Surface enhanced Raman spectroscopy (SERS) substrates exhibiting uniform high enhancement and stability

• US 7,450,227 B2
• Filed: 09/20/2005
• Issued: 11/11/2008
• Est. Priority Date: 09/22/2004
• Status: Expired due to Fees

• Current Assignee: Penn State Research Foundation
• Original Assignee: Penn State Research Foundation
• Inventors: Allara, David L., Dwight, David W.
• Primary Examiner(s): Toatley, Jr.; Gregory J.
• Assistant Examiner(s): Underwood; Jarreas C
• Application Number:
  US11/231,177
• Publication Number:
  US 20060061762A1
• Time in Patent Office: 1,148 Days
• Field of Search: 356/301, 359/327, 359/334, 372/3
• US Class Current: 356/301
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G01N 21/658 enhancement Raman, e.g. surface plasmons

Abstract

An improved substrate for Raman spectroscopy of an analyte comprises a porous metal film. Enhancement factors and uniformity of the substrate can be enhanced by electrochemical roughening of the film. Improved sensors and spectrometers using such substrates are also described.

Claims

1. A method of preparing a substrate for surface enhanced Raman spectroscopy, the method comprising:

preparing an alloy film, the alloy film including a first metal and a second metal; and

removing most of the second metal, so as to obtain a porous film of the first metal, the porous film of the first metal being the substrate for surface enhanced Raman spectroscopy.

2. The method of claim 1, wherein removing most of the second metal comprises acid etching of the alloy film, the acid dissolving the second metal.

3. The method of claim 1, wherein preparing the alloy film comprises sputter deposition of the alloy film.

4. The method of claim 1, wherein the first metal is gold.

5. The method of claim 4, wherein the second metal is silver.

6. The method of claim 1, wherein the alloy film has a film thickness, the film thickness being less than approximately 500 nm.

7. The method of claim 5, wherein the film thickness is between approximately 150 nm and approximately 500 nm.

8. The method of claim 1, wherein removing most of the second metal comprises acid etching of the second metal from the alloy film.

9. The method of claim 1, further comprising electrochemical roughening of the porous film of the first metal.

10. A substrate useful for surface enhanced Raman spectroscopy (SERS), the substrate comprising a porous metal film,

the porous metal film having a film thickness between approximately 150 nm and approximately 500 nm, and

the substrate having a SERS enhancement factor of at least 10⁷.

11. The substrate of claim 10, wherein the porous metal film has a columnar structure.

12. The substrate of claim 10, wherein the porous metal film includes a metal selected from a group of metals consisting of gold, silver, and platinum.

13. An apparatus for detecting an analyte, comprising:

a substrate;

a radiation source, the radiation source operable to provide incident radiation on the substrate; and

a detector, the detector positioned to receive scattered radiation from the analyte when the analyte is adsorbed on the substrate, the scattered radiation being used to detect the analyte,

wherein the substrate comprises the porous metal film of claim 10,

the porous metal film including a metal selected from a group of metals consisting of gold, platinum, and silver.

14. The apparatus of claim 13, wherein the incident radiation has a wavelength that excites surface plasmons within the substrate.

15. The apparatus of claim 13, wherein the substrate is a porous gold film.

16. The apparatus of claim 13, wherein the substrate is an electrochemically roughened porous gold film.

17. The apparatus of claim 13, wherein the porous metal film has a film thickness between approximately 150 nm and approximately 500 nm.

18. The apparatus of claim 13, the apparatus further operable to clean the substrate so as to remove the analyte from the substrate.

19. The apparatus of claim 13, wherein the apparatus is a Raman spectrometer, and the radiation source is a laser.

20. The apparatus of claim 13, wherein the substrate is supported on a rotating carousel, the rotating carousel supporting a plurality of substrates.