Remote-Excitation SERS

The SERS remote excitation is based on propagating SPP on single well-defined ciystal Au nanowire with quasi-spherical termini has 

we investigate the propagation property of SPP in a single Au nanowire with quasi-spherical termini. The SEM picture in 

The continuous evolution of nanotechnology in these years led to the production of QID structures in a variety of morphologies such as nanowires, nanotubes, nanobelts, nanorods, and etc. [68-70]. In particular, QID metal oxides are crystalline structures with weii-defined chemicai composition, surface terminations, free from disiocation and other extended defects, which are attracting an increasing interest for both fundamental and applied science [71-74]. The QID transition-metal oxide M0O3 belt is synthesized 

SERS at points 4 and 6 in Fig. 8.18a. The 632.8-nm radiation from the HeNe laser was used as an excitation source. The size of the laser spot was small than 1 um. We use the high confocallity mode to acquire the Raman signal and the acquisition range was less than 1 m. in the (a), the 10% of the laser intensity was used and the integration time was 10 s while in the [b] the 50% of the laser intensity was used and the integration time was 20 s. Reprinted from Ref. [74] with kind permission from Springer Science+Business Media. 

Theoretically the SPR peak can be tuned to 325 and 244 nm by controlling the size and gap distance of nanospheres, and SERS enhancement can reach on the order of 10 Cl l ] for single and 10 for dimer nanoparticles at 325 and 244 nm. So, 

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Figure 8.15 (a) Sketch of remote excitation SERS technique, (b] SEM image of Au nanowire, (c) Optical image of propagation of SPP on An nanowire, (d) Remote excitation SERS and local SERS spectra. Reprinted with permission from Ref. [48]. Copyright (2011) American Chemical Society. 

Experimentally, the microwave-assisted synthesis of sensitive silver substrate has been shown very good SERS activity. The synthesized nanocube with the directed calcium chloride coalescence method demonstrated a high catal3 ic activity for degradation reaction of eosin Y, using SERS spectrum. SERS-active substrates can be controlled and tuned to the optimal SERS intensity with pressure. Remote excitation SERS by propagating plasmonic dielectric... 

The diameter for the uncollimated laser beam was approximately 0.5 cm at the sample or 0.2 cm interrogation volume in the glass vial used. A laser power at sample of 500 mW (max) was used to excite the Remote Raman spectra in the sample. This resulted in a power density value of approximately 2.5 W/cm. In contrast, typical Micro Raman SERS experiments used power densities in the order of 20,000 W/cm to excite the Raman Shift spectra of samples contained in capillary tubes with an interrogation volume of 5x10 cm. This represents 8,000-fold increase in energy density for the microscope experiments than the telescope based Raman experiments. 

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