Photonics in Chemical Physics
September 26-28, 2021
Organized by Chemical Physics Reviews
Times listed as EDT
September 26 – Day 1
Welcome: 12:00pm – 12:15pm
Speaker: Phil Castellano
AIP Academy Session
12:15pm – 2:15pm
Session Chair: Katherine VanDenburgh
A session designed to help you navigate key topics related to publishing and peer review. See our author resource page here: https://publishing.aip.org/resources/researchers/publishing-academy/
12:15pm – 1:15pm
How to publish your science: An editor’s guide on writing a manuscript that engages readers
Speaker: Amanda Sulicz, AIP Publishing, USA
Abstract: Scientific papers may have a rigidly defined structure and can be largely considered “artless prose,” but there’s still room to tell a compelling story that clearly communicates the science. This presentation discusses how to structure research papers to attract the readers’ attention and ensure that writers get the message across to their audience. The presentation will offer ideas and examples on how to compose an abstract that communicates effectively and create a title that is informative, accurate, clear, and concise.
1:15pm – 2:15pm
Hypes, hoaxes and fraud: the thin line between selling and overselling your science
Speaker: Ferdinand Grozema, Delft University of Technology, Netherlands
Abstract: Writing is an important part of modern science as it matters a lot that others understand and appreciate your work; and cite your papers as a result of it. Presenting scientific work in a convincing way to appeal to a broad audience is even more important in high-impact journals that usually want to publish work that is as far-reaching as possible. This is pushing scientists more and more to shift the boundaries of their work and sometimes draw conclusions that are much more general or go beyond what is supported by the data and arguments supplied. In this lecture I will deal some aspects related to the thin line between selling and over-selling your research. I will discuss several problems that can occur when writing about science and in the process before that can result in papers where the conclusions that are drawn do not agree with what is shown in the data. This is analyzed in the context of scientific hypes (perovskite materials), hoaxes (the history of polywater) and outright fraud (the Jan Hendrik Schön affair).
2:15pm – 3:00pm
September 27 – Day 2
Session 1 – Near-Field Photonics
9:00am – 10:20am
Session Chair: Joanna Atkin
9:00am – 9:40am
Multimodal Hyperspectral Nanoimaging
Speaker: Yohannes Abate, University of Georgia, USA
Abstract: Single-layer heterostructures exhibit striking quasiparticle properties and many-body interaction effects that hold promise for a range of applications. However, their properties can be altered by intrinsic and extrinsic defects, thus diminishing their applicability. Therefore, it is of paramount importance to identify defects and understand 2D materials’ degradation over time using advanced multimodal imaging techniques. Here we implemented a liquid-phase precursor approach to synthesize 2D in-plane MoS2–WS2 heterostructures exhibiting nanoscale alloyed interfaces and map exotic interface effects during photodegradation using a combination of hyperspectral tip-enhanced photoluminescence and Raman and near-field nanoscopy. Surprisingly, 2D alloyed regions exhibit thermal and photodegradation stability providing protection against oxidation. Coupled with surface and interface strain, 2D alloy regions create stable localized potential wells that concentrate excitonic species via a charge carrier funneling effect. These results demonstrate that 2D alloys can withstand extreme degradation effects over time and could enable stable 2D device engineering.
9:40am – 10:20am
From light emission to localized chemistry with gold nanoparticles: the importance of controlling plasmon relaxation
Speaker: Celine Fiorini, Université Paris Saclay, France
Abstract: Plasmon-mediated photochemistry has now become an active area of research in nanoscience since it opens many applicative prospects from energy conversioni and photocatalysisii, to phototherapy and nanofabrication.iii,ivv Plasmon based nanoscale functionalization interestingly enables e.g. the realization of advanced hybrid nanostructures for photonics,vi,viiDespite numerous demonstrations, the exact mechanisms and main parameters driving the control of plasmon-mediated photochemical reactions remain however to be understood in detail,viii,ix Plasmon induced chemistry is directly dependent on plasmon decay which occurs through competitive relaxation processes that need to be disentangled:x (1) Photonic effects through near field electromagnetic enhancement, promoting light-matter interactions in specific nanoscale locations around the NPs, (2) Electronic effects through the transfer of hot charge carriers from the excited NP to nearby chemical species, (3) Thermal effects, through the heating resulting from the lattice thermalization following electron-phonon interactions.
