Evolution of the optical spectra of an Ag/mesoporous SiO₂nanostructure heat-treated in air and H₂atmospheres

Abstract

Evolution of the various optical spectra of Ag nanoparticles dispersed in mesoporous SiO2 after heating alternately in H2 and air atmospheres has been investigated. It has been observed that, in accordance with alternate heat treatment in H2 and air, surface plasmon resonance (SPR) absorption of the Ag/mesoporous SiO2 nanostructure alternately appeared and disappeared and its Raman scattering spectra reversibly increased and decreased. In contrast, its photoluminescence (PL) spectra alternately disappeared and appeared, whereas the infrared (IR) spectra did not change. Such novel optical sensitivities of silver nanoparticles are discussed on the basis of the changes in chemical states of silver induced by the interaction of silver nanoparticles with the atmospheres and the hosting medium. It is suggested that the chemical state of silver in mesoporous SiO2 changes reversibly between Ag and the Ag+ ion by the redox process.

Evolution of Surface Plasmon Resonance for Silver Particle Film on Mesoporous SiO<SUB>2</SUB> and Soda-Lime Glass During Heating in Air and H<SUB>2</SUB>

“…[14,15]. The mesoporous silica prepared in this way, whose pores are interconnected and open to ambient air, had a porosity of about 50%, a specific surface area of 560 m 2 and pore diameters mainly distributed in the range below 20 nm, determined by isothermal N 2 adsorption measurement, as described previously in Ref. [16].…”

“…But on the other hand, it is seem that Ag has a special affinity with oxygen, 6 11 12 which was widely applied in catalysis field, and the mechanism of interaction between Ag and oxygen is still an unsolved and complex issue. In our previous studies, 2 13 significant change of SPR optical absorption has been reported due to the cooperation of the surface effect and interfacial influence among Ag, * Author to whom correspondence should be addressed. oxygen and SiO 2 substrate.…”

“…[1][2][3][4][5][6][7] Among metal nanoparticles, silver (Ag) is of great interest due to its pronounced surface plasmon resonance (SPR), which has potential applications in many aspects, such as optical waveguides and optical switches, surface-enhanced Raman scattering, optical data storage devices and biochemical sensors, etc. [8][9][10] In addition to particle size and shape, the SPR optical absorption of nanoparticles is also very sensitive to environmental surroundings, 7 thus study of the effect of atmospheres and supporting substrates on the SPR characteristics of Ag nanoparticles would be of great theoretical and practical significance.…”

Silver aggregates and twofold-coordinated tin centers in phosphate glass: A photoluminescence study

“…Such nanocomposites are typically prepared by the introduction of metal ions into the host followed by reduction processes that can be achieved for instance during heat treatment (HT) that subsequently leads to NP formation within the matrix. The optical properties of this type of materials are therefore dependent on glass thermal history and their assessment is central from both fundamental and technological standpoints [10,11]. In such a ground, optical absorption and photoluminescence (PL) spectroscopy have proved to be valuable tools in studying the evolution of the optical properties of silver-doped glasses through thermal treatment and the subsequent formation of NPs [11,12].…”

Low loss two-step ion-exchanged waveguides with high surface refractive index

“…However, colloidal silver particles with their well-known plasmonic abilities, emerging in the waveguide during ion exchange with AgNO 3 , can significantly increase absorption and scattering of the fabricated waveguide and result in undesired fluorescence emission and high propagation losses. [14][15][16][17][18][19][20] Since the 1970s, ion-exchanged waveguides find their application in telecommunication and light distribution. Because of the nature of these applications, special substrates are used to fabricate single-mode waveguides at a specific wavelength.…”