Effect of local environment in resonant domains of polydisperse plasmonic nanoparticle aggregates on optodynamic processes in pulsed laser fields

Interactions of pulsed laser radiation with resonance domains of multiparticle colloidal aggregates having an increasingly complex local environment are studied via an optodynamic model. The model is applied to the simplest configurations, such as single particles, dimers, and trimers consisting of mono- and polydisperse Ag nanoparticles. We analyze how the local environment and the associated local feld enhancement by surrounding particles affect the optodynamic processes in domains, including their photomodification and optical properties.

Review of the Book “Magnetooptical Spectroscopy of the Rare-Earth Compounds: Development and Application”

This book reviews and provides numerous theoretical calculations for the first time relevant to the optics and magneto-optics of the trivalent rare earth ions (RE3+) and their compounds. The RE3+ have unique spectroscopic properties that make them exceptionally attractive to both scientists, who probe the fundamental properties of these systems, and engineers, who develop these systems into photonic devices eagerly marketed in expanded technologies. Magneto-optical effects in compounds doped with RE3+ have been studied since the dawn of modern physics and have had a profound impact on their development in terms of practical opto-electronic devices. The authors of this new, exciting, and fresh text are world famous in this field, with over 150 years of experience in developing important theoretical and experimental contributions and over fifty years of more than 500 refereed publications in this field in the Soviet Union and the United States. They offer both a conceptual description of magneto-optical phenomena, as well as clear, detailed theoretical development published for the first time of many of the phenomena only briefly addressed in the literature. The book is based on the author’s original work in theoretical and experimental investigations in magneto-optics. Numerous graphs and simple examples model the phenomena described in the text, making it a highly desirable treatise for scientists beginning their studies in the field of magneto-optics.

Restructuring of plasmonic nanoparticle aggregates with arbitrary particle size distribution in pulsed laser fields

We have studied processes of interaction of pulsed laser radiation with resonant groups of plasmonic nanoparticles（resonant domains） in large colloidal nanoparticle aggregates having different interparticle gaps and particle size distributions.These processes are responsible for the origin of nonlinear optical effects and photochromic reactions in multiparticle aggregates.To describe photo-induced transformations in resonant domains and alterations in their absorption spectra remaining after the pulse action,we introduce the factor of spectral photomodification.Based on calculation of changes in thermodynamic,mechanical,and optical characteristics of the domains,the histograms of the spectrum photomodification factor have been obtained for various interparticle gaps,an average particle size,and the degree of polydispersity.Variations in spectra have been analyzed depending on the intensity of laser radiation and various combinations of size characteristics of domains.The obtained results can be used to predict manifestation of photochromic effects in composite materials containing different plasmonic nanoparticle aggregates in pulsed laser fields.

Spin States of 2D Nanocomposites of Ni and V Nanoclusters on Hexagonal h-BN, BC_3 and Graphene

Atomic and electronic structures of adsorbed nickel and vanadium atoms and nanoclusters （Nin and Vn, n = 1-10） on hexagonal h-BN and BC3 lattices were studied using DFT PBE/PBC/PW （Perdew-Burke- Ernzerhof potential of density functional theory/periodic boundary conditions/plane wave basis set） technique. For the sake of comparison the structure and properties of the same nanoclusters deposited on pristine graphene were calculated as well. It was found that for all types of supports an increase of n from 1 to 10 leaded to decrease of coordination types from 776 to r/2 and 771. The h-BN- and BC3-based nanocomposites were characterized by high （up to 18 μ for Ni10/BC3） magnetic moments of the nanoclusters and featured by positive binding energies. The graphene-based nanocomposites revealed energetic stability and, in general, lower magnetic moments per unit cell. The direct potential energy barriers for migration of Ni η2/η21 and η6/η6 types of dimers on graphene were low （10.9-28.9 kJ/mol） with high reverse barriers for η6/η6 dimers, which favored dynamically equilibrated Ni clusterization on graphene.

Merging bound states in the continuum in an open acoustic resonator

Bound states in the continuum(BICs)are perfectly localized resonances despite embedding in the continuum spectrum.However,an isolated BIC is very sensitive to the structure perturbation.Here,we report merging acoustic BICs in a single open resonator,robust against the structure perturbation.We find that both symmetry-protected BIC and Friedrich-Wintgen BIC are sustained in a single coupled waveguide-resonator system.By varying the height and length of the resonator,these two BICs move toward each other and merge into a single one at a critical dimension.Compared to an individual BIC,the merged BIC is robust against fabrication error because its Q-factor is proportional toΔL^(−4),whereΔL embodies the structure perturbation.The essence of this extraordinary phenomenon is perfectly explained by the two-and three-level approximations of the effective non-Hermitian Hamiltonian.Finally,we present direct experimental demonstrations of the moving and merging of BICs in a coupled 3D waveguide-resonator,which are evidenced by the vanishing of the linewidth of Fano resonance in the transmission spectra.Our results may find exciting applications in designing high-quality acoustic sources,sensors and filters.