I will try to discuss these different process in view of a recent systematic study of free radical nanophotopolymerization around gold nanospheres.xi I will also show that the two-photon luminescence of gold nanostructures can interestingly be taken into profit for a quantitative evaluation of the magnitude of plasmonic hot spots,xii revealing thus to be a highly valuable characterization technique.xiii
The authors gratefully thank the funding agency Agence Française pour la Recherche (ANR) for their financial support of this work (project under grants HAPPLE: ANR-12-BS10-016 and SAMIRE: ANR-13-NANO-0002).
i Plasmons for Energy Conversion, ACS Energy Lett., virtual issue (2018) – Tang et al., J. Chem. Phys. 152, 220901 (2020);
ii S. Peiris et al., Catal. Sci. Technol. 6 (2016) – Cortes et al, ACS Nano 2020, 14, 16202−16219
iii ML Brongersma et al., Nature Nano, 10, 25 (2015).
iv M. Nguyen et al., Nanoscale Horizons, 8, 8633 (2016).
v F. Kameche et al., Materials Today, 40, 38 (2020).
vi X. Zhou et al, Appl Phys Lett., 104, 023114 (2014).
vii D. Ge et al, Nature Comm. (2020)
viii C. Gruber et al., Appl Phys Lett 106, 081101 (2015) – RG Hobbs, Nanolett 17(10) 5069 (2017).- E. Kazuma et al., Science, 360, 521 (2018) and references therein.
ix Y. Dubi et al., https://pubs.rsc.org/en/Content/ArticleLanding/2020/SC/C9SC06480J#!divAbstract – Mascaretti et al., J. Appl. Phys. 128, 041101 (2020) – Rodio el al., ACS Catal. 10, 2345, (2020)
x Gellé et al., Chem. Rev., 120, 986−1041 (2020).
xi F. Kameche et al., J Phys Chem C, 125(16), 8719 (2021).
xii C. Molinaro et al., J Phys Chem C, 120, 23136 (2016) – https://arxiv.org/abs/1908.00859
xiii B. Rozic et al., ACS Nano 2017, 11, 7, 6728 – C. Molinaro et al., Phys Chem Chem Phys 20, 12295 (2018)
Session 2 – Chemical Dynamics
10:30am – 11:50am
Session Chair: Matt Beard
10:30am – 11:10am
Resolving a catalytic mechanism at an electrode surface with high time-resolution: Experimental identification of theoretical descriptors
Speaker: Tanja Cuk, University of Colorado Boulder, USA
Abstract: Catalytic mechanisms at electrode surfaces guide the development of electrochemically-controlled energy storing reactions and chemical synthesis. The intermediate steps of these mechanisms are challenging to identify experimentally, but are critical to understanding the speed, stability, and selectivity of product evolution. In the laboratory group, we employ photo-triggered vibrational and electronic spectroscopy to time-resolve the catalytic cycle at a surface, identifying meta-stable intermediates and critical transition states which connect one to another. The focus is on the highly selective water oxidation reaction at the semiconductor (SrTiO3)-aqueous interface, triggered by an ultrafast light pulse in an electrochemical cell. Here, I will summarize the work done to date by the group: the structure and dynamics of the initial intermediates that trap charge (Ti-O*- and Ti-O*+-Ti) from their picosecond birth at the surface through the next event at microseconds, suggested to be the formation of the first O-O bond of O2 evolution. There will be a focus on how time-resolving the intermediates leads to experimental identification of largely theoretical descriptors of oxygen evolution, such as the binding energy of the first meta-stable, electron-deficient oxygen intermediates (generally, M-OH*). In so doing, reaction conditions that shift equilibria become an important, independent axis to the time & energy axes of the spectroscopy. While many open questions remain, these experiments provide and benchmark the opportunity to quantify intermediates at an electrode surface and follow a heterogeneous catalytic cycle in time.
