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Title:High Resolution Anion Photoelectron Spectra Of Cryogenically Cooled Silicon Carbides
Author(s):Babin, Mark C
Contributor(s):Neumark, Daniel; DeVine, Jessalyn A.; Weichman, Marissa L.; DeWitt, Martin
Abstract:High-resolution anion photoelectron spectra of cryogenically cooled Si$_3$C$^{-}$, Si$_2$C$^{-}_2$, and SiC$^{-}_3$ obtained using slow photoelectron velocity-map imaging (cryo-SEVI) are presented, providing insight into the geometries, energetics, and vibronic structure of the anionic and the neutral clusters. These spectra yield accurate vibrational frequencies for the neutral clusters. They also yield refined adiabatic detachment energies (ADEs) for the ground states of Si$_3$C$^{-}$ and Si$_2$C$^{-}_2$ of 1.5374(6) eV and 1.9019(4) eV, respectively, while the ADE of a low-lying isomer of SiC$^{-}_3$ is found to be 1.9050(7) eV. The cryo-SEVI spectra show that the ground state of Si$_2$C$^{-}_2$ is a distorted trapezoid, and represent the first confirmation of the distorted trapezoid structure of Si$_2$C$^{-}_2$, the only low-lying isomer of this cluster with a permanent dipole moment. Additional transitions are observed from two low-lying anion isomers: a linear structure and a rhombus. The spectrum of SiC$^{-}_3$, in combination with electronic structure calculations, suggests that the true ground state of SiC$_3$ is a ring structure with a transannular C–C bond, addressing a longstanding controversy surrounding this cluster. All three spectra exhibit Franck-Condon forbidden transitions; these are attributed to Herzberg-Teller coupling in Si$_3$C and SiC$_3$ and autodetachment from an excited electronic state of Si$_2$C$^{-}_2$.
Issue Date:2021-06-23
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper / Presentation
Date Available in IDEALS:2021-09-24

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