An official website of the United States government
Two-dimensional (2D) transition metal carbides and nitrides, commonly known as MXenes, are a class of 2D materials with high free carrier densities, making them highly attractive candidates for plasmonic 2D materials. In this study, we use multiphoton photoemission electron microscopy (nP-PEEM) to directly image the plasmonic near fields of multilayers of the prototypical MXene, Ti3C2Tx, with mixed surface terminations (Tx = F, O, and OH). Photon-energy dependentnP-PEEM reveals a dispersive surface plasmon polariton between 1.4 and 1.9 electron volts on MXene flakes thicker than 30 nanometers and waveguide modes above 1.9 electron volts. Combining experiments with finite-difference time-domain simulations, we reveal the emergence of a visible surface plasmon polariton in MXenes, opening avenues for exploration of polaritonic phenomena in MXenes in the visible portion of the electromagnetic spectrum.
more »
« less
Correlation-driven attosecond photoemission delay in the plasmonic excitation of C 60 fullerene
Extreme light confinement in plasmonic nanosystems enables novel applications in photonics, sensor technology, energy harvesting, biology, and quantum information processing. Fullerenes represent an extreme case for nanoplasmonics: They are subnanometer carbon-based molecules showing high-energy and ultrabroad plasmon resonances; however, the fundamental mechanisms driving the plasmonic response and the corresponding collective electron dynamics are still elusive. Here, we uncover the dominant role of electron correlations in the dynamics of the giant plasmon resonance (GPR) of the subnanometer system C60by using attosecond photoemission chronoscopy. We find a characteristic photoemission delay of up to about 300 attoseconds that is purely induced by coherent large-scale electron correlations in the plasmonic potential. These results provide insights into the nature of the plasmon resonances in subnanometer systems and open perspectives for advancing nanoplasmonic applications.
more »
« less
- PAR ID:
- 10626418
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- American Association for the Advancement of Science
- Date Published:
- Journal Name:
- Science Advances
- Volume:
- 11
- Issue:
- 7
- ISSN:
- 2375-2548
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
In metal nanostructures under illumination, multiple different processes can drive current flow, and in an opencircuit configuration some of these processes lead to the production of open-circuit photovoltages. Structures that have plasmonic resonances at the illumination wavelength can have enhanced photovoltage response, due to both increased interactions with the incident radiation field, and processes made possible through the dynamics of the plasmon excitations themselves. Here we review photovoltage response driven by thermoelectric effects in continuous metal nanowires and photovoltage response driven by hot electron production and tunneling. We discuss the prospects for enhancing and quantifying hot electron generation and response via the combination of local plasmonic resonances and propagating surface plasmon polaritons.more » « less
-
Abstract Plasmon decay is believed to play an essential role in inducing hot carrier transfer at the interfaces between plasmonic nanoparticles and semiconductor surfaces. In this work, we employ real-time time-dependent density functional theory (RT-TDDFT) simulation in the Wannier gauge to gain quantum-mechanical insights into the nonlinear dynamics of the plasmon decay in the Ag20nanoparticle at a semiconductor surface. The first-principles simulations show that the plasmon decay is more than two times faster when the Ag20nanoparticle is adsorbed on a hydrogen-terminated Si(111) surface, taking place within 100 femtoseconds of the plasmon excitation. Hot carrier transfer across the interface is observed as the plasmon decay takes place, and nearly 30% of holes are generated deep in the valence band of the semiconductor surface. The use of Wannier gauge in RT-TDDFT simulation is particularly convenient for gaining quantum-mechanical insights into non-equilibrium electron dynamics in complex heterogeneous systems.more » « less
-
Aluminum nanocrystals offer a promising platform for plasmonic photocatalysis, yet a detailed understanding of their electron dynamics and consequent photocatalytic performance has been challenging thus far due to computational limitations. Here, we employ density functional tight-binding methods (DFTB) to investigate the optical properties and H2 dissociation dynamics of Al nanocrystals with varying sizes and geometries. Our real-time simulations reveal that Al’s unique free-electron nature enables efficient light-matter interactions and rapid electronic thermalization. Cubic and octahedral nanocrystals ranging from 0.5 to 4.5 nm exhibit size-dependent plasmon resonances in the UV, with distinct spectral features arising from the particle geometry and electronic structure. By simulating H2 dissociation near Al nanocrystals, we demonstrate that hot electrons generated through plasmon excitation can overcome the molecule’s strong chemical bond within tens of femtoseconds. The laser intensity threshold is comparable to previous reports for Ag nanocrystals, though significantly lower than that of Au. Notably, the dipolar plasmon mode demonstrates higher efficiency for this reaction than the localized interband transition for particles at these sizes. Taken together, this work provides mechanistic insights into plasmon-driven catalysis and showcases DFTB’s capability to study quantum plasmonics at unprecedented length and time scales.more » « less
-
We apply ultrafast nanoscale microscopic imaging and analytical modeling to investigate the coherent field and spin textures of dual plasmonic vortices as a means to design the momentum flow, and spin topology by interaction of their gyrating fields. The ultrafast laser normal incidence illumination by circularly polarized light of two vortex generator structures with variable separations in silver films launches structured surface plasmon polariton fields. Two distinct primary vortices and a third emergent vortex, generated by interaction of the primary vortices and tunable by design of their separation, form through the spin–orbit interaction of light. The gyration of plasmon fields and the consequent vectorial Poynting momentum flow is imaged with sub-optical cycle phase and spatial resolution by interferometric time-resolved two-photon photoemission electron microscopy (ITR-2P-PEEM). The ultrafast imaging and analytical modeling of the interaction of the dual plasmonic vortices examines the nanoscale control of plasmon spin topology and momentum driven transport.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1126/sciadv.ads0494