11:10am – 11:50am
Graphene Terahertz Photonics
Speaker: Mischa Bonn, MPI Polymers, Germany
Abstract: Graphene is an attractive candidate for many optoelectronic applications because of its vanishing bandgap and high carrier mobility. Ultrashort terahertz (THz) pulses interact strongly with charge carriers in graphene. On the one hand, this strong interaction allows to probe the conductivity within one layer of graphene on ultrafast timescales. On the other hand, the strong interaction can be used for the efficient heating of charge carriers, when strong THz fields are applied. This process, in turn, can be used to generate higher harmonics of THz radiation, with unprecedented efficiency: 1% of the terahertz field can be converted into its third harmonic with a single pass through the 3.3 Å thin graphene monolayer. Higher (fifth, seventh, ninth, …) harmonics can also be readily generated.
 K. J. Tielrooij, et al. Photoexcitation cascade and multiple hot-carrier generation in graphene, Nature Phys. 2013, 9, 248.
 A. Tomadin, et al., The ultrafast dynamics and conductivity of photoexcited graphene at different Fermi energies, Science Advances 2018, 4 (5), eaar5313
 Z. Mics, et al., Thermodynamic picture of ultrafast charge transport in graphene, Nature Comm. 2015, 6, 7655.
 H.A. Hafez, et al., Extremely efficient terahertz high-harmonic generation in graphene by hot Dirac fermions, Nature 2018, 561, 507.
12:00pm – 1:00pm
Lunch/Networking & Poster Session
Session 3 – Advanced Spectroscopic Techniques for Materials Discovery
1:00pm – 3:00pm
Session Chair: Aram Amassian
1:00pm – 1:40pm
Mapping Atomic Motions with Ultrabright Electrons: Fundamental Space-Time Limit to Imaging Chemistry
Speaker: R. J. Dwayne Miller, University of Toronto, Canada
Abstract: One of the long sought objectives in science has been to watch atomic motions on the primary timescales governing structural transitions. From a chemistry perspective, this capability would give a direct observation of reaction forces and probe the central unifying concept of transition states that links chemistry to biology. To achieve this objective, there are not only extraordinary requirements for simultaneous spatial-temporal resolution but equally important, due to sample limitations, also one on source brightness. With the development of ultrabright electrons capable of literally lighting up atomic motions, this experiment has been realized (Siwick et al Science 2003) and efforts accelerated with the onset of XFELs (Miller, Science 2014). A number of different chemical reactions will be discussed from electrocyclization with conserved stereochemistry, intermolecular electron transfer for organic systems, metal to metal electron transfer, to the direct observation of a bimolecular collision and bond formation in condensed phase for the classic I3- system, in a process analogous to a molecular Newton’s cradle. These studies have discovered that these high dimensional problems, order 3N (N number of atoms in the reaction volume) representing the number of degrees of freedom in the system, distilled down to atomic projections along a few principle reaction coordinates. The specific details depend on the spatial resolution to these motions, for which <.01 Å changes in atomic position (less than the background thermal motion) has now been achieved on the 100 fs timescale. Without any detailed analysis, the key large-amplitude modes can be identified by eye from the molecular movies. This reduction in dimensionality appears to be general, arising from the very strong anharmonicity of the many body potential in the barrier crossing region. We now are beginning to see the underlying physics for the generalized reaction mechanisms that have been empirically discovered over time. The “magic of chemistry” is this enormous reduction in dimensionality in the barrier crossing region that ultimately makes chemical concepts transferrable. How far can this reductionist view be extended with respect to complexity? This talk will also address the prospect of imaging single molecule trajectories and possibility of quantum tomography to go beyond the classical picture of structural dynamics to retrieve nuclear probability distributions.
