Surface Enhanced Raman Scattering (SERS) Effect and Applications

Cheng Guo07/15/2008

Mini Symposium on Surface Plasmons

1. Introduction to Surface enhanced Raman scattering (SERS)

1920’s discovery of

Raman effect

1970’s discovery of SERS effect of pyridine on silver electrode surfaces

J. Am. Chem. Soc. 1977,99,5215

2. Theoretical explanations for SERS

A. Electromagnetic field enhancement mechanismexcitation of surface plasmontends to form spacially localized “hot areas”the magnitude of enhancement ~106- 107 times for single colloidal silver, and ~108 for the gap between two coupled particles

B. Chemical enhancement due to specific interactions, forming charge-transfer complexesthe magnitude of chemical enhancement ~10-100 times

    3. SERS applications

Efficient enhancing substrates: Ag, Au and Cu, rough surfaces or colloidal particles with the size of tens of nanometers

classical electrochemical studiese.g. corrosion processes, film growth, self-assembled monolayers

surface enhanced anti-stokes Raman scatteringsurface enhanced resonance Raman scattering (SERRS)

biological samplese.g. DNA/protein detection

trace analysis approaching single molecule detection limite.g. 100 pyridine molecules on Ag electrode

4. SERS related to our research

Vibrational spectroscopy, 2007, 43, 415

Example 1: C60 SERS signals

How about use H2@C60 in this system?

(a)

(b)

(c)

Example 2: multiplex SERS signals for DNA detection

Science 2002, 297, 1536

PNAS, 2008, 105, 9145

Multiplex SERS application: four-color DNA sequencing by synthesis

J.Phys.Chem. B, 2002, Vol. 106, 311

Example 3: SERS single nanoparticle imaging

Detection of azido-dNTP for DNA sequencing

N=N=N asymmetric stretching at 2088

cm-1

Biospectroscopy1998, 2, 233

Summary

1. Surface Enhanced Raman Scattering (SERS) has been discovered for many decades and the surface plasmon resonance theory helped explain the mechanism

2. SERS was applied in many research fields. Current study of SERS in C60, multiplex SERS for DNA detection and AZT-dNTP SERS signals are useful to our research