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Article ; Online: Tunable Hypersonic Bandgap Formation in Anisotropic Crystals of Dumbbell Nanoparticles.

Kim, Hojin / Gueddida, Abdellatif / Wang, Zuyuan / Djafari-Rouhani, Bahram / Fytas, George / Furst, Eric M

ACS nano

2023 Volume 17, Issue 19, Page(s) 19224–19231

Abstract: Phononic materials exhibit mechanical properties that alter the propagation of acoustic waves and are widely useful for metamaterials. To fabricate acoustic materials with phononic bandgaps, colloidal nanoparticles and their assemblies allow access to ... ...

Abstract	Phononic materials exhibit mechanical properties that alter the propagation of acoustic waves and are widely useful for metamaterials. To fabricate acoustic materials with phononic bandgaps, colloidal nanoparticles and their assemblies allow access to various crystallinities in the submicrometer scale. We fabricated anisotropic crystals with dumbbell-shaped nanoparticles via field-directed self-assembly. Brillouin light spectroscopy detected the formation of direction-dependent hypersonic phononic bandgaps that scale with the lattice parameters. In addition, the local resonances of the constituent nanoparticles enable metamaterial behavior by opening hybridization gaps in disordered structures. Unexpectedly, this bandgap frequency is robust to changes in the dumbbell aspect ratio. Overall, this study provides a structure-property relationship for designing anisotropic phononic materials with targeted phononic bandgaps.
Language	English
Publishing date	2023-09-27
Publishing country	United States
Document type	Journal Article
ISSN	1936-086X
ISSN (online)	1936-086X
DOI	10.1021/acsnano.3c05750
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Phononic Crystal Made of Silicon Ridges on a Membrane for Liquid Sensing.

Gueddida, Abdellatif / Zhang, Victor / Carpentier, Laurent / Bonhomme, Jérémy / Bonello, Bernard / Pennec, Yan / Djafari-Rouhani, Bahram

Sensors (Basel, Switzerland)

2023 Volume 23, Issue 4

Abstract: We propose the design of a phononic crystal to sense the acoustic properties of a liquid that is constituted by an array of silicon ridges on a membrane. In contrast to other concepts, the ridges are immersed in the liquid. The introduction of a suitable ...

Abstract	We propose the design of a phononic crystal to sense the acoustic properties of a liquid that is constituted by an array of silicon ridges on a membrane. In contrast to other concepts, the ridges are immersed in the liquid. The introduction of a suitable cavity in the periodic array gives rise to a confined defect mode with high localization in the cavity region and strong solid-liquid interaction, which make it sensitive to the acoustic properties of the liquid. By using a finite element method simulation, we theoretically study the transmission and cavity excitation of an incident flexural wave of the membrane. The observation of the vibrations of this mode can be achieved either outside the area of the phononic crystal or just above the cavity. We discuss the existence of the resonant modes, as well as its quality factor and sensitivity to liquid properties as a function of the geometrical parameters. The performance of the proposed sensor has then been tested to detect the variation in NaI concentration in a NaI-water mixture.
Language	English
Publishing date	2023-02-13
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2052857-7
ISSN	1424-8220 ; 1424-8220
ISSN (online)	1424-8220
ISSN	1424-8220
DOI	10.3390/s23042080
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Article: Optomechanic Coupling in Ag Polymer Nanocomposite Films

Noual, Adnane / Kang, Eunsoo / Maji, Tanmoy / Gkikas, Manos / Djafari-Rouhani, Bahram / Fytas, George

Journal of physical chemistry. 2021 June 30, v. 125, no. 27

2021

Abstract: Particle vibrational spectroscopy has emerged as a new tool for the measurement of elasticity, glass transition, and interactions at a nanoscale. For colloid-based materials, however, the weakly localized particle resonances in a fluid or solid medium ... ...