1:40pm – 2:20pm
High-throughput discovery of upconverting and photon avalanching nanoparticles for lasing and sub-diffraction imaging
Speaker: Emory Chan, Lawrence Berkeley National Laboratory, USA
Abstract: Lanthanide-doped nanomaterials exhibit complex photophysical dynamics that give rise to photon upconversion, which can be leveraged for applications in optoelectronics, in vivo sensing, and imaging through tissue. I will discuss the high-throughput, robot-assisted discovery and application of new classes of upconverting nanoparticles, including materials that utilize photon avalanche and energy looping mechanisms to non-linearly amplify excited state populations. These mechanisms, which can be initiated with 1064 nm light in thulium-doped NaYF4 nanoparticles, allow “energy-looping nanoparticles” (ELNPs) to be imaged through millimeters of brain tissue. By coupling ELNPs to the whispering gallery modes of polystyrene microspheres, the resonators achieve sufficient gain to exhibit continuous-wave, anti-Stokes lasing that is stable for hours at room temperature. These microlasers operate even in complex biological media such as serum and through tissue-mimicking phantoms. We reduce the dimensions and thresholds of upconverting nanoparticle lasers by tuning their compositions, shells, and by coupling them to plasmonic arrays. By tuning the doping and photophysics of ELNPs, we demonstrated first observation of single photon avalanching nanoparticles, whose giant nonlinear optical responses allow imaging with ~70 nm resolution, far below the diffraction limit.
2:20pm – 3:00pm
Self-driving laboratories for light-emitting organic materials
Speaker: Alán Aspuru-Guzik, University of Toronto, Canada
Abstract: In this talk, I will describe our group’s interdisciplinary research towards the acceleration of molecular discovery. We focus on the discovery of small-molecule-based materials such as solid-state organic light emitting diodes and organic lasers I will discuss artificial intelligence models for the generation of molecular candidates with particular properties, forward-synthetic space prediction methods that are amenable to automation, and Bayesian-optimization driven experimentation. In particular, for the design of organic lasers, we have designed a Chemspeed synthesis machine/HPLC-MS/laser characterization self-driving lab. I will discuss the synergies and opportunities with small-molecule drug discovery as well as process optimization. Several of the tools we have developed have been translated to these fields.
September 28 – Day 3
Session 4 – Quantum Information Science
9:00am – 10:20am
Session Chair: Ashley Arcidiacono
9:20am – 9:40am
Influence of Vibronic Coupling on Ultrafast Singlet Fission and Symmetry-breaking Charge Transfer
Speaker: Michael Wasielewski, Northwestern University, USA
Abstract: Chromophore aggregates are capable of a wide variety of excited-state dynamics that are potentially of great use in opto-electronic devices based on organic molecules. For example, singlet fission, the process by which a singlet exciton is down converted into two triplet excitons, holds promise for extending the efficiency of solar cells, while other processes, such as symmetry-breaking charge transfer, where the excited dimer charge separates into a radical ion pair, can be both a trap and potentially useful in devices, depending on the context.
These seemingly disparate phenomenon can be described within the same, unifying framework, where each case can be represented as one point in continuum of mixed states. The coherent mixed state is observed experimentally, and it collapses to each of the limiting cases under well-defined conditions. This framework is especially useful in demonstrating the connections between these different states so that we can determine the factors that control their evolution and may ultimately guide the state mixtures to the product state of choice.
We utilize covalent dimers and trimers to precisely arrange the chromophores in rigid, well-defined geometries to systematically study the factors that determine the degree of coherent state mixing and its fate. We interrogate these dynamics with transient absorption spectroscopy from the UV continuously into the mid-infrared, along with time-resolved stimulated Raman and 2D electronic spectroscopies to build detailed molecular level picture of the system dynamics.
9:40am – 10:20am
Chemistry for the Second Quantum Revolution
Speaker: Danna Freedman, Massachusetts Institute of Technology, USA
Abstract: Quantum Information Science (QIS) is an emerging field with the potential to transform disciplines ranging from communication to sensing. Creating the next generation of materials for QIS requires minute control over structure and function. The same atomistic structural precision inherent to synthetic chemistry that enables the design of new drugs can be harnessed towards the challenge of creating new systems for QIS. By exploiting the reproducibility and structural precision of synthetic chemistry we can control the coherence properties of molecules, create two qubit systems, and imbue molecules with the same optical read-out of spin properties exhibited by state-of-the-art systems such as the anionic nitrogen vacancy pair defect in diamond. A chemical approach to quantum information will be presented.
