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Key Factors Influencing SERS

SERS activity, which mainly arises from localized surface plasmon resonance, depends critically on the optical properties, size, shape, and inter-particle space of nanostructures. [Pg.119]

Besides the coinage metals, alkali metals (Li, Na, K, Rb, Cs) and A1 can also function as plasmonic materials, though it is very difficult to prepare stable nanostructured surfaces composed of these chemically active materials. Aluminum is a typical plasmonic material in the UV regime [39-41], while Ga, In, Pt and Rh, as well as their alloys and some complex materials (e.g., TiN), have also been explored as plasmonic materials [42]. [Pg.119]

According to Van Duyne et al. [43,44], in order to obtain SER spectra with enhancement factors as large as possible, the excitation and scattering wavelengths should, if possible, sit at the two sides of a surface plasmon resonance extinction peak [43,44]. In addition, the excitation wavelength can be selected corresponding to the molecular absorption, and [Pg.119]

SERS is an interface-sensitive technique, with molecules adsorbed in the first layer at the surface showing the largest enhancements. However, electromagnetic enhancement has a long-range property (i.e., it decays exponentially with increasing distance from the surface, 1-10 nm) [45-48], which predicts that SERS does not require the adsorbate to be in direct contact with the surface but rather within a certain sensing volume. [Pg.120]

The localized surface plasmon resonance of individual plasmonic nanoparticles depends heavily on the size and shape of each nanoparticle. For instance, the wavelength of the dipolar surface plasmon red shifts with the increase of particle size. However, for much larger nanoparticles new bands for some multipolar modes will appear in the short-wavelength range, while the dipolar band at long-wavelength will be damped. Typically, the size of Au or Ag nanoparticles synthesized for SERS should be less than 150 nm, and larger than 20 nm. [Pg.121]


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