Abstract	Particle vibrational spectroscopy has emerged as a new tool for the measurement of elasticity, glass transition, and interactions at a nanoscale. For colloid-based materials, however, the weakly localized particle resonances in a fluid or solid medium renders their detection difficult. The strong amplification of the inelastic light scattering near surface plasmon resonance of metallic nanoparticles (NPs) allowed not only the detection of single NP eigenvibrations but also the interparticle interaction effects on the acoustic vibrations of NPs mediated by strong optomechanical coupling. The “rattling” and quadrupolar modes of Ag/polymer and polymer-grafted Ag NPs with different diameters in their assemblies are probed by Brillouin light spectroscopy (BLS). We present thorough theoretical 3D calculations for anisotropic Ag elasticity to quantify the frequency and intensity of the “rattling” mode and hence its BLS activity for different interparticle separations and matrix rigidity. Theoretically, a liquidlike environment, e.g., poly(isobutylene) (PIB) does not support rattling vibration of Ag dimers but unexpectedly hardening of the extremely confined graft melt renders both activation of the former and a frequency blue shift of the fundamental quadrupolar mode in the grafted nanoparticle Ag@PIB film.
Keywords	acoustics ; anisotropy ; glass transition ; polymer nanocomposites ; polymers ; spectroscopy ; surface plasmon resonance ; vibration
Language	English
Dates of publication	2021-0630
Size	p. 14854-14864.
Publishing place	American Chemical Society
Document type	Article
ISSN	1932-7455
DOI	10.1021/acs.jpcc.1c04549
Database	NAL-Catalogue (AGRICOLA)

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Article: Graphene-Based One-Dimensional Terahertz Phononic Crystal: Band Structures and Surface Modes.

Quotane, Ilyasse / El Boudouti, El Houssaine / Djafari-Rouhani, Bahram

Nanomaterials (Basel, Switzerland)

2020 Volume 10, Issue 11

Abstract: In this paper, we provide a theoretical and numerical study of the acoustic properties of infinite and semi-infinite superlattices made out of graphene-semiconductor bilayers. In addition to the band structure, we emphasize the existence and behavior of ... ...

Abstract	In this paper, we provide a theoretical and numerical study of the acoustic properties of infinite and semi-infinite superlattices made out of graphene-semiconductor bilayers. In addition to the band structure, we emphasize the existence and behavior of localized and resonant acoustic modes associated with the free surface of such structures. These modes are polarized in the sagittal plane, defined by the incident wavevector and the normal to the layers. The surface modes are obtained from the peaks of the density of states, either inside the bulk bands or inside the minigaps of the superlattice. In these structures, the two directions of vibrations (longitudinal and transverse) are coupled giving rise to two bulk bands associated with the two polarizations of the waves. The creation of the free surface of the superlattice induces true surface localized modes inside the terahertz acoustic forbidden gaps, but also pseudo-surface modes which appear as well-defined resonances inside the allowed bands of the superlattice. Despite the low thickness of the graphene layer, and though graphene is a gapless material, when it is inserted periodically in a semiconductor, it allows the opening of wide gaps for all values of the wave vector k// (parallel to the interfaces). Numerical illustrations of the band structures and surface modes are given for graphene-Si superlattices, and the surface layer can be either Si or graphene. These surface acoustic modes can be used to realize liquid or bio-sensors graphene-based phononic crystal operating in the THz frequency domain.
Language	English
Publishing date	2020-11-05
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2662255-5
ISSN	2079-4991
ISSN	2079-4991
DOI	10.3390/nano10112205
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Optomechanic Coupling in Ag Polymer Nanocomposite Films.

Noual, Adnane / Kang, Eunsoo / Maji, Tanmoy / Gkikas, Manos / Djafari-Rouhani, Bahram / Fytas, George

