Alexandra Boehmke

King's College London

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Jie Gu

Fudan University

Vinod M. Menon

The Graduate Center, CUNY

Rian Koots

Stony Brook University

Jeremy J. Baumberg

University of Cambridge

Daniel Rhodes

University of Wisconsin–Madison

Lutz Waldecker

RWTH Aachen University

Archana Raja

Government of the United States of America

Edina Rosta

University College London

Tony F. Heinz

Stanford University

Biswanath Chakraborty

Indian Institute of Technology Jammu

Cooperative Institutions

University of Cambridge

King's College London

University College London

City University of New York

City College of New York

Columbia University

The Graduate Center, CUNY

Donostia International Physics Center

University of Warwick

University of California, San Diego

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Optical probes of molecules as nano-mechanical switches

Nature Communications (2020)

Dean Kos Giuliana Di Martino Alexandra Boehmke Bart de Nijs Dénes Berta

Abstract Molecular electronics promises a new generation of ultralow-energy information technologies, based around functional molecular junctions. Here, we report optical probing that exploits a gold nanoparticle in a plasmonic nanocavity geometry used as one terminal of a well-defined molecular junction, deposited as a self-assembled molecular monolayer on flat gold. A conductive transparent cantilever electrically contacts individual nanoparticles while maintaining optical access to the molecular junction. Optical readout of molecular structure in the junction reveals ultralow-energy switching of ∼50 zJ, from a nano-electromechanical torsion spring at the single molecule level. Real-time Raman measurements show these electronic device characteristics are directly affected by this molecular torsion, which can be explained using a simple circuit model based on junction capacitances, confirmed by density functional theory calculations. This nanomechanical degree of freedom is normally invisible and ignored in electrical transport measurements but is vital to the design and exploitation of molecules as quantum-coherent electronic nanodevices.

Molecular Electronics

Molecular switch

10.1038/s41467-020-19703-y

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Citations (29)

Nonlinear Interaction of Rydberg Exciton-Polaritons in Two-Dimensional WSe 2

Conference on Lasers and Electro-Optics (2019)

Jie Gu Lutz Waldecker Daniel Rhodes Alexandra Boehmke Archana Raja

We demonstrate the formation of Rydberg exciton-polaritons in monolayer WSe 2 embedded in a microcavity and their 10X enhanced nonlinear interaction strength compared to the 1S exciton-polaritons owing to their larger size. © 2019 The Author(s)

Exciton-polaritons

Nanophotonics

10.23919/cleo.2019.8749761

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Citations (1)

Nonlinear Interaction of Rydberg Exciton-Polaritons in Two-Dimensional WSe2

Conference on Lasers and Electro-Optics (2019)

Jie Gu Lutz Waldecker Daniel Rhodes Alexandra Boehmke Archana Raja

We demonstrate the formation of Rydberg exciton-polaritons in monolayer WSe2 embedded in a microcavity and their 10X enhanced nonlinear interaction strength compared to the 1S exciton-polaritons owing to their larger size.

Exciton-polaritons

10.1364/cleo_qels.2019.fw3m.5

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Citations (2)

Guiding of visible photons at the ångström thickness limit

Nature Nanotechnology (2019)

Xingwang Zhang Chawina De-Eknamkul Jie Gu Alexandra Boehmke Vinod M. Menon

Angstrom

10.1038/s41565-019-0519-6

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Citations (67)

Room temperature dynamical control and electroluminescence from microcavity polaritons in monolayer transitional metal dichalcogenides

Bulletin of the American Physical Society (2019)

Biswanath Chakraborty Jie Gu Zheng Sun Mandeep Khatoniar Rezlind Bushati

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Observation of Rydberg exciton-polaritons in 2D transition metal dichalcogenides

Conference on Lasers and Electro-Optics (2018)

Jie Gu Alexandra Boehmke Rian Koots Vinod M. Menon

We report the strong coupling between Rydberg excitons (2S state) and cavity photons in monolayer WSe2 with the Rabi splitting of ∼ 20meV at 77K. Rydberg exciton-polaritons are crucial for solid state quantum non-linear optics.

