Near-infrared surface-enhanced Raman scattering can detect single molecules and observe ‘hot’ vibrational transitions
✍ Scribed by Katrin Kneipp; Harald Kneipp; Ramasamy Manoharan; Irving Itzkan; Ramachandra R. Dasari; Michael S. Feld
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 238 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0377-0486
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✦ Synopsis
Surface-enhanced Raman scattering (SERS) at an extremely high enhancement level opens up interesting and new spectroscopic possibilities. The e †ect combines the sensitivity of Ñuorescence spectroscopy with the high structural information content of Raman spectroscopy, and can be used for single molecule detection and identiÐcation. This paper reports single molecule detection and identiÐcation of "non-absorbingÏ molecules in colloidal silver solutions using near-infrared excited surface-enhanced Stokes and anti-Stokes Raman scattering. SERS enhancement factors of the order of 1014-1015 or, in other words, e †ective Raman cross-sections between 10-16 and 10-15 cm2/molecule result in a signiÐcant transfer of ground state population to the Ðrst excited vibrational state due to the strong Raman process. This allows the observation of v = 1 to v = 2 ("hotÏ) vibrational transitions in SERS additionally to v = 0 to v = 1 transitions "normallyÏ probed in a Raman experiment.