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Quantitative measurements of non contact interaction

Quantitative measurements of non contact interaction. G. Torricelli , M. Rodrigues, C. Alandi, M.Stark, F. Comin J. Chevrier Université Joseph Fourier Grenoble LEPES CNRS Grenoble Spectro CNRS UJF ESRF Grenoble. Coll. S. Huant, F. Martins Spectro

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Quantitative measurements of non contact interaction

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  1. Quantitative measurements of non contact interaction G. Torricelli, M. Rodrigues, C. Alandi, M.Stark, F. Comin J. Chevrier Université Joseph Fourier Grenoble LEPES CNRS Grenoble Spectro CNRS UJF ESRF Grenoble Coll. S. Huant, F. Martins Spectro Coll. G. Jourdan, A Lambrecht, S Reynaud LKB

  2. …. forces are acting at the Nanoscale on MEMS and on NEMS <<1mm Courtesy of Hubert GRANGE and Marie-Thérèse DELAYE (2004) CEA LETI

  3. Nature of forces at Nanoscale: Photonic Radiation pressure van der Waals interaction Casimir effect Electrostatic Brownian Motion (kBT) Hard core repulsion Adhesion-metallic bonding Dissipation MEMS Parameters: atmosphere-vacuum surface roughness chemical nature nanostructuration restoring force (mechanical spring constant) surface/bulk elastic stress

  4. When micromechanics and quantum electrodynamics meet: MEMS based on Casimir-Lifschitz forces Federico Capasso FCas= 3pN L=1000nm=1mm A=50mmx50mm Strong gradient: FL5 > K mechanical instability

  5. tip R Z surface Radius of interaction R= 50mm no longer local no microscopy

  6. Origin: electron-photon coupling Characteristic length: plasma length l p  100nm l p= 2p c/ w p Aluminum ћw p= 14eV • L >> l p retarded régime (Casimir régime) • electron coupling to propagating photon modes dominant • L << l pNON retarded régime (Van der Waals) • electron coupling to NON propagating photon modes dominant: • surface plasmon-photon coupling

  7. Large distance limit and perfect mirror Casimir limit L>>l p Radiation pressure of virtual photons i.e. zero point motion of ElectroMagnetic field L=100nm (retarded régime L />l p ) F=100 picoN F =10-3 N/m

  8. L=10nm (non retarded van der Waals régime L<< l p ) F= H R/ L2 H=5x 10-19 Joule F=500 nanoNewton F =50N/m +++ --- +++ --- +++ --- E E z x Hy e e metal ( metal ( <0) <0) +++ --- +++ --- +++ --- 1 2 d J.J. Greffet EM2C Ecole Centrale de Paris 2003

  9. Measure (G. Torricelli PhD thesis LEPES 2001-2004)Omicron VT UHV AFM V 100nm < z < 500nm polystyrene sphere R= 42 mm metal coating (gold) =300 nm

  10. Static cantilever deflection F= -kx Sphere/surface distance determination Cantilever spring constant measurement

  11. Cantilever deflection cannot be neglected at large voltage Dzdef z

  12. V wres wres F Vdw/ Casimir: Oscillating mode of the sphere at resonance

  13. fres=52.670 kHz K ≈ 88.6N/m 86.4 mm Casimir/vdw interaction (fit in z-3) Z ≈ 0.05 - 0.4 mm lp≈ 130nm Electrostatic long range interaction DV=0.5volt (fit in z-2) L=50nm grad F= 10-1 N/m

  14. Short distances: D<<lp with lp plasmon length, Tuning fork K= 1000 - 10000 N/m Force machine: sphere-surface distance 10nm

  15. Full scale is 0.3Hz The distance is again determined using capacitive interaction

  16. Large surface roughness at the origin of our measurement no van der Waals contribution, instead direct metallic bonding

  17. At nanoscale, attractive force between 2 metallic plates in vacuum

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