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 T17: Chemical Physics of Plasmonic Nanostructures: ImagingFocus
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Sponsoring Units: DCP Chair: Michelle Personick, Wesleyan University Room: Room 209 |
Thursday, March 9, 2023 11:30AM - 12:06PM |
T17.00001: Super-resolution imaging of molecular adsorption on single metal nanoparticles Invited Speaker: Peng Chen This talk will first give a brief introduction to the single-molecule fluorescence approaches to image catalytic reactions on single metal nanoparticles at super-optical resolution. It will present applications of such approaches to map the adsorption affinity of nonfluorescent reactants that can be converted into fluorescent products. It will then describe the development of a new approach, called COMPEITS, for super-resolution imaging of nonfluorescent processes on catalyst particles, as well as its application to study ligand adsorption on single metal nanoparticles, including the discovery of positive and negative adsorption cooperativity and adsorption crossover between different particle facets. |
Thursday, March 9, 2023 12:06PM - 12:18PM |
T17.00002: Super-Resolution Imaging of Corrosion by Single Molecule Fluorescence Microscopy Anuj Saini, Lydia Kisley Scientists and researchers have been studying corrosion since the founding of modern chemistry. A routine schematic in every general chemistry textbook shows individual electrons and metal ions undergoing reactions, diffusion, and dissolution at a pair of spatially-distinct electrodes — the cathode and anode — at a metal/solution interface. Yet, the correlation between the anode and cathode over both space and time has never been directly measured at the molecular scale. Physicists, electrochemists, and engineers give vastly different answers spanning orders of magnitude on the distance cathodic electrons can be detected away from anodic sites. |
Thursday, March 9, 2023 12:18PM - 12:30PM |
T17.00003: Characterizing the fluorescence of single chiral molecules in the near field of gold nanoparticles. Saaj Chattopadhyay, Julie Biteen There is considerable interest in increasing the sensitivity of chiral sensing because the intrinsic chirality of biomolecules is an indicator of structural and functional integrity. Single-molecule localization microscopy techniques detect the fluorescence of one molecule at a time and can therefore be leveraged to effectively conduct fluorescence-detected circular dichroism (FDCD) at the single-molecule level. The low differential absorption cross sections of individual molecules yield low signal-to-noise readouts, so we need to reshape the near-field electromagnetic field to enhance the difference between the absorbance of right-handed and left-handed light. Plasmonic Au nanoparticles act as antennas to focus incident plane waves and can be used to engineer optimal fields. However, due to the coupling of the molecular transition dipole and the electric dipole of the particle, the emission intensity does not only depend on absorption cross sections. Moreover, the emission pattern is strongly influenced by the engineered electromagnetic near field and the symmetry breaking results in emission mislocalization. Overall, for plasmon-enhanced FDCD to be a single-molecule chiral-sensing technique, the effect of Au nanoparticles on the fluorescence of a nearby chiral molecule must be characterized. In this talk, I will discuss the intensity and localization distributions of single-molecule fluorescence near plasmonic Au nanoparticle substrates. By varying the geometry of the substrate, the polarization of the incident beam, and the inherent chirality of the fluorescent dye while monitoring competing processes such as photo-bleaching and quenching, I will report on the shift between fluorescence intensity and localization of chiral and achiral molecules. The results, complemented with full-field electromagnetic simulations, will inform the feasibility of FDCD of single biomolecules. |
Thursday, March 9, 2023 12:30PM - 12:42PM |
T17.00004: Cavity-enhanced Dynamic Light Scattering of Single Proteins Lisa-Maria Needham, Julia Rasch, Beau Schweitzer, Cecilia H Vollbrecht, Carlos Saavedra, Daniel Sole-Barber, Alex J Fairhall, Randall H Goldsmith Measurements on single biomolecules provide a perspective of exceptional detail, enabling understanding of the underlying molecular mechanisms that govern biological processes. Most commonly, single-molecule measurements employ fluorescence which often requires the chemical attachment of fluorescent labels. As well as being perturbative to biomolecules and their interactions, labels limit the achievable resolution and sensitivity through complex photophysics. Recent developments in single-molecule label-free Rayleigh scattering based approaches have enabled the determination of the molecular weight of single biomolecules down to 30 kDa, however these