10:20am – 10:30am
Session 5 – Biophotonics
10:30am – 12:30pm
Session Chair: Chantal Andraud
10:30am – 11:10am
Light-harvesting nanoparticles based on dyes with efficient energy transfer for amplified biosensing
Speaker: Andrey Klymchenko, Strasbourg University, France
Abstract: Assembling dyes into nanoparticles (NPs) can address the fundamental limitation of brightness of single organic dyes, important for fluorescence sensing and imaging. However, high dye concentration inside NPs leads to aggregation-caused quenching (ACQ). Moreover, how to ensure efficient energy transfer in this large dye ensemble, which would allow generating nanoprobes where a single molecular recognition at the particle surface would switch emission of hundreds of dyes? In order to prevent ACQ, we developed a methodology based on bulky counterions, which serve as spacers between organic dyes in polymeric NPs. Using this concept, we obtained polymeric NPs of small size that are >100-fold brighter than semiconductor quantum dots. At thigh dye loading, we observed a unique phenomenon – fast dye-dye communication, so that >100 dyes inside NPs can undergo complete ON/OFF switching.[2a] This collective dye behavior enabled preparation of giant light-harvesting nanoantenna that amplified up to 1000-fold emission of single FRET acceptor dyes and allowed first single-molecule detection in ambient light. By grafting nucleic acids to their surface, we obtained FRET-based biosensors with brightness of ~3000 dyes,[3a] compatible with smartphone-based sensing, and sensitive to a single copy of nucleic acids. These nanoantennas constitute an ultrabright platform for preparation of light-harvesting devices and FRET-based biosensors.
ERC consolidator grant BrightSens 648528 is acknowledged for the financial support.
 A. Reisch, A. S. Klymchenko, Small 2016, 12, 1968.
 a) A. Reisch, P. Didier, L. Richert, S. Oncul, Y. Arntz, Y. Mély, A. S. Klymchenko, Nature Communications 2014, 5, 4089; b) B. Andreiuk, A. Reisch, E. Bernhardt, A. S. Klymchenko, Chemistry – An Asian Journal 2019, 14, 836.
 a) N. Melnychuk, A. S. Klymchenko, Journal of the American Chemical Society 2018, 140, 10856; b) A. Reisch, K. Trofymchuk, A. Runser, G. Fleith, M. Rawiso, A. S. Klymchenko, ACS Applied Materials & Interfaces 2017, 9, 43030.
 K. Trofymchuk, A. Reisch, P. Didier, F. Fras, P. Gilliot, Y. Mely, A. S. Klymchenko, Nature Photonics 2017, 11, 657.
 C. Severi, N. Melnychuk, A. S. Klymchenko, Biosensors & Bioelectronics 2020, 168.
 N. Melnychuk, S. Egloff, A. Runser, A. Reisch, A. S. Klymchenko, Angewandte Chemie International Edition 2020, 59, 6811.
11:10am – 11:50am
Exposing the Dynamics of Living Bacterial Membranes with Second Harmonic Generation
Speaker: Tessa Calhoun, University of Tennessee, Knoxville, USA
Abstract: Biological membranes are the gatekeepers for living function and hence antibiotic response. These complex environments, however, are challenging to probe given their heterogeneity across multiple length scales and dynamic evolution. The study of bacterial membranes is complicated further by their high anionic lipid composition and the cell’s small size. An area of increasing interest in these systems is the role of domains within the membranes that have been implicated in antibiotic resistance. Second harmonic generation (SHG) is a nonlinear spectroscopic technique that can uniquely sense the movement of small molecules within living bacterial membranes, including flipping between bilayer leaflets and association with more rigid microenvironments. Herein I will discuss how this sensitivity of SHG extends to detect differences arising from molecular structure and bacterial species. Further, we can directly monitor how the introduction of exogenous domain disruptors impacts the behavior of small molecule dynamics within the membranes. Overall, these capabilities provide new directions to better assess the impact of membrane domains in bacteria.
