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Abstract Experimental technique for preparing of space arranged arrays of bimetallic AuAg nanoparticles in the near-surface region of glass, exhibiting surface plasmon resonance (SPR) characteristics varying in the wider ranges comparing to monometallic Au, Ag particles or corresponding thin films, is presented together with the structural characterization of the obtained particles. The suggested technique is based on the UV laser irradiation (λ = 193 nm) of the glass surface preliminary doped with silver ions and then sputter coated by a thin gold layer. Optical extinction spectra of the prepared AuAg/glass samples demonstrated strong dependence of SPR upon the number of laser pulses applied. The relationship "SPR characteristics – particles structure and composition – synthesis conditions" was studied using transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence (XRF) method and X-ray absorption fine structure (XAFS) spectroscopy. The latter provided the structural information on Au Ag bonds, which directly evidenced on the formation of bimetallic AuAg nanoparticles in AuAg/glass samples. The XAFS derived values of structural parameters of Au Au and Au Ag bonds allowed to visualize the distribution of gold and silver over the volume of representative AuAg nanoparticle and to suggest the most plausible cluster models of the architecture of such particle for the prepared AuAg/glass samples. It was revealed that the core-shell architecture of Au@Ag particles (Au-core, Ag-shell) is the most plausible in AuAg/glass samples prepared by the low number of laser pulses, while the structure of disordered solid solution is suitable for AuAg particles in samples prepared by ∼ 50 and more pulses. Calculations of contributions into experimental optical extinction spectra of AuAg/glass samples from particles with the revealed composition, size and architecture were performed to prove that the proposed structural models of nanoparticles are not in contradiction with the observed optical properties of the samples. Graphical abstract Image 1 Highlights • UV laser irradiation of preliminary prepared glasses forms plasmonic AuAg NPs arrays. • SPR of AuAg/glass samples shows strong dependence upon the number of laser pulses. • Most plausible architecture of AuAg NPs at low number of pulses is Au-core@Ag-shell. • AuAg NPs prepared by ∼50 and more pulses have the structure of solid solution. • Structural models of NPs are supported by calculations of optical extinction spectra. [ABSTRACT FROM AUTHOR]

To develop a technique for the production of submicron line patterns and directed arrays of plasmonic nanoparticles, the generation and implantation of gold nanoparticles into float glass surfaces was studied by means of ArF-excimer laser irradiation (193 nm) below the ablation threshold of the glass which was sputter coated with a gold layer with a thickness of 70 nm. The formation of gold particles was confirmed by the characteristic surface plasmon resonance (SPR) peak at ∼550 nm. The intensity of the SPR peak of gold particles embedded in the glass matrix increases with the number of applied laser pulses, indicating a different degree of implantation of the gold nanoparticles into the glass surface. It was revealed that the laser implantation of the generated gold particles into the glass is supported on the tin-bath side by the enhanced absorption of tin ions. The dependences of SPR parameters upon the number of laser pulses at different fluences were obtained. Using the methods of X-ray diffraction and extended X-ray absorption fine structure, the mean size of implanted gold particles was estimated at 15–20 nm. This particle size was confirmed by analytical (scanning) transmission electron microscopy, but a small fraction of single particles with a size of ∼50 nm have also been observed. The particles arrangement was further examined by the fitting of experimental optical extinction spectra, varying the particles sizes and interparticle distances within the direct calculations of spectra by the multi-spheres T-matrix method, considering the possible agglomerations of particles. The applied experimental technique provides the creation of arrays of gold nanoparticles in the near-surface region of the glass, which can be used as the substrates or nuclei in the glass for producing bimetallic nanoparticles with gold as the core and SPR characteristics varied in a wide range of visual wavelengths. [ABSTRACT FROM AUTHOR]

Effects of thermal post treatment and of thickness of the initial gold film coated the silicate glass surface, on localized surface plasmon resonance (SPR) of gold nanoparticles formed in glass by UV laser irradiation were studied to develop effective technique for production of gold nanoparticles and their arrays with required and stable characteristics of SPR. Optical spectra of the obtained Au/glass samples showed that SPR of gold nanoparticles formed by irradiation of glasses sputter coated with gold films of thickness 6–10 nm depends of T-treatment, while irradiation of glass coated with gold film ∼70 nm leads to SPR stable of temperature. The origin of such dependences was studied by the structural analysis of gold nanoparticles in Au/glass samples before and after thermal treatment using XRD, EXAFS methods, TEM-EDX images and direct calculations of optical spectra. It was revealed that the changes or stability of SPR parameters under thermal post-treatment of Au/glass samples depend respectively of the presence or absence of tin atoms in the near-surface region (shell) of the gold particles. Thus, if tin atoms are presented in the shell of gold particles (as in "as prepared" Au/glass samples initially coated with gold films of 6–10 nm) then the leave of tin atoms from the particle's volume during the heating leads to partial dissolution of the particles shell and consequently, to decreasing of the particles size, which in turn leads to the observed changes in SPR. The most probable explanation of the presence of tin atoms in the shell of gold particles formed by irradiation of samples initially coated with gold films of thickness 6–10 nm and their absence in the case of sample with film ∼70 nm was proposed, basing on the difference in the effects of the first laser pulse actions on these films on the tin-bath side of the glass samples. The sizes of coherent scattering region in gold nanoparticles before and after thermal treatment of Au/glass samples were determined and the dependence of these sizes upon the thickness of the gold film coating the sample's surface before laser irradiation was revealed. Image 1 • SPR of Au NPs formed by UV laser irradiation of ∼10 nm Au films depends of T-treatment. • SPR of Au NPs formed by UV laser irradiation of 70 nm film is stable upon T-treatment. • Differences in SPR of Au NPs after T-treatment are explained by XRD, EXAFS, Optics. • Significance of Au NPs shell composition for stability upon T-treatment is revealed. • Size of coherent scattering region (CSR) in Au NPs increases after T-treatment. [ABSTRACT FROM AUTHOR]

Plasmonic silver nanostructures in surfaces of soda-lime silicate glasses were generated using Ag + ↔ Na + ion exchange and UV laser irradiation (ArF laser, 193 nm) with different number of ns laser pulses (from 2 to 5000). To identify the correlations between the optical properties (surface plasmon resonance (SPR) parameters) and atomic structure of silver nanoparticles and their agglomerations, characterization of the samples was performed by HRTEM, XRD, optical absorption in visible range and Ag K -edge EXAFS spectra. Analysis of the optical spectra was performed using a Mie theory approach, accounting for the most plausible defect centers in silicate glass like hole trap centers and non-bridging oxygen hole centers. Processing of Ag K -edge EXAFS yielded values of Ag-Ag and Ag-O interactions averaged over ionic and neutral states of silver. The consistent treatment of HRTEM and XRD data, the behavior of features in optical spectra and the obtained dependence of Ag-Ag and Ag-O structural parameters upon the number of laser pulses enabled to suggest a mechanism of plasmonic Ag nanoparticles formation in silicate glass under UV laser irradiation. [ABSTRACT FROM AUTHOR]