Engineering Phonons in Hybrid Nanostructures by Design and Understanding Their Roles in A Few Physical Processes

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Non-Technical AbstractPhonons are the collective vibrations of the atoms in a solid and can be thought of as particles moving though the solid. They are responsible for many properties such as the thermal conductivity and thermal expansion of materials. They even play a role in how materials will perform in new applications such as for quantum computing. Understanding, and even harnessing, how these particles interact with each other is essential for designing and optimizing new materials. This project focuses on understanding how phonons interact in a few select physical processes. This research is accomplished by employing multidisciplinary experimental tools, ranging from materials design and synthesis of colloidal quantum structures to ultrafast optical spectroscopy, and it thus provides a fertile ground for students' training, K-12 outreach and curriculum development. Technical AbstractThis project supports an experimental activity with a goal to understand phononic interactions at the nanoscale and to address a few phonon-mediated fundamental processes by adopting a multi-pronged experimental approach. It particularly combines ultrafast optical spectroscopy with pre-designed colloidal hybrid nanostructures that can possess well-defined nanoscale interface topology for phonon engineering. This research directly involves graduate students training in tools and techniques needed to address a few fundamental issues: effect of interfacial symmetry (centrosymmetric vs. non-centrosymmetric interfaces) on nanoscale phonon characteristics; all optical control of interfacially coupled phonons and their interplay in time domain; understanding interactions between optically excited phonons and other quantum dynamics. Accomplishment of this project should advance our nanoscale materials engineering capability and new design guidelines for desirable phonon properties, as well as our understanding of phonon-dependent physical processes. This work is additionally important because hybrid nanostructures with well-defined interface topology for phonon engineering can be utilized as building blocks for functional phononic devices. In addition to graduate and undergraduate students' laboratory training, this project also allows for integrated education platform with cutting-edge research activities in classroom and various outreach activities with particular focus on underrepresented minority students' education.