4 Plasmon Resonances At Au Cuu-Ag Case Study

4 Plasmon Resonances for PS@Au-Cu-Ag Composite Nanoshells

4.1 Introduction
As shown in recent studies, various methods have been developed to expand the application area of noble metal nanoparticles and to control the morphology and the behavior. Composite microspheres with noble metal nanoshells have great advantages in catalysis, optics, conductivity, chemical sensors, and so on [1–5]. Moreover, these hybrid materials can prevent noble metal nanoparticles from agglomerating without the use of a stabilizer and can be easily retrieved, owing to the relatively large size of the supports. In particular, silver, with its outstanding combination of properties, has continued to be of great interest in terms of its potential applications
4.2.5 Preparation PS@Au-Cu-Ag
Take 45 ml water with 0.5 PS@Au seed (Solve CuSO4.5H2O +Ag in 5 ml water ) add to them, after 5 min mix with them 1.5ml K-H and add H2O2, in different amount of Ag and PS for half hour, then washing 3 times using water . We measured the absorption by UV and the morphology using the transmission electron microscope ( TEM).
4.3 Table of Materials
Name Cemical Name Type Name of Compony
Copper(II) sulft pentahydrate CuSo4.5H2o AR Sinopharm Chemical Reagent Co.Ltd
Sodium hydroxide NaOH AR Sinopharm Chemical Reagent Co.Ltd
Potassium Sodium Tartrate Tertrahy drat C4H4O6KN4 .4H2O AR Sinopharm Chemical Reagent Co.Ltd
Silver Nitrate AgNO3 AR Sinopharm Chemical Reagent Co.Ltd
Trisodium Citrate dihydrate C6H5Na3O7.2H2O AR Sinopharm Chemical Reagent Co.Ltd
Hydrogen Peroxide H2O2 AR Sinopharm Chemical Reagent Co.Ltd
Sodium borohydride NaBH4 AR Sinopharm Chemical Reagent
To investigate the optical properties of the Au-Cu-Ag NPs doped in the PS matrix, the samples of PS/Ag composites were diluted with deionized water for measurement of the absorption spectrum. Figure (4,5,6) b shows the UV-Vis absorption spectra of the PS/ Au-Cu-Ag nanoshell fabricated using different concentration of the [Ag]. relatively silver concentrations, a broad peaks is observed at which was assigned to the localized surface plasma resonance (LSPR) of Ag NPs bound to the surface of PS. The position and width of the SPR peak are linked with the size, amount and shape of the metal particles, also connected with its own dielectric constant and that around it. With changing the anisotropy of particles, the peak would vary in the visible and near-infrared spectrum regions [27–29].

However, as the silver coverage increased from a low to a high level, the Ag NPs density and the contacting area between Ag NPs and PS supports would increase; so, the absorption spectra of PS/Ag composites are mainly blue -shifted. the results may be explained as follows. As the silver coverage increases to a high level, the PS/Au-Cu-Ag composites mainly show the collective absorption behavior of the composite.

SERS Properties of PS/Au- Cu- Ag nanoshell