Cherenkov radiation generated in hexagonal boron nitride using extremely low-energy electrons

AbstractCherenkov radiation (CR) is the electromagnetic shockwaves generated by the uniform motion of charged particles at a velocity exceeding the phase velocity of light in a given medium. In the Reststrahlen bands of hexagonal boron nitride (hBN), hyperbolic phonon polaritons (HPPs) are generated owing to the coupling between mid-infrared electromagnetic waves and strong anisotropic lattice vibrations. This study theoretically and numerically investigates the generation of volume CR based on HPPs in hBN with super-large wavevectors. Results reveal that CR can be generated using free electrons with an extremely low kinetic energy of 1 eV—two orders of magnitude lower than that reported in extant studies. The findings of this investigation provide new insights into significantly reducing the electron energy required for CR generation and potentially open new research avenues in the fields of CR and HPP.

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Dynamics of optical vortices in 2D materials

10.21203/rs.3.rs-1234204/v1 ◽

2022 ◽

Author(s):

Yaniv Kurman ◽

Raphael Dahan ◽

Hanan Herzig Sheinfux ◽

Gilles Rosolen ◽

Eli Janzen ◽

...

Keyword(s):

Electromagnetic Waves ◽

Hexagonal Boron Nitride ◽

2D Materials ◽

Condensed Matter ◽

Pair Creation ◽

Optical Vortices ◽

Free Electrons ◽

2D Material ◽

Transmission Electron ◽

Planar Geometries

Abstract Optical vortices in planar geometries are a universal wave phenomenon, where electromagnetic waves possess topologically protected integer values of orbital angular momentum (OAM). The conservation of OAM governs their dynamics, including their rules of creation and annihilation. However, such dynamics remained so far beyond experimental reach. Here, we present a first observation of creation and annihilation of optical vortex pairs. The vortices conserve their combined OAM during pair creation/annihilation events and determine the field profile throughout their motion between these events. We utilize free electrons in an ultrafast transmission electron microscope to probe the vortices, which appear in the form of phonon polaritons in the 2D material hexagonal boron nitride. These results provide the first observation of optical vortices in any 2D material, which were predicted but never observed. Our findings promote future investigation of vortices in 2D materials and their use for chiral plasmonics, toward the control of selection rules in light-matter interactions and the creation of optical simulators of phase transitions in condensed matter physics.

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Tunable Cherenkov Radiation of Phonon Polaritons in Silver Nanowire/Hexagonal Boron Nitride Heterostructures

Nano Letters ◽

10.1021/acs.nanolett.0c00419 ◽

2020 ◽

Vol 20 (4) ◽

pp. 2770-2777 ◽

Cited By ~ 1

Author(s):

Yiran Zhang ◽

Cheng Hu ◽

Bosai Lyu ◽

Hongyuan Li ◽

Zhe Ying ◽

...

Keyword(s):

Boron Nitride ◽

Cherenkov Radiation ◽

Hexagonal Boron Nitride ◽

Silver Nanowire ◽

Phonon Polaritons

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Optical lattice vibrations in monolayer hexagonal boron nitride from macroscopic equations

Journal of Physics Condensed Matter ◽

10.1088/1361-648x/ab4f5a ◽

2019 ◽

Vol 32 (6) ◽

pp. 065304 ◽

Cited By ~ 1

Author(s):

J-Z Zhang

Keyword(s):

Boron Nitride ◽

Optical Lattice ◽

Hexagonal Boron Nitride ◽

Lattice Vibrations ◽

Macroscopic Equations

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NUCLEATE POOL BOILING AND CONDENSATION HEAT TRANSFER CHARACTERISTICS OF HEXAGONAL BORON NITRIDE/DICHLOROMETHANE NANOFLUID

Heat Transfer Research ◽

10.1615/heattransres.2020034308 ◽

2020 ◽

Vol 51 (11) ◽

pp. 1043-1059

Author(s):

Erdem Çiftçi ◽

Adnan Sözen

Keyword(s):

Heat Transfer ◽

Boron Nitride ◽

Hexagonal Boron Nitride ◽

Pool Boiling ◽

Condensation Heat Transfer ◽

Nucleate Pool Boiling ◽

Heat Transfer Characteristics ◽

Transfer Characteristics

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Marcus-Hush Theory Revealed by Electron Tunneling Through Hexagonal Boron Nitride

10.26434/chemrxiv.9275135.v1 ◽

2019 ◽

Author(s):

Matěj Velický ◽

Sheng Hu ◽

Colin R. Woods ◽

Peter S. Toth ◽

Viktor Zólyomi ◽

...

Keyword(s):

Electron Transfer ◽

Boron Nitride ◽

Electron Tunneling ◽

Hexagonal Boron Nitride ◽

Large Body ◽

Liquid Solution ◽

Limiting Current ◽

Electron Transfer Rate Constant ◽

Electrochemical Parameters ◽

Voltammetric Measurements

Marcus-Hush theory of electron transfer is one of the pillars of modern electrochemistry with a large body of supporting experimental evidence presented to date. However, some predictions, such as the electrochemical behavior at microdisk electrodes, remain unverified. Herein, we present a study of electron tunneling across a hexagonal boron nitride barrier between a graphite electrode and redox levels in a liquid solution. This was achieved by the fabrication of microdisk electrodes with a typical diameter of 5 µm. Analysis of voltammetric measurements, using two common redox mediators, yielded several electrochemical parameters, including the electron transfer rate constant, limiting current, and transfer coefficient. They show a significant departure from the Butler-Volmer behavior in a clear manifestation of the Marcus-Hush theory of electron transfer. In addition, our system provides a novel experimental platform, which could be applied to address a number of scientific problems such as identification of reaction mechanisms, surface modification, or long-range electron transfer.

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