Nanoantenna scanning probe tip, and fabrication methods
View Patent ↗The invention provides a nanoantenna scanning probe tip for microscropy or spectroscopy. The nanoantenna scanning probe tip includes a sharp probe tip covered with a contiguous film of predetermined sized and shaped plasmonic nanoparticles. A method for forming the nanoantenna scanning probe tip by trapping nanoparticles having a predetermined size and shape at a liquid surface using surface tension, forming a uniform and organized monolayer film on the liquid surface, and then transferring portions of the film to a sharp probe tip. In preferred embodiments, the sharp probe tip is one of a conductive STM (scanning tunneling microscopy) tip, a tuning fork tip or an AFM (atomic force microscopy) tip. The sharp tip can be blunted with an oxide layer.
1. A method for fabricating a nanoantenna scanning probe, comprising:
placing a sharp probe tip in liquid under a liquid surface;
trapping nanoparticles having a predetermined size and shape on the liquid surface using surface tension;
forming a uniform and organized monolayer film on the liquid surface; and
transferring portions of the organized monolayer film to the sharp probe tip to coat the sharp probe tip with a monolayer of the nanoparticles by moving the sharp prove tip through the organized monolayer film on the liquid surface.
2. The method of claim 1 , wherein the sharp probe tip comprises a conductive STM (scanning tunneling microscopy) tip.
3. The method of claim 1 , wherein the sharp probe tip comprises a tuning fork tip.
4. The method of claim 1 , wherein the sharp probe tip comprises an AFM (atomic force microscopy) tip.
5. The method of claim 1 , wherein the sharp probe tip comprises a blunted tip.
6. The method of claim 5 , wherein the sharp probe tip blunted with an oxide or nitride layer.
7. The method of claim 6 , wherein sharp probe tip comprises a blunted AFM tip.
8. The method of claim 6 , comprising a step of plasma enhanced chemical vapor deposition to form the oxide layer.
9. The method of claim 8 , wherein the oxide blunts the tip to a radius of curvature such that the size of the nanoparticles to the radius of curvature is ˜1:1.
10. The method of claim 1 , comprising transferring portions of the film to a plurality of sharp probe tips.
11. The method of claim 1 , wherein the nanoparticles comprise silver nanocubes.
12. The method of claim 1 , wherein the nanoparticles comprise gold bipyramidal nanoparticles.
13. The method of claim 1 , wherein the AFM tip comprises silicon blunted with a silicon dioxide coating.
14. The method of claim 1 , wherein said forming comprises compressing the nanoparticle film.
15. The method of claim 14 , wherein said transferring comprises bringing the sharp probe tip into contact with the nanoparticle film via a mechanical mover.
16. The method of claim 14 , wherein the mechanical mover brings the apex of the sharp probe tip first into contact with the nanoparticle film.
17. A nanoantenna scanning probe tip for microscropy or spectroscopy comprising sharp probe tip covered with a contiguous monolayer film of predetermined sized and shaped plasmonic nano particles, wherein the sharp prove tip comprises a blunted AFM tip, conductive STM tip or tuning fork tip, having a radius of curvature that equals or exceeds a seize of the plasmonic nano particles.
18. The nanoantenna scanning probe tip of claim 17 , wherein the AFM tip is blunted with an oxide or nitride coating.
19. The nanoantenna scanning probe tip of claim 17 , further comprising a protective coating over the plasmonic nano particles.
20. The nanoantenna scanning probe tip of claim 17 , wherein the nanoparticles comprise silver nanocubes.
21. The nanoantenna scanning probe tip of claim 17 , wherein the nanoparticles comprise gold bipyramidal nanoparticles.
22. The nanoantenna scanning probe tip, of claim 17 , wherein the sharp probe tip comprises a silicon AFM (atomic force microscopy) tip blunted with a silicon dioxide coating.
23. The nanoantenna scanning probe tip of claim 17 , wherein the sharp probe tip comprises a conductive STM (scanning tunneling microscopy) tip.
24. The nanoantenna scanning probe tip of claim 17 , wherein the sharp probe tip comprises a tuning fork tip.
25. A method for scanning probe spectroscopy, the method comprising:
bringing a nanoantenna scanning probe into contact or near a surface, wherein the nanoantenna scanning probe comprises a sharp probe tip coated with a monolayer film of plasmonic nanoparticles, wherein the sharp probe tip comprises a blunted AFM tip, conductive STM tip or tuning fork tip, having a radius of curvature that equals or exceeds a size of the plasmonic nano particles;
moving the probe relative to the surface;
directing a radiation beam at the probe during said moving; and
obtaining spectra from the probe during said moving.
26. The method of claim 25 , wherein the nanoparticles comprise silver nanocubes.
27. The method of claim 25 , wherein the nanoparticles comprise gold bipyramidal nanoparticles.
28. The method of claim 25 , wherein the radiation beam comprises a 488-1064 nm laser beam.
29. The method of claim 28 , wherein the radiation beam comprises a ˜700 nm to ˜850 nm nm laser beam.