Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session Q02: Nanoscale PhenomenaRecordings Available
|
Hide Abstracts |
Chair: Kaitlin Hellier, University of California, Santa Cruz Room: McCormick Place W-175C |
Wednesday, March 16, 2022 3:00PM - 3:12PM |
Q02.00001: Kinetics of Laser-Induced Nanowelding of Silver Nanoparticles in Solution Yong Wang, Ariel Rogers, Isabelle Niyonshuti, Alice Cai, Feng Wang, Mourad Benamara, Jingyi Chen It is of importance and interest to understand the nanowelding process of metallic nanoparticles illuminated by lasers due to its potential for providing convenient and controlled ways for shape-conversion of nanoparticles and fabrication of nanodevices. However, the real-time kinetics of the nanowelding process were rarely reported in the literature. In this work, we applied fluorescence microscopy to directly image the nanowelding process of silver nanoparticles (AgNPs) under the illumination of continuous wave laser at 405 nm, and observed the formation of branched structures or assemblies due to nanowelding. By the sizes of the laser-induced assemblies, we observed that the kinetics of nanowelding followed an exponential law. We developed an analytical model based on simple polymerization predict and understand the measured kinetics, and experimentally verified the model by examining the dependence of the nanowelding kinetics on the laser power and the concentration of AgNPs. Furthermore, we observed that the formed higher-order structures were separated into different photoluminescent domains, showing asynchronous, uncorrelated blinking behaviors. |
Wednesday, March 16, 2022 3:12PM - 3:24PM |
Q02.00002: Novel analysis of dynamical complexities in finite-size systems Darya Aleinikava, Julius Jellinek Finite-size systems present additional complexities in their dynamical behavior as compared to extended systems. The analysis and characterization of these added complexities demand new tools and descriptors. Here we present the notion of Dynamical Degrees of Freedom (DDF) and illustrate its utility in the understanding of the complex stage-wise meltinglike transition in bimetallic Ni/Al clusters. The similarities and differences between the energy-driven changes in the DDF in bimetallic clusters and their one-component counterparts will be pointed out. The discussion will also include more traditional descriptors, such as caloric curve, RMS bond-length fluctuation, and heat capacity. |
Wednesday, March 16, 2022 3:24PM - 3:36PM |
Q02.00003: Fluorophores “turned-on” by corrosion reactions can be used to monitor corrosion in non-aqueous environments at the single-molecule level. Zachary C Gatland, Lydia Kisley, Anuj Saini
|
Wednesday, March 16, 2022 3:36PM - 3:48PM |
Q02.00004: Imaging excited-state dynamics of individual nanoparticles using single-molecule absorption scanning tunneling microscopy Alison Wallum, Zetai Liu, Joseph W Lyding, Martin Gruebele Characterizing the unique optical phenomena of nanomaterials has been a central theme in understanding how we can leverage these materials for applications in fields including photocatalysis and renewable energy. However, techniques often used to probe optical properties of these materials rely on detection of bulk material properties. Given the significant population of defects or structural variations that are innate to most nanomaterial syntheses, understanding precisely how heterogeneity affects the properties of these materials is critical, and requires single-particle techniques capable of probing both the structural and excited state electronic properties on the nm scale. To measure excited-state dynamics of single nanoparticles with spatial sub-nm resolution and temporal sub-ps resolution, our group employs an excited state imaging technique known as single-molecule absorption scanning tunneling microscopy (SMA-STM). We will discuss applications of this technique and preliminary STM data for characterizing the excited state structure and energy transfer dynamics of carbon dots to understand their fluorescence mechanism and quantum dots designed for triplet energy transfer. |
Wednesday, March 16, 2022 3:48PM - 4:00PM |
Q02.00005: Quantum Enhancement of the Spin-Thermopower in Single-Molecule Junctions Nathan Bennett The thermoelectric effect allows heat to be directly converted into electricity in a device with no moving parts. In systems with broken time-reversal symmetry, a spin-voltage may be generated in response to a temperature gradient via the analagous spin-thermopower effect. |
Wednesday, March 16, 2022 4:00PM - 4:12PM |
Q02.00006: Can finite armchair nanotubes host organic color centers? Benjamin R Eller, Jacob Fortner, Jacek Klos, YuHuang Wang, Charles W Clark Fluorescent sp3 defects made with organic molecules covalently bound to single-walled carbon nanotubes (nanotubes), known as organic color centers (OCCs), are promising room-temperature sources of single-photons. While creating an OCC in a metallic nanotube is an interesting prospect due to the ballistic transport properties of the charge carriers, to date all OCCs have been made in semiconducting nanotubes. Here we present time-dependent density functional theory calculations on (6,6) armchair nanotube segments that show that the introduction of sp3 defects to the surfaces of the nanotubes results in singlet excited states with non-zero oscillator strength, lower in energy than the previously dominant low-lying transition (within the set of the first 10 singlet excited states). This suggests the possibility of creating OCCs in metallic nanotubes, since OCCs fluoresce by providing a new radiative pathway for excitons to recombine via photoemission. |
