1,668 research outputs found
Tunable strong plasmon-exciton coupling based on borophene and deep subwavelength perovskite grating
Two-dimensional materials support deeply confined and tunable plasmonic
modes, which have great potential for achieving device miniaturization and
flexible manipulation. In this paper, we propose a diffraction-unlimited system
composed of borophene layer and perovskite grating to investigate the strong
coupling between the borophene guiding plasmon (BGP) and perovskite exciton
(PE) mode. The resonant energy of BGP mode could be electrically tuned to match
the energy of PE mode, and a remarkable Rabi splitting is attained under
zero-detuning condition. The splitting energy could reach 230 meV due to the
strong field enhancement provided by BGP mode. Consequently, an active
reflective phase modulation with 1.76{\pi} range is achieved by dynamically
manipulating the detuning. Furthermore, by increasing the distance between the
borophene layer and perovskite grating, a parity-time symmetry breaking could
be observed with the vanished energy splitting. Our results deepen the
understanding of light-matter interaction at the sub-wavelength scale and
provide a guideline for designing active plasmonic devices.Comment: 9 pages, 4 figure
Active formation of Friedrich-Wintgen bound states in the continuum in dielectric dimerized grating borophene heterostructure
The Friedrich-Wintgen bound state in the continuum (FW BIC) provides a unique
approach for achieving high quality factor (Q-factor) resonance, which has
attracted wide attention and promoted the development of various applications.
However, the FW BIC is usually considered as accident BIC resulting from the
continuous parameters tuning, and a systematic approach to generate the FW BIC
is still lacking. To address this, a method of actively forming FW BIC by
matching the damping rate and resonance frequency of the coupling mode is
proposed. As a proof-of-principle example, we propose a dielectric dimerized
grating borophene heterostructure that generates a FW BIC near the commercially
important communication wavelength. The coupling system comprises an
electrically tunable borophene plasmon mode and a BIC supported by a dielectric
dimer grating that can be attributed to the Brillouin zone folding. More
interestingly, the BIC can be excited by the localized borophene plasmon (LBP)
mode through near-field coupling as LBP mode can be considered as the dipole
source. The interaction between them can further form the FW BIC, and support
electromagnetically induced transparency (EIT)-like with maximum group index up
to 2043, indicating its great potential for slow light applications. Our
results provide a promising strategy and theoretical support for the generation
of FW BIC in active plasmonic optical devices
A triclinic polymorph with Z = 3 of N,N′-bis(2-pyridyl)oxamide
The asymmetric unit of the title compound, C12H10N4O2, contains three half-molecules. Each half-molecule is completed by crystallographic inversion symmetry. The title compound, (I), is a polymorph of the structure, (II), reported by Hsu & Chen [Eur. J. Inorg. Chem. (2004), 1488–1493]. In the original report, the compound crystallized in the tetragonal space group P
21c (Z = 8), whereas the structure reported here is triclinic (P
, Z = 3). In both forms, each oxamide molecule is almost planar (with maximum deviations are 0.266 and 0.166 Å) and the O atoms are trans oriented. The principal difference between the two forms lies in the different hydrogen-bonding patterns. In (I), two N—H⋯O and one N—H⋯N hydrogen bonds link the molecules, forming a two-dimensional network, whereas in (II) there are no classical hydrogen bonds to O atoms and only weak C—H⋯O interactions are found along with rings of N—H⋯N bonds
Stator vibration of generator under SAERISC faults
This paper analyzes the stator vibration response under static air-gap eccentricity and rotor inter-turn short circuit composite faults (SAERISC). The detailed formula of the magnetic force on stator is firstly deduced. Then the finite element simulations and practical experiments are taken to investigate the stator vibration response. It’s shown that, 1st to 4th stator vibrations will be produced. The development of the short circuit will decrease the 2nd vibration but increase the 4th vibration, while the increment of the eccentricity will increase the 1st to 4th vibrations at the same time
tert-Butyl N-(5-bromo-1H-imidazo[4,5-b]pyridin-2-ylmethyl)carbamate
In the molecule of the title compound, C12H15BrN4O2, the imidazole and pyridine rings are strictly coplanar [maximum deviation 0.006 (3) Å]. In the crystal structure, molecules are linked into chains running parallel to the a axis by intermolecular N—H⋯O hydrogen bonds. Centrosymmetrically related chains are further connected by N—H⋯N hydrogen-bonding interactions to form a two-dimensional layer structure parallel to the ab plane
Brominated Selinane Sesquiterpenes from the Marine Brown Alga Dictyopteris divaricata
Two new brominated selinane sesquiterpenes, 1-bromoselin-4(14),11-diene (1) and 9-bromoselin-4(14),11-diene (2), one known cadinane sesquiterpene, cadalene (3), and four known selinane sesquiterpenes, α-selinene (4), β-selinene (5), β-dictyopterol (6), and cyperusol C (7), were isolated from a sample of marine brown alga Dictyopteris divaricata collected off the coast of Yantai (China). Their structures were established by detailed MS and NMR spectroscopic analysis, as well as comparison with literature data
N′-(2-Bromo-5-hydroxy-4-methoxybenzylidene)-3,5-dihydroxybenzohydrazide methanol monosolvate
In the crystal structure of the title compound, C15H13BrN2O5·CH3OH, the methanol solvent molecule links symmetry-related molecules through O—H⋯O and N—H⋯O hydrogen bonds. Further intermolecular O—H⋯O hydrogen bonds link symmetry-related molecules, leading to the formation of a three-dimensional network. Two of the H atoms involved in hydrogen bonding are disordered. The dihedral angle between the rings is 5.64 (14)°
- …