NSF Award
2404883
With support from the Chemical Structure and Dynamics (CSD) program in the Division of Chemistry, Professor Andrey Vilesov of the University of Southern California is investigating carbocations and molecular ionic clusters embedded in helium droplets at the ultracold temperature of 0.4 K via infrared spectroscopy. The structural information of cations and radicals is key to understanding their participation in chemical reactions, but exploration of these species is challenging because of their high reactivity and low concentration in a typical experiment. Weak interactions between helium atoms and ions make helium nanodroplets a unique matrix for the isolation and vibrational spectroscopy of ions. Professor Vilesov’s group will generate different carbocations and ionic clusters in helium droplets from neutral precursors by electron impact ionization. The resulting ions will be studied by mid-infrared laser spectroscopy and a time-of-flight mass spectrometer will enable simultaneous detection of the spectra of multiple ions. Their studies may provide insights into the structures of carbocation isomers and radical-cation clusters and could have broad implications to radiation chemistry and astrochemistry. This project will be performed by a diverse group of graduate, undergraduate, and high school students who will gain experience in modern physical chemistry experimentation and data analysis. <br/><br/>This project is focused on the elucidation of the structures of carbocations and molecular ionic clusters by isolating them in helium droplets at the ultralow temperature of 0.4 K. The droplets will be doped with molecules and ionized via electron impact producing embedded ions, which will be studied by laser spectroscopy in the mid-infrared range. These studies will contribute to a better understanding of the isomers of important carbocations, including C4H7+ and C7H11+, uncover the structures of radical-cation clusters such as (NH3)n+, and explore the products of ion-molecular reactions at ultralow temperature. The broader impact of this work involves gaining further understanding of radiation chemistry in the condensed phase and determining potential cationic intermediates necessary to produce aromatic and large organic molecules in the interstellar medium. This project will provide opportunities for training undergraduate and graduate students by developing and performing cutting-edge physical chemistry experiments and preparing ensuing publications. This project will also engage high school students who will be recruited from underserved areas of Los Angeles with the aim of encouraging them to pursue a career in a STEM field.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