techniques require proximity to surfaces and are temporally and shot noise limited. Microscale optical fiber based Fabry-Pérot cavities (FFPCs) provide a fully integrated route towards high sensitivity, label-free single-molecule measurements in the solution-phase. In this work we exploit both the small mode volume and high Q-factor of high reflectivity biconcave FFPCs to measure Purcell enhanced Rayleigh scattering from single proteins down to 1 kDa as they undergo Brownian motion in aqueous solution with 10 μs sampling rate. Here we improve the limit of detection 30-fold and the temporal resolution 100-fold compared to the current state-of-the-art. With this label-free technique we are able to determine the hydrodynamic radii of single proteins with unprecedented sensitivity. |
Thursday, March 9, 2023 12:42PM - 12:54PM |
T17.00005: Metallic bullseye nanostructured arrays as a highly active surface enhanced Raman scattering (SERS) substrate for detection of streptavidin/biotin assemblies Ziqi Li Ziqi (Amber) Li, † Carlos Fernandes, † and Harry E. Ruda†, *
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Thursday, March 9, 2023 12:54PM - 1:30PM |
T17.00006: Charge vs. energy transfer in plasmonic nanoparticles Invited Speaker: Christy Landes Because of the high absorption cross-section of plasmonic nanoparticles, they have exciting potential applications as photocatalysts. One barrier to this goal is that it is difficult to overcome the high probability for the energy absorbed to decay into heat. I will discuss recent results that rely on both charge transfer and energy transfer mechanisms to harness the plasmonic excitation to perform desirable chemistry. |
Thursday, March 9, 2023 1:30PM - 1:42PM |
T17.00007: Characterization of novel gold nanoparticles throughoptical spectroscopy and convolutional neural networks Niklas Gross Plasmonic nanoparticles exhibit large optical cross-sections that have attracted much interest for applications in photocatalysis, imaging, and nano-optics. However, the plasmonic behavior in these applications depends on particle properties such as relative proximity, crystallinity, size, and shape. The most common particle fabrication techniques, colloidal synthesis and electron beam lithography, allow to tailor these properties to an extent, yet typically result in particle-to-particle variations that broaden the plasmonic properties. Correlated single-particle approaches are required to resolve the governing mechanisms, but can be experimentally difficult and tedious. Here, we utilize polymer pen lithography to synthesize gold nanoparticles on glass and propose a strategy to characterize both their optical and structural properties through optical spectroscopy. We find that polymer pen lithography yields organized arrays of crystalline nanoparticles with controlled particle size, precise relative position, and high throughput. We take advantage of this synthesis technique by systematically measuring optical scattering spectra using an automated microscope. Through correlation with electron microscopy images, we build a convolutional neural network that predicts structural information from optical scattering. Our work suggests polymer pen lithography as a promising synthesis approach for plasmonic nanoparticles and offers an efficient way to study their properties. |
Thursday, March 9, 2023 1:42PM - 1:54PM |
T17.00008: Magneto-plasmonic nanoparticles for optical sensing of contaminants of emerging concern Carlos A Marquez Magneto-plasmonic nanoparticles are hybrid materials that combine features from ferromagnetic and noble metals. These types of nanoparticles exhibit outstanding optical properties of noble metals and the magnetic behavior of ferromagnetic materials. Due to their unique properties, in recent years the study of this type of nanoparticles is at the forefront of many nanotechnology applications such as catalysis, bio-separation, and chemical sensing. This work is focused on the development of an optical technique based on a total internal reflection configuration with the use of colloidal core-shell nanoparticles for the sensing of organic pollutants in freshwater. Specifically, gold-coated magnetite nanoparticles (Fe3O4@Au) will be studied due to the localized surface plasmon resonance (LSPR) of these nanoparticles that can be fine-tuned over a wide spectral domain. In addition, these particles exhibit magnetic properties that allow the facile manipulation of the nanoparticles in the presence of a permanent magnet. Simultaneously, the gold shell of these nanoparticles is optically active, which will enable analyte detection via fluctuations of the reflectance curve which occur when molecules bind to the gold surface. Computational as well as experimental work will be developed to synthesize and characterize the sensor capabilities. |
Thursday, March 9, 2023 1:54PM - 2:06PM |