Wednesday, March 16, 2022 4:12PM - 4:24PM |
Q02.00007: Interaction confinement in nanoscale ion transport Nikita Kavokine, Paul Robin, Lydéric Bocquet Fluid transport at the nanoscale is fundamental to various processes, from neurotransmission to ultrafiltration. Yet, it is only recently that well-controlled channels with cross-sections of a few molecular diameters became accessible experimentally [1]. When aqueous electrolytes are confined within such channels, the Coulomb interactions between the dissolved ions are reinforced due to dielectric contrast at the channel walls: we call this effect interaction confinement. Interaction confinement leads to ionic correlations, which we have previously shown to result in several non-linear transport phenomena, including ionic Coulomb blockade and memristor effects [2,3]. In this talk, I will show that interaction confinement can be tuned by the electronic properties of the channel wall material. I will introduce a new formalism, based on surface response functions, that links the effective Coulomb interactions within a channel to the wall's band structure, described to any desired level of precision [4]. These results provide a quantitative approach to controlling nanoscale ion transport through the choice of the channel wall material. |
Wednesday, March 16, 2022 4:24PM - 4:36PM |
Q02.00008: Cavity-mediated charge transfer in a donor-acceptor photovoltaic: experiments and modeling insights Andrew E Sifain, Kyu H Park, Francesca Fassioli, Courtney A DelPo, Gregory D Scholes, Weijun Wu Light-induced charge and energy transfer is the basis of many natural and engineered light-harvesting systems such as photosynthetic complexes and photovoltaics. While much work has focused on synthetic design strategies to optimize and control this process, a new field of research has emerged in which strong coupling between quantized light and matter enables drastic changes in a material's potential energy landscape and eigenstate structure. By embedding a material in an optical microcavity, its polarization strongly interacts with a confined electromagnetic field mode to form hybridized light-matter states known as polaritons. How polaritons can be leveraged to access unseen and useful charge and energy transfer pathways has stimulated a lot of interest. In this talk, I will discuss recent spectroscopic experiments in our group on a cavity-embedded donor-acceptor photovoltaic (P3HT/PCBM) demonstrating that charge transfer can proceed by means of polariton states despite the photon's relatively short lifetime (~100 fs). I will also present a model Hamiltonian of the combined electron-hole-photon system together with open quantum dynamics simulations that provide insights into the underlying relationships between system properties and the production of free charge carriers including the strength of light-matter coupling and energetic disorder, the latter of which notably localizes the exciton and inhibits efficient formation of charge-transfer states. By studying this model, we capture energetic and coupling regimes in which polaritons can potentially outperform the energy conversion efficiency in bare organic photovoltaics. |
Wednesday, March 16, 2022 4:36PM - 4:48PM |
Q02.00009: Coordination Effect of Metal Centers in Electrochemical CO2 Reduction: A First-Principles Mechanistic Study Haiying He, Chunhui Liu Recent development of single-atom or few-atom catalysts have demonstrated superior catalytic performance owing to their under-coordinated structure and unique electronic properties in contrast to their bulk counterparts. The catalytic metal centers are highly sensitive to neighboring physical and chemical environment. In this study, we have adopted transition metal dimers supported on modified graphene sheets as our model catalysts and conducted first-principles calculations for electrochemical CO2 reduction. The coordination of these metal centers is varied in a systematic way, which in turn has a profound effect on the catalytic behavior. Their catalytic reactivity and product selectivity is discussed in light of the electronic structure, the oxidation state and the bonding feature of these metal centers. The insights provide further guidance on engineering the coordination of metal centers for purpose-driven applications. |
Wednesday, March 16, 2022 4:48PM - 5:00PM |
Q02.00010: STM Study of Dithia[7]Helicenes and the Role of an Organic Solvent at Ambient Conditions Tamara de Ara García, Carlos Sabater, Bianca C. Baciu, Carla Borja-Espinosa, Patricia Ferrer-Alcaraz, Alberto Guijarro, Carlos Untiedt Using a Scanning Tunneling Microscope (STM), we study a solution of the chiral molecule dithia[7]helicene ([7]DTH) in benzene. Two different [7]DTH were synthesized with sulfur atoms integrated in different locations displaying two different topologies. After the deposition and evaporation on Au(111), we studied the molecular arrangement over the surface, showing differences due to the interaction of the sulfur atom as a link group with the gold atoms. In our study we could image the different binding configurations of the molecules and characterize their main characteristics including their chirality. |