Exciton-polaritons

10.1364/cleo_qels.2018.fm2f.6

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Uncovering low-frequency vibrations in surface-enhanced Raman of organic molecules

arXiv (Cornell University) (2024)

Alexandra Boehmke Roberto A. Boto Eoin Elliot Bart de Nijs Rubén Esteban

Accessing the terahertz (THz) spectral domain through surface-enhanced Raman spectroscopy (SERS) is challenging and opens up the study of low-frequency molecular and electronic excitations. Compared to direct THz probing of heterogenous ensembles, the extreme plasmonic confinement of visible light to deep sub-wavelength scales allows the study of hundreds or even single molecules. We show that self-assembled molecular monolayers of a set of simple aromatic thiols confined inside single-particle plasmonic nanocavities can be distinguished by their low-wavenumber spectral peaks below 200 cm-1, after removal of a bosonic inelastic contribution and an exponential background from the spectrum Developing environment-dependent density-functional-theory simulations of the metal-molecule configuration enables the assignment and classification of their THz vibrations as well as the identification of intermolecular coupling effects and of the influence of the gold surface configuration Furthermore, we show dramatically narrower THz SERS spectra from individual molecules at picocavities, which indicates the possibility to study intrinsic vibrational properties beyond inhomogeneous broadening further supporting the key role of local environment.

Organic molecules

10.48550/arxiv.2407.04102

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Molecular Screening for Terahertz Detection with Machine-Learning-Based Methods

Physical Review X (2021)

Zsuzsanna Koczor-Benda Alexandra Boehmke Angelos Xomalis Rakesh Arul Charlie Readman

The molecular requirements are explored for achieving efficient signal up-conversion in a recently developed technique for terahertz (THz) detection based on molecular optomechanics. We discuss which molecular and spectroscopic properties are most important for predicting efficient THz detection and outline a computational approach based on quantum-chemistry and machine-learning methods for calculating these properties. We validate this approach by bulk and surface-enhanced Raman scattering and infrared absorption measurements. We develop a virtual screening methodology performed on databases of millions of commercially available compounds. Quantum-chemistry calculations for about 3000 compounds are complemented by machine-learning methods to predict applicability of 93 000 organic molecules for detection. Training is performed on vibrational spectroscopic properties based on absorption and Raman scattering intensities. Our top molecules have conversion intensity two orders of magnitude higher than an average molecule from the database. We also discuss how other properties like molecular shape and self-assembling properties influence the detection efficiency. We identify molecular moieties whose presence in the molecules indicates high activity for THz detection and show an example where a simple modification of a frequently used self-assembling compound can enhance activity 85-fold. The capabilities of our screening method are demonstrated on narrow-band and broadband detection examples, and its possible applications in surface-enhanced spectroscopy are also discussed.Received 9 April 2021Revised 10 August 2021Accepted 7 September 2021DOI:https://doi.org/10.1103/PhysRevX.11.041035Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)TechniquesDensity functional theoryElectronic structureHigh-throughput calculationsMachine learningRaman spectroscopySurface-enhanced Raman spectroscopyTerahertz spectroscopyAtomic, Molecular & OpticalCondensed Matter, Materials & Applied Physics

10.1103/physrevx.11.041035

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Citations (5)

Interacting Rydberg Exciton-Polaritons in Two-Dimensional Transition Metal Dichalcogenides

Bulletin of the American Physical Society (2019)

Jie Gu Lutz Waldecker Daniel Rhodes Alexandra Boehmke Rian Koots

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Control of Strong Light–Matter Interaction in Monolayer WS₂ through Electric Field Gating

Nano Letters (2018)

Biswanath Chakraborty Jie Gu Zheng Sun Mandeep Khatoniar Rezlind Bushati

Strong light-matter coupling results in the formation of half-light half-matter quasiparticles that take on the desirable properties of both systems such as small mass and large interactions. Controlling this coupling strength in real-time is highly desirable due to the large change in optical properties such as reflectivity that can be induced in strongly coupled systems. Here we demonstrate modulation of strong exciton–photon coupling in a monolayer WS2 through electric field induced gating at room temperature. The device consists of a WS2 field effect transistor embedded inside a microcavity structure which transitions from strong to weak coupling when the monolayer WS2 becomes more n-type under gating. This transition occurs due to the reduction in oscillator strength of the excitons arising from decreased Coulomb interaction in the presence of electrostatically induced free carriers. The possibility to electrically modulate a solid state system at room temperature from strong to weak coupling is highly desirable for realizing low energy optoelectronic switches and modulators operating both in quantum and classical regimes.

Oscillator strength

10.1021/acs.nanolett.8b02932

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Citations (90)