemistry following an initial fast impulse (photolysis, pyrolysis, electrical discharge) on some reactant. The projects undertaken touch on all three of these areas, but the centerpiece and most challenging project applies to the production, for the first time, of several novel organosilicon species. We first present an efficient molecular beam method of silylene production, a method meant to be used for the study of silylene chemistry. A particular goal was to produce a silanone. We present evidence that a silanone has been produced. Of even greater interest is the possible molecular beam production of small disilynes. This development would finally open the future opportunity to study these species in detail. Key to our approach here was the use of laser ablation of several different selected custom synthesized precursors. Based on past work, our expectation was that certain bonds in the precursors would selectively be broken, leading to the production of disilynes that then would be stabilized in cold gas expansions. For three different precursors, we present consistent evidence that the target disilynes were in fact produced. These conclusions were not clear in our initial analysis of the data; only a later and different form of analysis led to convincing evidence that the experiments were in fact successful. Because the main component of the intended project did not at first seem to have been successful, work in several other areas was carried out, related to themes (1) and (3). Related to (1) was methods development, demonstrating the ability to produce clusters of porphyrin and porphyrin-C60, for later extended study. For (3), study was carried out on the possible role of halogen adducts on alkylbenzenes in inhibiting PAH formation following corona discharge. Similarly for (3), method development was carried out to enable to study early product chemistry following the pyrolysis of triacylglycerols (triglycerides).