Wednesday, March 16, 2022 5:00PM - 5:12PM |
Q02.00011: Engineering the transport orbital in a molecular nanoscale junction Luca Ornago, Abdalghani Daaoub, David Vogel, Sara Sangtarash, Marcel Mayor, Herre van der Zant, Hatef Sadeghi Metal-molecule-metal junctions are of fundamental interest for integration in electronic devices as molecules are the smallest objects whose properties can be tailored by chemical design1. Tuning charge transport through molecules requires engineering of the molecular orbital whose energy lie closest to the Fermi level of the contacts. This can be achieved through the introduction of proper side-groups on the molecular backbone2. In this work we study the charge transport properties of a series of tolanes using the Mechanically Controllable Break Junction (MCBJ) technique, paired with Density Functional Theory (DFT) calculations. The molecules have been substituted either with electron-withdrawing nitro-groups, or electron-donating dimethylamino-groups. Effects of the anchoring were also investigated by using two different types of binding groups: thioacetate- and methylsulfanyl-, which form covalent and dative bonds to gold respectively. The investigated side groups are able to shift the energy levels and shrink the HOMO-LUMO gap as expected, as shown both by DFT calculations, Cyclic Voltammetry and UV/Vis spectroscopy. However, MCBJ measurements do not reflect these changes. This effect can be explained with DFT calculations by considering that the Fermi energy of the contacts can take on a wide range of values. |
Wednesday, March 16, 2022 5:12PM - 5:24PM |
Q02.00012: Long-term memory and synapse-like plasticity in carbon-based nanofluidic channels Paul Robin, Théo Emmerich, Antoine Niguès, Alessandro Siria, Lydéric Bocquet, Abdul Ismail, Ashok Keerthi, Andre K Geim, Radha Boya Fine-tuned ion transport across nanoscale pores is key to many biological processes such as the process of information in the brain. Such advanced functionalities are still far outside the reach of bio-inspired nanofluidic systems. However, a milestone has been reached very recently with the design of nanoscale carbon-based slits, whose conductance exhibits long-term memory emerging from the slow dynamics of the system's surface [1,2,3]. In this talk, I will show that this plastic memory can be harnessed to mimic that of biological synapses. In addition, we designed an experiment recreating a form of Hebbian learning, where the system’s conductance is updated according to the relative activation times of two neurons. This allows us to implement an elementary, bio-inspired learning algorithm with nanofluidic building blocks, paving the way for the development of advanced iontronics. |
Wednesday, March 16, 2022 5:24PM - 5:36PM |
Q02.00013: Quantum interfacial phenomena in nanoscale water flows: unconventional friction and hydrodynamic Coulomb drag Baptiste Coquinot, Nikita Kavokine, Lydéric Bocquet Quantum effects are scarce in soft matter systems, where the dynamics are typically described using some version of Newton’s equations. Yet, as the study of water flows is pushed to smaller and smaller scales, there appear phenomena that defy understanding in terms of classical theories of fluid transport. In particular, there is growing evidence for the coupling between fluid flows at the nanoscale and the electronic properties of the confining walls, resulting in both unconventional friction [1] and generation of electric currents inside the wall material [2]. In this talk, I will present some of our latest work on such quantum interfacial dynamics. Starting from the pioneering theoretical work on quantum friction [3], I will discuss the remarkable features of this phenomenon when water flows are confined down to the angström scale. I will then show how the framework of friction is generalized to account for current generation, through a mechanism that we call hydrodynamic Coulomb drag. Finally, I will discuss the favorable comparison between our theoretical predictions and recent experimental data. |
Wednesday, March 16, 2022 5:36PM - 5:48PM |
Q02.00014: Memory effects in bidimensional carbon nanochannels Theo Emmerich, Abdul Ismail, Paul Robin, Ashok Keerthi, Andre K Geim, Radha Boya, Alessandro Siria, Lydéric Bocquet Memristors are electronic devices enabling both information storage and in-place processing. They are at the core of many recent, bio-inspired attempts of overcoming the challenges faced by modern computers, from energy consumption to computation time. However, most of these devices rely on solid-state technologies to operate, in contrast with the brain’s purely electrolytic machinery. Here we report a novel memristor effect in recently developed carbon bidimensional ionic channels1. We show that these nanofluidic memristors have hour-long memory and demonstrate that the effect can be tuned by changing the type of ion. Our results can be rationalized in terms of an accumulation of ions inside the channel due to its asymmetric entrance. Our nanofluidic memristor can serve as a foundation for biomimetic iontronic applications. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700