It was previously found that by controlling the initial size of t

It was previously found that by controlling the initial size of the gold sulfide particles, the resonance shift can be correlated with a theoretical model that includes both quantum confinement and the resonance effects (the so-called surface plasmon resonance) [22]. Ultra-smooth

surfaces from template-stripping procedures can be also used for periodic structures preparation [23], which can induce effects of surface plasmon resonance. The behavior of annealed gold nanolayers prepared by evaporation is rather different. The peak of plasmon resonance can be found for the annealed samples of thicknesses up to 7 nm (see Figure 5). In addition, the shift of the peak of plasmon resonance towards higher wavelengths as described earlier [5] was observed. PD0332991 concentration The suppressed diffusion of the evaporated gold nanolayers during the annealing process may be the leading cause in the plasmon peak appearance. Figure 5 UV–vis LDN-193189 datasheet spectra of gold structures evaporated on glass

– before (RT) and after annealing (annealing). The numbers of the curves are Au thicknesses in nanometers. The difference in absorbancies in extinction spectra of evaporated structures under RT and evaporated onto substrate heated to 300°C can be determined from Figure 6. The surface plasmon peak has been observed for the layer thickness up to 10 nm. The absolute value of the absorbance is higher in comparison to annealed structures, Ilomastat price which is probably caused by the changes in structure morphology, density

and size of Au clusters on the examined surface. The shift of the plasmon peak for lower thickness of Au was observed. This is probably caused by the interaction of gold nanoparticles, which may arise from a different mechanism of gold nanostructure growth when compared to the annealed one and when the layer is deposited on non-heated substrate. Figure 6 UV–vis spectra of gold structures evaporated on glass heated to 300°C (300°C). The numbers of the curves are Au thicknesses in nanometers. Surface plasmon resonance (SPR) can be described Vitamin B12 as a collective oscillation of electrons in solid or liquid stimulated by incident light. The condition for the resonance appearance is established when the frequency of light photons matches the frequency of surface electrons oscillating against the restoring force of the positive nuclei. This effect when occurring in nanometer-sized structures is called localized surface plasmon resonance. Surface plasmons have been used to enhance the surface sensitivity of several spectroscopic measurements including fluorescence, Raman scattering, and second harmonic generation. Also, SPR reflectivity measurements can be used to detect molecular adsorption, such as polymers, DNA or proteins, and molecular interaction studies [24]. The shift of the curves in extinction spectra can be explained by the coupling of the electromagnetic field between surface plasmons excited in gold nanoparticles of different densities and sizes.

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