Relationship between surface-enhanced Raman scattering and the dielectric properties of aggregated silver films

Abstract

By using an evaporated silver film that has a continuously varying thickness, we have demonstrated the dependence of surface-enhanced Raman scattering (SERS) on the dielectric properties of the film. These results support local field models that are based on metal-particle resonances for SERS.

Adaptive silver films for surface‐enhanced Raman spectroscopy of biomolecules

“…A variety of structures have been found to be appropriate for SERS, including roughened metal electrodes [1][2][3], aggregated films [15], metal islands of different morphology [14,15,[17][18][19][20], and semicontinuous films near the percolation threshold [37][38][39]. Among SERS-active substrates, vacuum-evaporated nanostructured metal films are well suited for SERS mechanism studies and have a high potential for applications [14][15][16][17][18][19][20]24,[39][40][41][42][43].…”

“…Among SERS-active substrates, vacuum-evaporated nanostructured metal films are well suited for SERS mechanism studies and have a high potential for applications [14][15][16][17][18][19][20]24,[39][40][41][42][43]. The effect on the metal film due to deposition rate, mass thickness, and thermal annealing were studied in detail previously [18,[40][41][42][43].…”

“…SERS has also been shown to be sensitive to molecular orientation and to the distance from the metal surface [13]. Thus, SERS is well-suited for biomolecule studies in which specificity and sensitivity to the conformational state and orientation of the molecule are very important.The SERS enhancement mechanism originates in part from the large local electromagnetic fields caused by resonant surface plasmons that can be optically excited at certain wavelengths for metal particles of different shapes or closely spaced groups of particles [14][15][16][17][18][19][20][21]. For aggregates of interacting particles, which are often structured as fractals, plasmon resonances can be excited in a very broad spectral range [22].…”

Sensing Proteins With Adaptive Metal Nanostructures

“…13 The SERS enhancement mechanism originates in part from the large local electromagnetic fields caused by resonant surface plasmons that can be optically excited at certain wavelengths for metal particles of different shapes or closely spaced groups of particles. [14][15][16][17][18][19][20][21] For aggregates of interacting particles, which are often structured as fractals, plasmon resonances can be excited in a very broad spectral range. 22 In addition to electromagnetic field enhancement, metal nanostructures and molecules can form charge-transfer complexes that provide further enhancement for SERS.…”

“…[23][24][25][26][27][28][29] The resulting overall enhancement depends critically on the particle or aggregate nanostructure morphology, 22,[30][31][32][33][34][35][36] and it can be as high as 10 5 to 10 9 for the area-averaged macroscopic signal and 10 10 to 10 15 within the local resonant nanostructures. A variety of structures have been found to be appropriate for SERS, including roughened metal electrodes, [1][2][3] aggregated films, 15 metal islands of different morphologies, 14,15,[17][18][19][20] and semicontinuous metal films near the percolation threshold. [37][38][39] Among SERS-active substrates, vacuumevaporated nanostructured metal films are well suited for SERS mechanism studies and have a high potential for applications.…”