11:50am – 12:30pm
Linear and Non-Linear Optical Studies of Myelin Doped with Carbon Nanodots
Speaker: Katarzyna Matczyszyn, Wroclaw University of Science and Technology, Poland
Abstract: Myelin is one of the crucial components of the nerve structure exhibiting ability to create liquid crystalline arrangement [1-3]. The analysis of its structure raise considerable attention due to its crucial role in transmission of nerve impulses and unsolved questions about causes of demyelinating disorders . Therefore studies on the formation of multilayered structures composed of lipids, ionic or nonionic surfactants in aqueous solution and markers are conducted [5-6] as it may help to investigate stability of the lamellar phase under various external factors, such as increased humidity or temperature . On the other hand, there is still a need of the new markers which would not interfere with the LC structure itself but would bring more information about its inner organization. We decided to synthesise and analyse the interactions of the biocompatible carbon nanodots with the synthetic myelin structure to use it as an effective fluorescent marker with possible excitation both by the visible and infrared light. The mesophases were observed in samples made of phospholipids above their phase transition temperature. The experiments were performed on 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), which forms the liquid crystalline phase at ambient temperature, doped with triangular carbon nanodots . The polarized light microscope equipped with a retardation plate allowed to detect the existence of mesophases and to provide information about the orientational order of lipids within myelin structure (Fig.1).
We also observed the myelin structures by two-photon excited fluorescence microscopy (2PEF). The shape of myelin structure was clearly depicted on a map showing the intensity of two-photon excited luminescence (2PEL). The emission spectra taken from inside the myelin structure, confirmed that a detected signal is related to 2PEL of carbon nanodots in phospholipid matrix (Fig.2). Taking advantage of 2PEF we showed that the excitation of carbon nanodots in multilamellar tubes can be shifted from visible spectrum to the biological window which provides e.g. deeper penetration depth into biological tissues and lower phototoxicity .
The authors would like to thank Prof. Ivan Smalyukh for his valuable contributions to their research into lyotropic myelin structure and Prof. Lucyna Firlej for the discussions on the carbon nanodots.
 M. Mitov, “Cholesteric liquid crystals in living matter,” Soft Matter, vol. 13, no. 23, pp. 4176–4209, 2017, doi: 10.1039/c7sm00384f.
 I. Dierking, A. F. Neto, “Novel Trends in Lyotropic Liquid Crystals,” Crystals, 10, 604, 2020, doi: 10.3390/cryst10070604
 A. I. Boullerne, “The history of myelin,” Exp. Neurol., vol. 283, pp. 431–445, 2016, doi: 10.1016/j.expneurol.2016.06.005.
 L. M. Silverman and G. C. Bullock, “Molecular Diagnosis of Human Disease,” Mol. Pathol. Mol. Basis Hum. Dis., vol. 9780123744, pp. 591–604, 2009, doi: 10.1016/B978-0-12-374419-7.00028-7.
 D. Benkowska-Biernacka, I. I. Smalyukh, and K. Matczyszyn, “Morphology of Lyotropic Myelin Figures Stained with a Fluorescent Dye,” J. Phys. Chem. B, vol. 124, no. 52, pp. 11974–11979, 2020, doi: 10.1021/acs.jpcb.0c08907.
 J. R. Huang, Y. C. Cheng, H. J. Huang, and H. P. Chiang, “Confocal mapping of myelin figures with micro-Raman spectroscopy,” Appl. Phys. A Mater. Sci. Process., vol. 124, no. 1, pp. 1–6, 2018, doi: 10.1007/s00339-017-1450-z.
 R. Mosaviani, A. R. Moradi, and L. Tayebi, “Effect of humidity on liquid-crystalline myelin figure growth using digital holographic microscopy,” Mater. Lett., vol. 173, pp. 162–166, 2016, doi: 10.1016/j.matlet.2016.03.023.
 F. Yuan et al., Engineering triangular carbon quantum dots with unprecedented narrow bandwidth emission for multicolored LEDs , Nature Communications, 9, 2249, 2018, doi: 10.1038/s41467-018-04635-5
 E. Hemmer, A. Benayas, F. Légaré, and F. Vetrone, “Exploiting the biological windows: Current perspectives on fluorescent bioprobes emitting above 1000 nm,” Nanoscale Horizons, vol. 1, no. 3, pp. 168–184, 2016, doi: 10.1039/c5nh00073d.
12:30pm – 1:30pm
Lunch / Networking & Poster Session
Session 6 – Contributed Talks
1:30pm – 2:45pm
Session Chair: Chantal Andraud
These presenters are selected from the submitted abstracts.
2:45pm – 3:00pm
Speaker: Phil Castellano