Files
Abstract
Helium nanodroplet isolation is used to trap hydrocarbon radicals produced by thepyrolysis of appropriate precursors. The infrared spectra, predominantly in the CHstretching region, of a variety of hydrocarbon radicals is discussed. High-level theoretical computations using the VPT2+K method are used to compare the spectra of each radical and make assignments when feasible. Cyclobutylmethyl nitrite is used as a pyrolytic precursor to the cyclobutyl radical, the spectrum of which is presented herein. Upon higher temperature pyrolysis, decomposition products of the cyclobutyl radical are observed, specifically, products that occur as a result of a ring-opening mechanism.These results are compared to the existing potential energy surface (PES) for C4H7species. The infrared spectra of fulvenallene and the fulvenallenyl radical are alsodiscussed. Spectra in the acetylenic CH stretching region for the fulvenallenyl radicalprovide valuable information about the extent of the unpaired electrons delocalizationthroughout the conjugated propargyl and cyclopentadienyl subunits. These results areaided by spin density calculations based on Mullikan populations. Anharmonictheoretical computations are used to make spectral assignments and provide insight into the identity of other species formed during the initial pyrolysis process. Finally, apreviously published physical chemistry experiment is transformed into an undergraduate SCALE-UP activity. As an extension of fundamental physical chemistry research, this activity serves as an example of how undergraduate curriculum can benefit from merging research with classroom content. Two versions of the activity will be presented along with an analysis of student definitions for entropy before and after completing the activity.