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Near‐infrared surface‐enhanced Raman scattering can detect single molecules and observe ‘hot’ vibrational transitions
Author(s) -
Kneipp Katrin,
Kneipp Harald,
Manoharan Ramasamy,
Itzkan Irving,
Dasari Ramachandra R.,
Feld Michael S.
Publication year - 1998
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199808)29:8<743::aid-jrs294>3.0.co;2-m
Subject(s) - raman scattering , raman spectroscopy , excited state , molecule , coherent anti stokes raman spectroscopy , chemistry , infrared , spectroscopy , fluorescence , population , analytical chemistry (journal) , infrared spectroscopy , x ray raman scattering , molecular vibration , molecular physics , materials science , atomic physics , optics , physics , organic chemistry , demography , quantum mechanics , chromatography , sociology
Surface‐enhanced Raman scattering (SERS) at an extremely high enhancement level opens up interesting and new spectroscopic possibilities. The effect combines the sensitivity of fluorescence spectroscopy with the high structural information content of Raman spectroscopy, and can be used for single molecule detection and identification. This paper reports single molecule detection and identification of ‘non‐absorbing’ molecules in colloidal silver solutions using near‐infrared excited surface‐enhanced Stokes and anti‐Stokes Raman scattering. SERS enhancement factors of the order of 10 14 –10 15 or, in other words, effective Raman cross‐sections between 10 ‐16 and 10 ‐15 cm 2 /molecule result in a significant transfer of ground state population to the first excited vibrational state due to the strong Raman process. This allows the observation of v=1 to v=2 (‘hot’) vibrational transitions in SERS additionally to v=0 to v=1 transitions ‘normally’ probed in a Raman experiment. © 1998 John Wiley & Sons, Ltd.