T17.00009: Statistical Analysis of NIR to Visible Upconversion Luminescence from Single NaYF4:Yb3+,Tm3+ Nanoparticles on Nanocavity Arrays and Nanowire Substrates Kim Yip Chiok, Anahita Haghizadeh, Aravind Baride, Steve Smith, Robert B Anderson Tm-doped energy transfer upconversion (ETU) NaYF4: Yb3+:Tm3+ nanoparticles have potential applications in deep tissue imaging and energy conversion devices due to their visible (450nm) and infra-red (800nm) upconversion emission, but suffer from low quantum efficiency. We use single particle spectroscopic imaging and statistical analysis to assess the plasmonic enhancement of NIR-to-visible upconversion luminescence (UCL) from single β-NaYF4:Yb3+:Tm3+upconverting nanoparticles (UCNPs) supported on substrates consisting of random arrangements of Ag nanowire composites (NWCs) and Au nano-cavity arrays (NCAs). By examining the effects at the single particle level, and accumulating a statistical sampling of single particle emitters, both on and off the plasmonic substrates studied, we obtain a statistical description of UCL emission enhancement in the Tm-doped UCNPs and map out the statistical distribution of excitation and luminescence enhancement on the plasmonic substrates. The distributions obtained are compared to Finite Difference Time Domain (FDTD) calculations of the fields near the plasmonic substrate, assuming the variations are due to variations in UCNP coupling to the plasmonic substrate based on an exponential decay with distance. We use both wide field and confocal spectroscopic imaging of single UCNPs on and off the plasmonic substrates in combination with energy and time resolved spectroscopy and compare these results to a coupled rate equation analysis to elucidate the energy transfer upconversion enhancement mechanisms for these substrates. |
Thursday, March 9, 2023 2:06PM - 2:18PM |
T17.00010: Antenna-coupled infrared nano-spectroscopy of intra-molecular vibrational interaction Roland Wilcken, Jun Nishida, Johan F Triana, Aurelian John-Herpin, Hatice Altug, Felipe F Herrera, Markus B Raschke Ultrafast intramolecular vibrational energy transfer and redistribution (IVR) in the complex many-body environment of polyatomic molecules has a profound influence on molecular properties and chemical reactivity. In particular it limits coherence in applications like control of chemical reactivity or of single quantum levels. In order to investigate IVR, nonlinear multidimensional spectroscopy is the method of choice for large ensembles, but it is challenging to extend its sensitivity to probe small molecular ensembles and achieve nanoscale spatial resolution. Here we study the intramolecular coupling with IR nanospectroscopy in small ensembles in an IR-resonant nanoantenna coated with a molecular monolayer of a metal-carbonyl complex. By a combination of antenna resonance tuning and selective laser excitation of symmetric and asymmetric carbonyl modes we resolve the intramolecular vibrational coupling pathways from the effective vibrational lifetimes. A coupled quantum oscillator model quantifies the competition between intrinsic intra-molecular, extrinsic antenna-mediated vibrational energy transfer and Purcell enhancement of the vibrational lifetimes. As a nano-optical approach it allows to probe and control the low energy intramolecular vibrational energy landscape, with nanoscale spatial resolution and enhanced sensitivity with perspective into the single molecule regime. |
Thursday, March 9, 2023 2:18PM - 2:30PM |
T17.00011: Insights from single particle spectroscopy of plasmonic nanostructures Stephan Link A surface plasmon in a metal nanoparticle is the coherent oscillation of the conduction band electrons leading to both absorption and scattering as well as strong local electromagnetic fields. These fundamental properties have been exploited in many different ways, including surface enhanced spectroscopy and sensing, photothermal cancer therapy, and color display generation. The performance of plasmonic nanoparticles for a desired application not only depends on the particle size and shape, but is tunable through nanoparticle interactions on different length scales that support near- and far-field coupling. Chemical synthesis and assembly of nanostructures are able to tailor plasmonic properties that are, however, typically broadened by ensemble averaging. Single particle spectroscopy together with correlated imaging is capable of removing heterogeneity in size, shape, and assembly geometry and furthermore allows one to separate absorption and scattering contributions. In this talk I will discuss our recent work on understanding the radiative, non-radiative, chiral, electrochemical, and mechanical properties of individual and coupled plasmonic nanostructures including the generation and transfer of hot electrons to semiconductors as well as to liquids, for applications seeking to harvest light energy with hybrid plasmonic materials. |
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