Optically transparent nanometal composite membranes

Abstract

Small metal particles embedded in an optically transparent matrix result in a composite material which can be transparent in the infrared and into the visible (metals are usually optically opaque). The nanoparticles of the metal are produced by the “template” method, where the material is synthesized within the pores of a nanoporous membrane (see Figure). magnified image

Template-Synthesized Nanoscopic Gold Particles: Optical Spectra and the Effects of Particle Size and Shape

“…The membranes 3 prepared in that study had much smaller pores (co. 50 nm in diameter), and the resulting particles showed extinction maxima in the visible spectrum reminiscent of aqueous gold colloids of similar size. In that work, we demonstrated how the template synthesis approach allows for simple control of gold nanocylinder aspect ratio and that varying the particle aspect ratio gives rise to systematic shifts in the extinction max-imum [10]. We also showed that the observed effects of particle shape are qualitatively consistent with the predictions of MaxwellGarnett Theory (M-G), which is a simple treatment for composite materials that addresses particle shape and orientation but not size [111.…”

Optical properties of composite membranes containing arrays of nanoscopic gold cylinders

“…The alumina template membranes were prepared electrochemically from Al metal [9,10]. The details of the membrane syntheses will be given in [10].…”

“…The details of the membrane syntheses will be given in [10]. These membranes contain cylindrical pores of uniform diameter [8][9][10]. Membranes with pore diameters of 50 nm were prepared for these studies.…”

“…Our goal, since publishing this work [8] 'as been to push this optical transparency into the visible portion of the spectrum. In order to accomplish this objective we synthesized alumina template membranes [9,10] with much smaller pore diameters than the membranes used in our previous work. We also modified the electrochemical methods used to deposit the metal particles in these "nanoporous" alumina membranes [101.…”

Ultrafast studies of gold, nickel, and palladium nanorods

“…SPRs not only contribute to stronger molecularoptical interactions on roughened films, i.e., irregularly shaped surfaces, but they also play a role in the unique properties and enhanced absorption of molecules on regular metallic structures, such as meshes that exhibit extraordinary transmission due to traveling SPRs. [28][29][30][31][32] Other interesting effects in the optical properties of metal nanoparticles include their transparency 3,33,34 and enhanced optical absorption and fluorescence. [35][36][37] There has also been significant interest in the electron dynamics of nanomaterials.…”