Nanoprisms and method of making them

• US 7,135,054 B2
• Filed: 09/26/2002
• Issued: 11/14/2006
• Est. Priority Date: 09/26/2001
• Status: Active Grant

• Current Assignee: Northwestern University
• Original Assignee: Northwestern University
• Inventors: Cao, Yunwei, Mirkin, Chad A., Jin, Rongchao
• Primary Examiner(s): WYSZOMIERSKI, GEORGE P
• Application Number:
  US10/256,875
• Publication Number:
  US 20030136223A1
• Time in Patent Office: 1,510 Days
• Field of Search: 198/430, 752/55
• US Class Current: 75/255
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 1/0553 Complex form nanoparticles, e.g. prism, pyramid, octahedron
• CPC Class Codes: B22F 2202/11 Use of irradiation
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 9/24 starting from liquid metal compounds, e.g. solutions
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C22C 5/06 Alloys based on silver
• CPC Class Codes: Y10S 977/773 Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/81 Of specified metal or metal alloy composition

Abstract

The invention is a novel photo-induced method for converting large quantities of silver nanospheres into nanoprisms, the nanoprisms formed by this method and applications in which the nanoprisms are useful. Significantly, this light driven process results in a colloid with a unique set of optical properties that directly relate to the nanoprism shape of the particles. Theoretical calculations coupled with experimental observations allow for the assignment of the nanoprism plasmon bands and the first identification of two distinct quadrupole plasmon resonances for a nanoparticle. Finally, unlike the spherical particles from which they derive and which Rayleigh light scatter in the blue, these nanoprisms exhibit scattering in the red, permitting multicolor diagnostic labels based not only on nanoparticle composition and size but also on shape.

Claims

1. A silver nanoprism comprising a single silver crystal.

2. The nanoprism of claim 1, having an edge length of between about 10 nm and about 60 nm.

3. The nanoprism of claim 1, having a triangular shape with an atomically flat top and bottom.

4. The nanoprism of claim 1, having an in-plane dipole plasmon resonance of 770 nm.

5. The nanoprism of claim 1, having an out-of-plane dipole plasmon resonance of 410 nm.

6. The nanoprism of claim 1, having an in-plane quadrupole resonance of 470 nm.

7. The nanoprism of claim 1, having an out-of-plane quadrupole resonance of 340 nm.

8. The nanoprism of claim 1, wherein a tip of the prism is removed.

9. The nanoprism of claim 8, wherein the removed tip is about 12 nm in height.

10. The nanoprism of claim 1, exhibiting Rayleigh scattering in the red.

11. A nanoparticle label comprising a single silver crystal nanoprism.

12. The nanoparticle label of claim 11, wherein the nanoprism has a triangular shape with an atomically flat top and bottom.

13. The nanoparticle label of claim 11, wherein the nanoprism has an in-plane dipole plasmon resonance of 770 nm.

14. The nanoparticle label of claim 11, wherein the nanoprism has an out-of-plane dipole plasmon resonance of 410 nm.

15. The nanoparticle label of claim 11, wherein the nanoprism has an in-plane quadrupole resonance of 470 nm.

16. The nanoparticle label of claim 11, wherein the nanoprism has an out-of-plane quadrupole resonance of 340 nm.

17. The nanoparticle label of claim 11, wherein a tip of the nanoprism is removed.

18. The nanoparticle label of claim 17, wherein the removed tip is about 12 nm in height.

19. The nanoparticle label of claim 11, exhibiting Rayleigh scattering in the red.

20. A silver nanoprism having an in-plane quadrupole resonance of 470 nm and an out-of-plane quadrupole resonance of 340 nm.

21. The nanoprism of claim 20, having an atomically flat top and bottom and an edge length of between about 10 nm and about 60 nm.

22. A silver nanoprism displaying both in-plane quadrupole resonance and out-of-plane quadrupole resonance.