Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session M50: JCP-DCP Editors ChoiceInvited
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Sponsoring Units: DCP Chair: Rigoberto Hernandez, Johns Hopkins University Room: Room 320 |
Wednesday, March 8, 2023 8:00AM - 8:36AM |
M50.00001: Single-molecule vibrational investigation in solution with fluorescence-encoded infrared spectroscopy Invited Speaker: Lukas Whaley-Mayda Single-molecule vibrational spectroscopy has enormous potential for investigating chemical phenomena with bond-level structural information. However, established methods rely on near-field signal enhancement mechanisms that require nanometer proximity to a surface or nanostructure, leaving solution-phase problems out of reach. We describe a new approach, fluorescence-encoded infrared (FEIR) spectroscopy, that couples IR-vibrational absorption to a fluorescent electronic transition to achieve high-sensitivity vibrational detection in solution with conventional far-field optics. Our approach uses a double resonance scheme that first excites vibrations by resonant IR absorption, followed by an electronically pre-resonant visible excitation ('encoding') that selectively brings the molecule to its fluorescent excited state. Femtosecond IR and visible pulses are used to make these transitions coincident within the picosecond vibrational lifetime, while splitting the IR pulse into a pulse-pair with an interferometer enables Fourier transform measurements of FEIR vibrational spectra. To demonstrate single-molecule sensitivity in solution, we introduce FEIR correlation spectroscopy—an IR-vibrational analogue of fluorescence correlation spectroscopy—and discuss its potential application as a vibrational probe of dynamic solution-phase chemical processes. |
Wednesday, March 8, 2023 8:36AM - 9:12AM |
M50.00002: Characterizing protein-surface and protein-nanoparticle conjugates: Activity, binding, and structure Invited Speaker: Lauren Webb Many sensors and catalysts composed of proteins immobilized on inorganic materials have been reported over the past few decades. Despite some examples of functional protein–surface and protein–nanoparticle conjugates, thorough characterization of the biological–abiological interface at the heart of these materials and devices is often overlooked. We will discuss current methods used to characterize these critical properties of devices that operate by integrating a protein into both flat surfaces and nanoparticle materials by focusing on acetylcholinesterase on both planar and nanoparticle gold. We highlight examples of how an informed understanding of the bio-bio interface leads directly to the advancement of protein-based materials and technology. |
Wednesday, March 8, 2023 9:12AM - 9:48AM |
M50.00003: Wavefunction Embedding for Molecular Polaritons Invited Speaker: Fabijan Pavosevic Polaritonic chemistry relies on the strong light-matter interaction phenomena for altering the chemical reaction rates inside optical cavities. To explain and to understand these processes, the development of reliable theoretical models is essential. While computationally efficient quantum electrodynamics self-consistent field (QED-SCF) methods, such as quantum electrodynamics density functional theory (QEDFT) needs accurate functionals, quantum electrodynamics coupled cluster (QED-CC) methods provide a systematic increase in accuracy but at much greater cost. To overcome this computational bottleneck, we introduce and develop the QED-CC-in-QED-SCF projection-based embedding method that inherits all the favorable properties from the two worlds, computational efficiency and accuracy. In this talk, we will discuss the implementation and porformance of the QED-CC-in-QED-SCF embedding method by studying methyl transfer reaction, proton transfer reaction, as well as protonation reaction in a complex environment. |
Wednesday, March 8, 2023 9:48AM - 10:24AM |
M50.00004: Non-thermal Vibrational Activation of Reactants in Plasmon Assisted Chemical Reactions Invited Speaker: Zee Hwan Kim Recent studies on plasmon assisted chemical reactions postulate that the hot-carriers of plasmon-excited nanostructures may induce a non-thermal vibrational activation of metal-bound reactants. However, a quantitatively validation at the level of molecular quantum states is currently missing. In this talk, I will present our recent spectroscopic studies on metal-bound reactants, which proves the non-thermal vibrational molecular excitations caused by plasmons: We find that such a plasmon- induced vibrational excitation causes hyper-thermal vibrational population distribution of a specific molecular vibrational mode, and bring significant population in overtone-excited states. Such excitation is found to be critically dependent on the metal-molecule chemical contact. The inelastic molecule-electron scattering model could fully explain what are observed. The result not only provides the physical basis for the plasmon-assisted chemical reactions, but also pave the way for controlling chemical reactions on metal surfaces. |
Wednesday, March 8, 2023 10:24AM - 11:00AM |
M50.00005: Order from disorder: guiding nanoscale crystallization of amorphous solids Invited Speaker: Paul G Evans Interfaces, stress, and precrystalline order have important roles in the nanoscale crystallization of amorphous solids. Crystallization processes at this scale impact fields including electronic materials, biomineralization, and atmospheric science. Similar fundamental nucleation and growth phenomena occur in a range of systems from complex oxide electronic materials to water and ice. In each case, crystallization is influenced at crystalline/amorphous interfaces by structural templating leading to the nucleation of crystals and to the selection of specific crystalline polymorphs. In addition to interface effects, the structural similarity between individual polymorphs and the amorphous form can lead to preferential nucleation of these polymorphs away from interfaces. A common feature among crystallizing amorphous materials is that the timescale that characterizes crystallization are longer than the Maxwell stress relaxation time. The nanoscale distribution of stress resulting from the density difference between amorphous and crystalline induces defect formation phenomena that are similar in multiple systems. Similarly, the timescale for relaxing chemical inhomogeneity can be sufficiently long that chemical profiles established within nanoscale amorphous layers are incorporated into the crystallized solids. Finally, there are indications that it is possible to design forms of amorphous materials to include structural chemical or structural features that influence subsequent crystallization phenomena. Further directions in influencing crystallization at the nanoscale can include the development of amorphous materials with these specific forms of chemical or structural order in the amorphous material, the design of nanoscale environments controlling the stress distribution, and extending similar concepts to a wider range of compounds. |
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