Nanoshells under pressure
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Transcript of Nanoshells under pressure
Nanoschillen onder druk
Nanoshells under pressurePressure gauges with a golden layer
21 July 2012
1NanoshellsDACMie & Hybridization theoryNanoshells (NS) under pressureCoated Nanoshells (CNS)Experiments & outview
Overview2
3Nanoshells:Gifts in a golden wrapperDielectric core & metallic shellTunableAuSiO2
Halas N., Optics & Photonics News, p. 26 (August 2002)
ApplicationsBiosensingCancer ablationTargeted medicationPlasmonicsNanoshells:Gifts in a golden wrapper4
5Diamond Anvil Cell (DAC)
TableCulet
Omdat Diamanten hard en onsamendrukbaar zijn. En omdat diamanten doorzichtig zijn, waardoor optische metingen mogelijk zijn.56Diamond Anvil Cell (DAC)Create high pressures in between to diamondsIn between the diamonds there is a pressure medium:HeliumHydrogenNeon
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Use the spectrum of rubies to measure the pressureThe R1 and R2 lines will shift under pressureNeeds to becalibrated7Rubies as pressure sensor
APS: http://www.aps.anl.gov/News/APS_News/Content/APS_NEWS_20080311B.php
8Rubies as pressure sensorUnfortunatly the calibration is not perfect
Interference with diamond resonances
Silvera et. al. Phys. stat. sol. (b) 1, 460-467 (2007)Men kalibreert de robijnen via metalen (waarbij men via de roosterparameter zeer nauwkeurig de druk kan bepalen). Echter, zoals uit de figuur blijkt is de kalibratie afhankelijk van het gekozen metaal, wat eigenlijk wil zeggen dat er toch een onnauwkeurigheid zit op de drukmeting8
Use the optical response of nanoshells in stead of rubiesWhy?NS are smallerTunable9Nanoshells as pressure gauge
Extras: voor opwarming, als extra biosensor, we kunnen ze mixen, 9We use Mie-theory to calculate the spectrum of nanoshells:10Mie-theory
Rc = 60 nmRs = 75 nm11Hybridization model
Prodan, et. al., Science, 302, 419 (2003) Nanoshells = cavity +sphere
Solve the Lagrangian of the electron sea which is depicted as an incompresible fluid.
12Mie vs. HybridizationMie solves exactly for given dielectric function, but needs further numerical manipulation.Hybridization is not exact, but gives analytical solutions:
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Compression of NSRadii change: Rc(P) and Rs(P)Electron density changes ne(P)13Nanoshells under pressure
Vinet equation: J. Geophys. Res. 92, 9319 (1987)Vinet equation13Relative cross section:14Nanoshells under pressure
We calculate the peak shift:15Looking good!
SiO2HeNeH2The nanoshell is not in vacuum, but inside a pressure medium.16Pressure media
The shift changes directionAnd seems to stop for He and Ne17Not so good
18The coated nanoshell (CNS)
Add an extra layer:Will shield the influence of the mediumBut leaves the compressiblity
But how thick?AuSiO2
A thick layer is needed!19The coated nanoshell
1920Theoretical predictionsAverage resolution for CNS: 0,90 nm / GPa
Rubies: 0,36 nm/ GPa
Advantages:Nanoshells can be tuned to right frequency bandAre smaller and need less density
Disadvantage:Callibration is still needed21ExperimentsPage left blank intentionally22OutviewExperimental verificationFinetuning of theoryHeatingUse as biosensor
Sensing of metallic hydrogenNanoshells under pressureQuestions?23
21 July 2012
Published: N. Van den Broeck et al. JAP 110, 114318 (2011)24Extra: waarom geen vol SiO2 bolletje?
R1 = 60 nmR2 = 75 nmR3 = 200 nm
R = 200 nm25Extra: waarom geen Au kern en dikke SiO2 schil?
R1 = 60 nmR2 = 75 nmR3 = 200 nm
R1 = 75 nmR2 = 200 nm26Extra: waarom geen Au kern en dikke SiO2 schil?