The journal of physical chemistry. C, Nanomaterials and interfaces

2021 Volume 125, Issue 27, Page(s) 14854–14864

Abstract	Particle vibrational spectroscopy has emerged as a new tool for the measurement of elasticity, glass transition, and interactions at a nanoscale. For colloid-based materials, however, the weakly localized particle resonances in a fluid or solid medium renders their detection difficult. The strong amplification of the inelastic light scattering near surface plasmon resonance of metallic nanoparticles (NPs) allowed not only the detection of single NP eigenvibrations but also the interparticle interaction effects on the acoustic vibrations of NPs mediated by strong optomechanical coupling. The "rattling" and quadrupolar modes of Ag/polymer and polymer-grafted Ag NPs with different diameters in their assemblies are probed by Brillouin light spectroscopy (BLS). We present thorough theoretical 3D calculations for anisotropic Ag elasticity to quantify the frequency and intensity of the "rattling" mode and hence its BLS activity for different interparticle separations and matrix rigidity. Theoretically, a liquidlike environment, e.g., poly(isobutylene) (PIB) does not support rattling vibration of Ag dimers but unexpectedly hardening of the extremely confined graft melt renders both activation of the former and a frequency blue shift of the fundamental quadrupolar mode in the grafted nanoparticle Ag@PIB film.
Language	English
Publishing date	2021-06-30
Publishing country	United States
Document type	Journal Article
ISSN	1932-7447
ISSN	1932-7447
DOI	10.1021/acs.jpcc.1c04549
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Article ; Online: Quantization of Acoustic Modes in Dumbbell Nanoparticles.

Wang, Zuyuan / Kim, Hojin / Secchi, Maria / Montagna, Maurizio / Furst, Eric M / Djafari-Rouhani, Bahram / Fytas, George

Physical review letters

2022 Volume 128, Issue 4, Page(s) 48003

Abstract: The vibrational eigenmodes of dumbbell-shaped polystyrene nanoparticles are recorded by Brillouin light spectroscopy (BLS), and the full experimental spectra are calculated theoretically. Different from spheres with a degeneracy of (2l+1), with l being ... ...

Abstract	The vibrational eigenmodes of dumbbell-shaped polystyrene nanoparticles are recorded by Brillouin light spectroscopy (BLS), and the full experimental spectra are calculated theoretically. Different from spheres with a degeneracy of (2l+1), with l being the angular momentum quantum number, the eigenmodes of dumbbells are either singly or doubly degenerate owing to their axial symmetry. The BLS spectrum reveals a new, low-frequency peak, which is attributed to the out-of-phase vibration of the two lobes of the dumbbell. The quantization of acoustic modes in these molecule-shaped dumbbell particles evolves from the primary colloidal spheres as the separation between the two lobes increases.
Language	English
Publishing date	2022-02-11
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.128.048003
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Article ; Online: Elastic stubbed metamaterial plate with torsional resonances.

Wang, Wei / Bonello, Bernard / Djafari-Rouhani, Bahram / Pennec, Yan / Zhao, Jinfeng

Ultrasonics

2020 Volume 106, Page(s) 106142

Abstract: We report on a new mechanism involving the torsional resonance of stubs to achieve the negative effective shear modulus of an elastic metamaterial plate. Combined with a mechanism to create a negative mass density, we develop a general method to set up ... ...

Abstract	We report on a new mechanism involving the torsional resonance of stubs to achieve the negative effective shear modulus of an elastic metamaterial plate. Combined with a mechanism to create a negative mass density, we develop a general method to set up and enlarge a shear-horizontal-polarized double-negative branch in the elastic metamaterial plate with stubs on both sides. We explore the capabilities of this structure for polarization filtering, mode conversion and abnormal refraction. It is shown that, this metamaterial plate behaves divergently against the polarization of incident waves propagating along ΓX direction in a square lattice crystal: it behaves as a double-negative system for zero-order shear horizontal (SH
Language	English
Publishing date	2020-04-09
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	200839-7
ISSN	1874-9968 ; 0041-624X
ISSN (online)	1874-9968
ISSN	0041-624X
DOI	10.1016/j.ultras.2020.106142
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Article ; Online: Physics of surface vibrational resonances: pillared phononic crystals, metamaterials, and metasurfaces.

Jin, Yabin / Pennec, Yan / Bonello, Bernard / Honarvar, Hossein / Dobrzynski, Leonard / Djafari-Rouhani, Bahram / Hussein, Mahmoud I

Reports on progress in physics. Physical Society (Great Britain)

2021 Volume 84, Issue 8

Abstract: The introduction of engineered resonance phenomena on surfaces has opened a new frontier in surface science and technology. Pillared phononic crystals, metamaterials, and metasurfaces are an emerging class of artificial structured media, featuring ... ...

