Date: Tuesday, January 17th, 2023
Time: 1:00 - 2:30 pm EST

Plenary Lecture

Dr. Michael Ruggiero, University of Vermont

Title of Talk: Characterizing and controlling material function with terahertz vibrational spectroscopy

Abstract: Over the past two decades, terahertz time-domain spectroscopy has become a valuable technique for the characterization of solid samples, primarily due to its sensitivity to bulk molecular packing arrangements. However, in recent years the role that specific terahertz vibrations play in a number of important physical phenomena has become increasingly apparent, with numerous studies highlighting how terahertz motions are directly responsible for the proper functioning of materials, ranging from enzymatic catalysis to solid-state phase transformations. In this work, terahertz spectroscopy is used to study a number of solid-state material phenomena, including the role of electron-(THz)phonon coupling for charge carrier dynamics in organic semiconductors, gas loading in porous materials (metal-organic frameworks and hydroquinone clathrates), and polymorphic/order-disorder transitions in molecular crystals. In all cases, specific terahertz motions exist that are responsible for these specific phenomena, enabling a direct 1-to-1 mapping of critical processes to a signal low-frequency vibrational resonance. Finally, recent work in using terahertz radiation to coherently control solid-state phase transitions will be discussed, and future directions into this exciting area of vibrational spectroscopy with be explored.

Time: 1:00 pm

Short Talks

Heather Calcaterra, Northwestern University

Title of Talk: Shape Memory in Self-Adapting Colloidal Crystals

Abstract: Mechanically responsive crystals, which exhibit reversible, rapid, and complex dynamics, are essential to the development flexible electronics, artificial muscles, and various dynamic components in soft robotics. Due to the limited flexibility of the atomic bonds making up the crystals, to date, only a limited number of deformation modes can be obtained in mechanically responsive crystals. To address this limitation, we report the reversible mechanical responsiveness of colloidal crystals engineered with DNA bonds to deformations typically considered irrecoverable in conventional molecular and atomic crystals. These advances were obtained through the synthesis of large (>50 um) single crystals, which enable previously unrealizable characterization techniques including in-situ optical microscopy and single-crystal x-ray diffraction, as well as subsequent study of their state-switchable optical properties. This work sheds light on both the unprecedented nature of the macroscale deformation and recovery as well as the flexible and resilient internal structure of DNA-engineered crystals.

Time: 1:40 pm

Armando Navarro-Huerta, Universidad Nacional Autónoma de México (UNAM)

Title of Talk: Intermolecular Charge-Transfer Interactions as Plausible Pathway for the Modification of Rotational Dynamics in Cocrystals

Abstract: Intermolecular Charge-Transfer interactions have become a plausible, accessible and low-cost methodology for the development of new, organic crystalline materials with good performances in optoelectronic devices. In this talk, it is presented the effect of the addition of symmetric, small acceptor fragments to carbazole/phenanthrene-based molecules towards the formation of cocrystals with novel, different photophysical properties from their constituents. Techniques such as VT Single-crystal X-Ray Diffraction, VT Solid-State NMR and Solid-state photoluminescence measurements were employed to elucidate both the structure and dynamics of the employed solids. The results shed light in the effect of the cocrystallization of the donor and acceptor moieties on the dynamic properties of the cocrystals herein presented.

Time: 2:05 pm EST