Three Pulses Walk Into a Molecule: Vibrational Interactions and Manifolds Revealed via 2DIR Spectroscopy
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Authors
Mallon, Christopher
Issue Date
2022
Type
Thesis
Language
Keywords
2DIR , Infrared Probe , Tyrosine , Vibrational Coupling
Alternative Title
Abstract
Two-Dimensional Infrared Spectroscopy (2DIR) is a powerful technique that can be used to investigate the dynamics and interactions of vibrational modes in molecular systems. Its ability to distinguish between the different broadening mechanisms that lead to the infrared absorption linewidth, as well as its ability to resolve vibrational coupling and energy transfer on ultrafast timescales, make it one of the most powerful ways to study molecular vibrations.Herein, 2DIR will be used in two studies. The first will focus on the development of infrared probes to detect peptide and protein structure. The ability of 2DIR to resolve molecular structures relies on the distance and orientation dependence of the coupling between molecular vibrations. These are typically studied using small vibrational probes, such as the stretching mode of the nitrile group, that can be detected without perturbing the molecular structure. So far, the available IR probes that can be used to study the structure of biomolecules are limited. In this work, we investigate the use of tyrosine, deuterated tyrosine, and carbon-13 labeled alanine as native infrared probes that can be incorporated in biomolecules to detect peptide and protein structures. The second study will investigate the vibrations that occur in organic ligands, which can be incorporated in Single-Molecule Magnets (SMMs). These systems display magnetic hysteresis on a molecular level, but their magnetization states decohere from their interactions with the vibrational degrees of freedom in the organic ligand, thus limiting the temperatures at which they can effectively operate. To understand the role of vibrations in these decoherence pathways, we will use 2DIR to study one organic ligand, terpyridine-NO2, in the lowest energy region available in our current setup to reveal a complex web of coupled vibrations.