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Fundamental Spectroscopic Studies of Transition Metal Nitrides and Carbides

Year: 2023

Presenter Name: Yexalen Barrera-Casas

The scientific exploration of the chemical bonds in transition metal nitrides (MN) is integral to a multitude of scientific fields. Some pertinent examples include the study of the Fe-Nitrogen bonds within the hemoglobin protein, electrochemical energy applications, and a deeper understanding of the complexities MN species demonstrate in organometallic chemistry. Although multiple studies have analyzed the general bonding mechanisms and schemes between transition metal and nitrogen atoms, there is a current lack of accurate and precise data on the fundamental bond dissociation energies (BDEs) for MN species. This shortage of thermochemical BDEs prevents the elucidation of quantitative and qualitative trends on the chemical bondings, electronic structures, and overall fundamental characteristics of MN species. Here, I present the predissociation thresholds of early and late 3d, 4d, and 5d MN species with the use of jet-cooled molecular beams through Resonant Two-Photon Ionization (R2PI) spectroscopy. The measured predissociation thresholds can be accurately assigned to the BDEs of the MN species studied within this work: D0(ScN) = 3.905 eV, D0(TiN) = 5.015 eV, D0(YN) = 4.125 eV, D0(MoN) = 5.220 eV, D0(RuN) = 4.905 eV, D0(RhN) = 3.659 eV, D0(HfN) = 5.374 eV, D0(OsN) = 5.732 eV, and D0(IrN) = 5.115 eV. The R2PI spectra resolve a dense manifold of molecular vibronic states at energies below the ground separated atom limit. When the MN species of interest is energetically excited to exactly the ground separated atom limit, the transition metal-nitrogen bond is broken and at energies above the predissociation threshold, a baseline of zero molecular signal is resolved. The electronic structures of the MN species can be put into context of these spectroscopically resolved thermochemical BDEs, allowing for the fundamental underpinnings of the chemical bond between transition metals and nitrogen to be illuminated.
University / Institution: University of Utah
Type: Poster
Format: In Person
Presentation #D53
SESSION D (3:30-5:00PM)
Area of Research: Science & Technology
Faculty Mentor: Michael Moore