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Nanoshells under pressure

Nanoshells under pressure. Pressure gauges with a golden layer. 21 July 2012. Overview. Nanoshells DAC Mie & Hybridization theory Nanoshells (NS) under pressure Coated Nanoshells (CNS) Experiments & outview. Nanoshells: G ifts in a golden wrapper. Dielectric core & metallic shell

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Nanoshells under pressure

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  1. Nanoshells underpressure Pressure gauges with a golden layer 21 July2012

  2. Overview Nanoshells DAC Mie & Hybridization theory Nanoshells (NS) under pressure Coated Nanoshells (CNS) Experiments & outview

  3. Nanoshells:Gifts in a golden wrapper • Dielectriccore & metallic shell • Tunable Au SiO2 Halas N., Optics & Photonics News, p. 26 (August 2002)

  4. Nanoshells:Gifts in a golden wrapper • Applications • Biosensing • Cancer ablation • Targetedmedication • Plasmonics • …

  5. DiamondAnvilCell (DAC) • Small pressure on large surface • DAC usesdiamonds: Table Culet

  6. DiamondAnvilCell (DAC) • Create high pressures in betweentodiamonds • In between the diamondsthere is a pressure medium: • Helium • Hydrogen • Neon • …

  7. Rubies as pressure sensor • Use the spectrum of rubiestomeasure the pressure • The R1and R2lineswill shift underpressure • Needstobecalibrated APS: http://www.aps.anl.gov/News/APS_News/Content/APS_NEWS_20080311B.php

  8. Rubies as pressure sensor • Unfortunatly the calibration is not perfect • Interference with diamond resonances Silveraet. al. Phys. stat. sol. (b) 1, 460-467 (2007)

  9. Nanoshells as pressuregauge • Use the optical response of nanoshells in stead of rubies • Why? • NS are smaller • Tunable • …

  10. Mie-theory • We use Mie-theorytocalculate the spectrum of nanoshells: Rc = 60 nm Rs = 75 nm

  11. Hybridization model • Nanoshells = cavity +sphere • Solve the Lagrangian of the electron sea which is depicted as an incompresible fluid. Prodan, et. al., Science, 302, 419 (2003)

  12. Mie vs. Hybridization • Mie solves exactly for given dielectric function, but needs further numerical manipulation. • Hybridization is not exact, but gives analytical solutions:

  13. Nanoshells underpressure • Compression of NS • Radii change: Rc(P) andRs(P) • Electrondensity changes ne(P) Vinet equation: J. Geophys. Res. 92, 9319 (1987)

  14. Nanoshells underpressure • Relative cross section:

  15. Lookinggood! • We calculate the peak shift:

  16. Pressure media • The nanoshell is not in vacuum, but inside a pressure medium. H2 SiO2 Ne He

  17. Notsogood • The shift changes direction • Andseemsto stop for He and Ne

  18. The coated nanoshell (CNS) Au SiO2 • Add an extra layer: • Will shield the influence of the medium • But leaves the compressiblity • But how thick?

  19. The coated nanoshell • A thicklayer is needed!

  20. Theoreticalpredictions • Averageresolutionfor CNS: 0,90 nm / GPa • Rubies: 0,36 nm/ GPa • Advantages: • Nanoshells canbetunedto right frequency band • Are smaller andneedlessdensity • Disadvantage: • Callibration is stillneeded

  21. Experiments Page left blank intentionally

  22. Outview • Experimentalverification • Finetuning of theory • Heating • Use as biosensor • Sensing of metallic hydrogen

  23. Nanoshells underpressure Questions? Published: N. Van den Broeck et al. JAP 110, 114318 (2011) 21 July2012

  24. Extra: waarom geen vol SiO2 bolletje? R = 200 nm R1 = 60 nm R2 = 75 nm R3 = 200 nm

  25. Extra: waarom geen Au kern en dikke SiO2 schil? R1 = 75 nm R2 = 200 nm R1 = 60 nm R2 = 75 nm R3 = 200 nm

  26. Extra: waarom geen Au kern en dikke SiO2 schil?

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