Hypersound attenuation and phase velocities in evaporated polycrystalline films of silver, copper and constantan between 1 and 24 GHz

Lehr, B.; Ulrich, H.; Weis, O.

doi:10.1007/bf02026424

Cited by 18 publications

(2 citation statements)

References 7 publications

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“…(The Ta layer was not included, for simplicity.) In the simulations intrinsic material ultrasonic attenuation is neglected; at the frequencies concerned this is a very good approximation for the distances of propagation (∼100 µm) in question and for the materials concerned [38][39][40]. Figure 2(a) shows a simulated image for out-of-plane surface displacement (denoted by u(r, t)) at approximately 19.6 ns after excitation of the a = 4 µm grating.…”

Section: Time-domain Simulationsmentioning

confidence: 99%

Point source in a phononic grating: stop bands give rise to phonon-focusing caustics

et al. 2012

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We use locally-excited gigahertz surface phonon wavepackets in microscopic line structures of different pitches to reveal profound anisotropy in the radiation pattern of a point source in a grating. Time-domain data obtained by an ultrafast optical imaging technique and by numerical simulations are Fourier transformed to obtain frequency-filtered real-space acoustic field patterns and k-space phononic band structure. The numerically-obtained k-space images are processed to reveal an intriguing double-horn structure in the lowest-order group-velocity surface, which explains the observed non-propagation sectors bounded by caustics, noted at frequencies above the bottom of the first stop band. We account for these phonon-focusing effects, analogous to collimation effects previously observed in two-and three-dimensional lattices, with a simple

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Section: Time-domain Simulationsmentioning

confidence: 99%

Point source in a phononic grating: stop bands give rise to phonon-focusing caustics

et al. 2012

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“…In terms of coupling processes that have been used to excite magnetic films and piezoelectric crystals, the presence of the sample in the electromagnetic field to excite acoustic waves/ phonons has been sufficient to achieve generation in the hypersonic GHz range. [24][25][26][27] In contrast, acoustic sensor measurements seem to rely on electrical signals transmitted through wires to metal electrodes in order to excite the acoustics. This theme has continued with surface acoustic waves devices, which obtain higher frequencies of operation, [28][29][30] but these devices are still impractical for providing hypersonic transverse waves that can concentrate at the molecular interface.…”

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confidence: 99%

Hypersonic evanescent waves generated with a planar spiral coil

Stevenson

Araya-Kleinsteuber

Sethi

et al. 2003

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A planar spiral coil has been used to induce hypersonic evanescent waves in a quartz substrate with the unique ability to focus the acoustic wave down onto the chemical recognition layer. These special sensing conditions were achieved by investigating the application of a radio frequency current to a coaxial waveguide and spiral coil, so that wideband repeating electrical resonance conditions could be established over the MHz to GHz frequency range. At a selected operating frequency of 1.09 GHz, the evanescent wave depth of a quartz crystal hypersonic resonance is reduced to 17 nm, minimising unwanted coupling to the bulk fluid. Verification of the validity of the hypersonic resonance was carried out by characterising the system electrically and acoustically: Impedance calculations of the combined coil and coaxial waveguide demonstrated an excellent fit to the measured data, although above 400 MHz a transition zone was identified where unwanted impedance is parasitic of the coil influence efficiency, so the signal-to-noise ratio is reduced from 3000 to 300. Acoustic quartz crystal resonances at intervals of precisely 13.2138 MHz spacing, from the 6.6 MHz ultrasonic range and onto the desired hypersonic range above 1 GHz, were incrementally detected. Q factor measurements demonstrated that reductions in energy lost from the resonator to the fluid interface were consistent with the anticipated shrinkage of the evanescent wave with increasing operating frequency. Amplitude and frequency reduction in contact with a glucose solution was demonstrated at 1.09 GHz. The complex physical conditions arising at the solid-liquid interface under hypersonic entrainment are discussed with respect to acceleration induced slippage, rupture, longitudinal and shear radiation and multiphase relaxation affects.

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Experiments with Movable Hypersound Beams

Weis

1986

Phonon Scattering in Condensed Matter V

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Hypersound attenuation and phase velocities in evaporated polycrystalline films of silver, copper and constantan between 1 and 24 GHz

Cited by 18 publications

References 7 publications

Point source in a phononic grating: stop bands give rise to phonon-focusing caustics

Point source in a phononic grating: stop bands give rise to phonon-focusing caustics

Hypersonic evanescent waves generated with a planar spiral coil

Experiments with Movable Hypersound Beams

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