Abstract	The introduction of engineered resonance phenomena on surfaces has opened a new frontier in surface science and technology. Pillared phononic crystals, metamaterials, and metasurfaces are an emerging class of artificial structured media, featuring surfaces that consist of pillars-or branching substructures-standing on a plate or a substrate. A pillared phononic crystal exhibits Bragg band gaps, while a pillared metamaterial may feature both Bragg band gaps and local resonance hybridization band gaps. These two band-gap phenomena, along with other unique wave dispersion characteristics, have been exploited for a variety of applications spanning a range of length scales and covering multiple disciplines in applied physics and engineering, particularly in elastodynamics and acoustics. The intrinsic placement of pillars on a semi-infinite surface-yielding a metasurface-has similarly provided new avenues for the control and manipulation of wave propagation. Classical waves are admitted in pillared media, including Lamb waves in plates and Rayleigh and Love waves along the surfaces of substrates, ranging in frequency from hertz to several gigahertz. With the presence of the pillars, these waves couple with surface resonances richly creating new phenomena and properties in the subwavelength regime and in some applications at higher frequencies as well. At the nanoscale, it was shown that atomic-scale resonances-stemming from nanopillars-alter the fundamental nature of conductive thermal transport by reducing the group velocities and generating mode localizations across the entire spectrum of the constituent material well into the terahertz regime. In this article, we first overview the history and development of pillared materials, then provide a detailed synopsis of a selection of key research topics that involve the utilization of pillars or similar branching substructures in different contexts. Finally, we conclude by providing a short summary and some perspectives on the state of the field and its promise for further future development.
Language	English
Publishing date	2021-09-06
Publishing country	England
Document type	Journal Article ; Review
ZDB-ID	205657-4
ISSN	1361-6633 ; 0034-4885
ISSN (online)	1361-6633
ISSN	0034-4885
DOI	10.1088/1361-6633/abdab8
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Article ; Online: Polymer photonic crystal membrane for thermo-regulating textile.

Assaf, Salim / Boutghatin, Mohamed / Pennec, Yan / Thomy, Vincent / Korovin, Alexander / Treizebre, Anthony / Carette, Michèle / Akjouj, Abdellatif / Djafari-Rouhani, Bahram

Scientific reports

2020 Volume 10, Issue 1, Page(s) 9855

Abstract: We study numerically the absorption and scattering properties of a polymer photonic membrane to thermoregulate the human body microclimate which corresponds to the area between the skin and a textile. We first show that the structuration of the absorbing ...

Abstract	We study numerically the absorption and scattering properties of a polymer photonic membrane to thermoregulate the human body microclimate which corresponds to the area between the skin and a textile. We first show that the structuration of the absorbing photonic membrane with air holes leads to a modulation of the optical spectrum in the Mid-Infrared range. Indeed, we show that the membrane is able to modulate the transmission amplitude by 28% in benefit or deficit of both the absorption and reflection. We then studied the thermal balance between the human body and the surrounding environment through the photonic membrane. We found that, compared to a regular membrane, the photonic crystal structure behaves as a heating component that offers the possibility to reduce the temperature of the room up to +1 °C. The membrane is flexible, low cost, 3D-printable, free of metallic particles, and can easily be added to usual textiles.
Language	English
Publishing date	2020-06-17
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-020-66731-1
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Impact of SiO

Boutghatin, Mohamed / Assaf, Salim / Pennec, Yan / Carette, Michèle / Thomy, Vincent / Akjouj, Abdellatif / Djafari Rouhani, Bahram

Nanomaterials (Basel, Switzerland)

2020 Volume 10, Issue 10

Abstract: Keeping the human body in a thermal comfort state inside a room has become a challenge in recent years. While the most common strategy is to heat buildings, it requires a lot of energy. Reducing this energy consumption will have positive impacts, both ... ...

Abstract	Keeping the human body in a thermal comfort state inside a room has become a challenge in recent years. While the most common strategy is to heat buildings, it requires a lot of energy. Reducing this energy consumption will have positive impacts, both economically and environmentally. We propose here to act directly on the personal thermal heating of the human body, by modulating the absorption and transmission properties of a synthetic polymer membrane in the mid-infrared (MIR). We show numerically that 5% SiO
Language	English
Publishing date	2020-10-04
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2662255-5
ISSN	2079-4991
ISSN	2079-4991
DOI	10.3390/nano10101968
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