Thirty Years Ago!. At the Max Planck CdTe Resonant Brillouin Scattering

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<ul><li><p>Thirty Years Ago!</p></li><li><p>At the Max PlanckCdTeResonant Brillouin Scattering</p></li><li><p>Membrane Acoustics: Nanostructures to biological tissues Supported layers standing resonancesSiON/GaAs; ZnSe/GaAsFreestanding NanomembranesSiNSiN/PolymerPatterned nanowires</p><p>Cornea and eye lens </p></li><li><p>Longitudinal Standing ModesSiO3N4/ GaAsZnSe/ GaAs</p></li><li><p>Organ Pipe Modes</p><p>d=3/4, f=3V/4d,Second harmonicd=, f=V/dSecond harmonic</p></li><li><p>Scattering IntensityElasto-Optic Contributions Film + SubstrateBortolani, Marvin, Nizzoli, Santoro J. Phys. C. 16, 1757 (1983)E-O</p></li><li><p>Scattering Intensity</p></li><li><p>ZnSe/GaAs: BLS Intensity</p></li><li><p>Freestanding membranesUltra-light weight Robust, pliable, flexible electronicsMechanical/ elastic propertiesProximity of surfaces ~ phonon wavelengthsLattice vibrations modifiedIncreased phonon relaxation ratesNano-scale heat transport; Quantized thermal conductance Consequence on electron transportComposite hard-soft (inorganic-polymer) membranesPhonon isolation Lithography on soft layerNano-wires/ lines</p></li><li><p>Freestanding Si3N4 membraneLSM, TSM, Dilational, Flexural Modes</p></li><li><p>Freestanding Si3N4-PMMA bilayer nano-membranes</p></li><li><p>PMMA/SiN: dispersion </p></li><li><p>Nanowires </p></li><li><p>Nano-wire DispersionOdd parityEven parityResonant Ultrasound Spectroscopy (Migliori)</p></li><li><p>In-plane Dispersion</p></li><li><p>Mode Profiles2TSMEdge type1TSM1TSMm= 0TSMq1= qx = m/w,q2= qy = 0</p></li><li><p>Mode ProfilesFinite q</p></li><li><p>Human LensSoft outer cortex, stiff inner nucleusTransition between stiff nucleus to soft cortex results in mode doubletNo change in frequency and bulk modulus with age (B = 2 2/4n2).</p><p>Heys KR, et.al Molecular Vision (2004)</p></li><li><p>Bovine Lens and CorneaProbe intact bovine eye globe, power ~5mW.Frequency (bulk modulus) profile mapped through axial depth of eye globe.Corneal modulus (BLS) excellent agreement with ultrasonics on same location Cortex-nucleus transition in bovine lens not seen.Corneal and lenticular thickness, distance between cornea and lens measured.Probe fibril structure in cornea?Bulk Modulus:Human Lens: 3.7 GPa, Bovine Lens: 4.1 GPa,Bovine Cornea: 2.6 GPa </p><p>Mission, G. Ophthal. Physiol. Opt. 2007 27: 256-264. </p></li><li><p>ConclusionsBLS of elasticity on nanoscale structuresStanding wave modes (LSM, TSM) distinct role of ripple and e-o contributionsFlexural and Dilational modesMode confinement across width and height of rectangular wires role of sidewalls in trench structuresCorneal and Lens studies non-invasive probe with potential clinical relevance</p><p>******</p></li></ul>