Ion irradiation synthesis of Ag–Au bimetallic nanospheroids in SiO2 glass substrate with tunable surface plasmon resonance frequency

Abstract

Ag-Au bimetallic nanospheroids with tunable localized surface plasmon resonance (LSPR) were synthesized by 100 keV Ar-ion irradiation of 30 nm Ag-Au bimetallic films deposited on SiO 2 glass substrates. A shift of the LSPR peaks toward shorter wavelengths was observed up to an irradiation fluence of 1.0 Â 10 17 cm À2, and then shifted toward the longer wavelength because of the increase of fragment volume under ion irradiation. Further control of LSPR frequency over a wider range was realized by modifying the chemical components. The resulting LSPR frequencies lie between that of the pure components, and an approximate linear shift of the LSPR toward the longer wavelength with the Au concentration was achieved, which is in good agreement with the theoretical calculations based on Gans theory. In addition, the surface morphology and compositions were examined with a scanning electron microscope equipped with an energy dispersive spectrometer, and microstructural characterizations were performed using a transmission electron microscope. The formation of isolated photosensitive Ag-Au nanospheroids with a FCC structure partially embedded in the SiO 2 substrate was confirmed, which has a potential application in solid-state devices. V C 2013 AIP Publishing LLC. [http://dx

Effects of ion and nanosecond-pulsed laser co-irradiation on the surface nanostructure of Au thin films on SiO2 glass substrates

“…As a result, the Au thin films take on the properties of the liquid state, and dewetting of the films occurs. 14,15,[17][18][19][20][21][22][23] At the beginning of dewetting, holes grow on the surface of the thin film, and continues to expand. Generally, grain boundaries play an important role in hole formation.…”

“…Recently, we synthesized noble metal nanoparticles with a narrow size distribution embedded in SiO 2 glass substrates 21,23 and Al 2 O 3 single-crystal substrates 22 via Ar þ ion irradiation. We also synthesized Au nanoparticles that formed periodic arrays on SiO 2 glass substrates through nanosecond-pulsed laser irradiation.…”

“…By tuning the LSPR frequency using these factors, metallic nanoparticle/dielectric systems can be devised for applications such as biosensors, [5][6][7][8][9][10][11] plasmonic waveguides, 12 and photocatalysts. 13 Metallic nanostructures can be prepared on the surface of metallic thin films deposited on dielectric or semiconductor substrates via irradiation of the surface with a quantum beam such as an ion beam, [14][15][16][17][18][19][20][21][22][23] nanosecond-pulsed laser, 24,25 or electron beam. 26 Surface nanostructures are formed by dewetting caused by irradiation with a quantum beam.…”

“…We anticipate that co-irradiation will accelerate the formation of periodic structures because of our previous results showing that the LSPR frequency depended on the morphology (size, embedded depth, and interparticle distance) of the formed nanostructures. [21][22][23]31 Microstructural analyses of the samples are performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical absorbance of the samples is also measured, with emphasis on the correlation between their optical properties and nanostructures.…”

“…26 Surface nanostructures are formed by dewetting caused by irradiation with a quantum beam. [14][15][16][17][18][19][20][21][22][23][24][25][26] Under ion irradiation, metal nanoparticles that form on the surface through the dewetting process become embedded in SiO 2 glass 21,23 and Al 2 O 3 22 substrates because the viscosity of the substrate changes and it undergoes plastic flow during ion irradiation. 16,19 Laser-induced periodic surface structures (LIPSS) can be obtained via nanosecond-pulsed laser irradiation.…”