The blueshifting of the ZnO absorption may be in principle understood in the quantum confinement due to the reduced particle dimension and the solvent effects [10], as described by the expression Figure 4 UV-visible

absorbance spectra of the polymer-laced ZnO-Au hybrid nanoparticles dispersed in different solvents. Hexane (a), water (b), and ethanol (c), in Selleck Thiazovivin comparison to Au (d) and ZnO (e) nanoparticles (both in hexane). where and ϵ = ϵ 2/ϵ 1. In the expression, E g(R) and E g(bulk) represent the bandgap energies of the nanoparticles of radius R and the bulk material with a dielectric constant ϵ 2 surrounded in a medium of dielectric constant ϵ 1. The parameters m e and m h indicate the effective masses of the electron and the hole of the exciton, whereas e is the electron charge and ħ the Planck constant divided by RG7112 ic50 2π. The bracket <> means average over a wave function of position r. In addition to the change observed in the band positions from the ZnO nanoparticles to the Au-ZnO see more nanoparticles, comparing the shapes of the bandgap absorption in Figure 4a,e further sheds light on the impact of Au on ZnO, in which the Au-ZnO nanoparticles show increased absorption intensity with the decreasing wavelength against the almost flat absorption of the ZnO nanoparticles. As revealed in

the multiple domain nanostructure from the TEM analysis above, moreover, the Au nanocrystallites in the hybrid nanoparticles produce more surface and interface defects, i.e., imperfect lattices and oxygen vacancies that are expected to generate a defect level in the energy band, Methane monooxygenase resulting in likely contributions of more induced excitons and increased exciton density to the moderate enhancement in the absorption intensity in the UV range. Furthermore, the SPR action induced by the Au nanocrystallites, which is to be addressed below, offers additional channels to absorb the

incident electromagnetic waves and thus probably augment the UV absorption of the hybrid nanoparticles. The second well-defined absorption between 520 and 550 nm features the optical property of surface plasmon resonance in consequence of Au nanostructuring [27, 28, 33, 34]. Dependent on the solvent, the peak position of the plasmon band in the solution of the Au-ZnO nanoparticles varies from approximately 533 nm in hexane, approximately 550 nm in water, to approximately 542 nm in ethanol, in comparison to the Au nanoparticles in hexane which has an absorption peaking at approximately 525 nm. Nominally, the peak position and band shape of the plasmon resonance may be subject to factors of composition, dimension, nanostructure shape, dielectric medium, and nanostructuring of the nanoparticle system [33–35].