Simultaneous Occurrence of Structure-Directed and Particle-Resonance-Induced Phononic Gaps in Colloidal Films

Abstract

We report on the observation of two hypersonic phononic gaps of different nature in three-dimensional colloidal films of nanospheres using Brillouin light scattering. One is a Bragg gap occurring at the edge of the first Brillouin zone along a high-symmetry crystal direction. The other is a hybridization gap in crystalline and amorphous films, originating from the interaction of the band of quadrupole particle eigenmodes with the acoustic effective-medium band, and its frequency position compares well with the computed lowest eigenfrequency. Structural disorder eliminates the Bragg gap, while the hybridization gap is robust.

Surface Patterning with Colloidal Monolayers

“…However, especially surfactant-free emulsion polymerization is priced for the high monodispersity [29,183] of the resulting latex particles. These find applications where high precision colloidal crystals are needed, most prominently in the fields of photonics, [184][185] phononics, [186][187] and lithography. [5,136,188] As the symmetry and order of the nanoparticles arrays to be produced from the metal-complex containing colloids crucially depends on the uniformity of the colloids, surfactant-free emulsion polymerization was applied to incorporate different metal complexes in order to produce colloids with a narrow size distribution.…”

Soft silicone rubber in phononic structures: Correct elastic moduli

“…[1][2][3] In recent years, some effort has been taken to expand the concept of phononic effects beyond simple Bragg interference, [3][4][5] including the clever design of hybrid structures consisting of materials of very different elastic properties.…”

Band structure of cavity-type hypersonic phononic crystals fabricated by femtosecond laser-induced two-photon polymerization

“…3(a)) represented by a sum of Lorentzian lines and their peak position defines the phonon frequencies at a given wavenumber q. 5,7,12,14 In the present hPnC, phonons were probed with wave vector q ¼ k s -k i (Fig. 2(d)) lying along the CX and CM (Fig.…”

“…1,4 Since the first realization of a hypersonic phononic band gap, 5 the design, fabrication, and characterization of 1D, 2D, and 3D hypersonic phononic crystals (hPnC) have been the subject of intensive research. [6][7][8][9][10][11][12][13][14] However, the fabrication of such periodic crystals is still a technological challenge, since the control over the periodicity for various 3D architectures on the sub micrometer scale is necessary. Electron and focused ion-beam lithographic techniques are powerful in producing 2D GHz phononic structures in opaque media.…”

“…Electron and focused ion-beam lithographic techniques are powerful in producing 2D GHz phononic structures in opaque media. 15,16 Selfassembly by vertical lifting deposition 5,7 and holographic interference lithography 6,17,18 have enabled the fabrication of 2D hPnC in transparent polymeric media with limited 3D architectures. To realize true multiple 3D nano-and micro-structured structures in photosensitive polymeric media, direct laser writing technology based on the multi-photon absorption processes such as two-photon polymerization (2PP) is a very attractive option.…”