The structural basis for giant enhancement enabling single-molecule Raman scattering.
نویسندگان
چکیده
We find that giant surface-enhanced Raman scattering for adsorbates on silver surfaces is present only on surfaces that exhibit self-similar fractal topology as inferred from atomic force microscopy. The fractal character results in localizing the energy of incident photons to volumes of a few nanometers on a side, millions of times smaller than the diffraction limit. Consistent with this finding, we have found an enhancement in spontaneous Raman cross section of >13 orders of magnitude for adsorbates on silver surfaces demonstrated to be fractal. The location of "hot spots" on the fractal surfaces is found to be hypersensitive to incident wavelength and polarization even though the observed Raman scattering is strictly linear in incident intensity. These observations are consistent with localization of the photon energy facilitated by the disordered nature of fractal organization through interference between the incident wave and scattered radiation from silver nanoparticle surface plasmons. We also present a surface preparation method that consistently produces fractal topologies that support single-molecule Raman scattering.
منابع مشابه
Giant Raman enhancement on nanoporous gold film by conjugating with nanoparticles for single-molecule detection
متن کامل
Exploring the chemical enhancement for surface-enhanced Raman scattering with Au bowtie nanoantennas.
Single metallic bowtie nanoantennas provide a controllable environment for surface-enhanced Raman scattering (SERS) of adsorbed molecules. Bowties have experimentally measured electromagnetic enhancements, enabling estimation of chemical enhancement for both the bulk and the few-molecule regime. Strong fluctuations of selected Raman lines imply that a small number of p-mercaptoaniline molecules...
متن کاملSurface Enhanced Raman Scattering of Crystal Violet with Low Concentrations Using Self-Assembled Silver and Gold-Silver Core-Shell Nanoparticles
The active substrates in surface enhanced Raman scattering (SERS) spectroscopy were prepared through self-assembly of nanoparticles on functionalized glasses. Colloidal silver nanoparticles (Ag NPs) were prepared chemically in two different sizes by reduction of AgNO3 using trisodium citrate and sodium borohydride. Gold–silver core–shell nanoparticles were also prepared to compare between the o...
متن کاملStructural Analysis of Hirudin Using FT-IR and FT-Raman Spectroscopic Techniques
FT-IR and FT-Raman spectra of hirudin have been recorded from the native solid hirudin. The conformation of the molecule has been discussed on the basis of IR and Raman data. It has been concluded that hirudin molecule has a mixed a-helix and random coil conformation.
متن کاملSTRUCTURAL ANALYSIS OF CYCLOSPORIN-A BY RAMAN TECHNIQUE
The Raman spectrum of cyclosporin-A has been recorded in the solid phase. The conformation of the molecule has been discussed on the basis of Raman data. It has been concluded that in agreement with X-ray data, cyclosporin-A molecule has an antiparallel P- pleated sheet conformation. It may have some reverse P- turn structure in what has been assigned to a random coil conformation.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 100 15 شماره
صفحات -
تاریخ انتشار 2003