Nanoporous gold—Application to extraordinary optical transmission of light

Abstract

The authors present their work in the preparation of nanoporous gold layers and their patterning with an original procedure preserving the porosity, to obtain the phenomenon of extraordinary transmission of light with a porous material. The design, fabrication, and characterization of nanoslit arrays made with bulk gold and nanoporous gold films are presented and their sensing performances are compared after coating with thiolated organic molecules. Thanks to a greatly enhanced surface-to-volume ratio, nanoporous gold reveals benefits for better reaction efficiency and detection sensitivity. Moreover, plasmonic properties in the near-IR range assure employment in plasmonic devices.

Engineered/tailored nanoporous gold structures for infrared plasmonics

“…The simulated nanorods were fabricated by means of FIB lithography following a procedure that allows to preserve the 3D porosity of the materials [4]. Figure 6 reports an example of such fabricated nanorods.…”

“…In order to maintain the porous structure after lithography, the approach previously reported was used [4]: an additional Ag layer (ca.120 nm) was evaporated over the NPG film; the bilayer structure was then milled by means of FIB with a single exposure, realizing rod arrays over an area 30x30 μm; the Ag layer serves as a protective layer providing more efficient heat dispersion during milling and thereby preventing the melting of the gold porous structure and was easily removed in HNO 3 (at 20 °C) after the exposure. The sample was then rinsed and dried.…”

“…With regard to this phenomenon we demonstrated that a nanoporous gold (NPG) substrate can improve the sensitivity of a surface plasmon resonance (SPR) based biosensor, taking advantage of the high surface to volume ratio of the material. The experimental verification was performed on a digital grating by measuring the SPR shift in reflectance and transmittance in the visible range [2][3][4][5]. The research efforts are still focused on the quest for novel plasmonic materials.…”

Development of a complete plasmonic grating-based sensor and its application for self-assembled monolayer detection

“…We have chosen a gold digital grating as the plasmonic structure thanks to its ability to support different resonances [18,[27][28][29]. High-quality gratings have been produced using a nanofabrication process based on the electron beam lithography.…”

Tuning Localized Surface Plasmon Resonance of Nanoporous Gold with a Silica Shell for Surface Enhanced Raman Scattering

“…Numerous nanoporous metals (NPM) that were obtained via dealloying exhibit a bicontinuous network and have been demonstrated to possess superior optical properties [ 1 , 2 , 3 , 4 ]. Among these, nanoporous gold (NPG) has stood apart for use in analytical and sensing applications, such as surface enhanced Raman scattering (SERS) [ 5 , 6 , 7 ], surface enhanced fluorescence (SEF) [ 8 , 9 , 10 ], and bio-chemo-sensing [ 1 , 11 , 12 ].…”