Abstract
In this paper, large-area magnetic–plasmonic Ni@Au core–shell nanoparticle arrays (NPAs) with tunable compositions were successfully fabricated by a direct laser interference ablation (DLIA) incorporated with thermal dewetting method. The magnetic properties of the Ni@Au core–shell NPAs were analyzed and the saturation magnetization (Ms) of the Ni80@Au20 nanoparticles was found to be higher than that of nickel-only nanoparticles with the same diameter. Using Rhodamine 6G (R6G) as a Raman reporter molecule, the surface enhanced Raman scattering (SERS) property of the Ni@Au core–shell NPAs with a grain size distribution of 48 ± 42 nm and a short-distance order of about 200 nm was examined. A SERS enhancement factor of 2.5 × 106 was realized on the Ni50@Au50 NPA substrate, which was 9 times higher than that for Au nanoparticles with the same size distribution. This was due to the enhanced local surface plasmon resonance (LSPR) between the ferromagnetic Ni cores and the surface polariton of the Au shells of each nanoparticle. The fabrication of the Ni@Au core–shell NPAs with different compositions offers a new avenue to tailor the optical and magnetic properties of the nanostructured films for chemical and diagnostic applications.
Highlights
IntroductionGold nanoparticles exhibit fascinating bio-compatibility and optical properties owing to their strong localized surface plasmon resonance (LSPR), and are incredibly useful in a wide range of chemical and biological applications, such as biomedicine,[1,2,3] biological optical imaging,[4] sensing,[5] energy,[6] catalysis[7] and surface enhanced Raman scattering (SERS).[8]
A nanosecond laser (Innolas) three-beam interference ablation system with a wavelength of 1064 nm, a frequency of 10 Hz and a pulse duration of 7 ns was employed for the direct laser interference ablation (DLIA)
The fabrication of large-area, cost-effective nanoparticle arrays (NPAs) substrates with tunable composition of Ni@Au core–shell nanostructures was presented in the paper
Summary
Gold nanoparticles exhibit fascinating bio-compatibility and optical properties owing to their strong localized surface plasmon resonance (LSPR), and are incredibly useful in a wide range of chemical and biological applications, such as biomedicine,[1,2,3] biological optical imaging,[4] sensing,[5] energy,[6] catalysis[7] and surface enhanced Raman scattering (SERS).[8] Among these applications, large-area Au nanoparticle arrays (NPAs) are good SERS substrates as an attractive tool for measuring a small number of molecules with high sensitivity.[9,10,11,12,13] The resonant interactions of the Au nanoparticles with incident electromagnetic radiation facilitate enhanced Raman scattering. SERS measurement results of R6G on the as-prepared Ni@Au core–shell NPA substrates were compared to observe the dependence of SERS intensity on the metal compositions
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