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Nanoscale (20403372) 17(9)pp. 5403-5412
Silver-silver iodide (Ag-AgI) films are photosensitive materials in the visible light region. In this work, the colour change in Ag-AgI films under low-power monochromatic laser irradiation is shown, which is due to the size variation of silver nanoparticles (AgNPs) on the AgI thin films. This colour variation depends on the wavelength of the laser beam. In contrast, it is independent of the silver iodide thickness. Laser irradiation is employed not only for the colouration of Ag-AgI films but also for promoting the crystallinity of Ag and AgI in these films. At room temperature and atmospheric pressure, the β-phase and the γ-phase of AgI crystals are formed. The optical and structural changes of the Ag-AgI films with two different thicknesses of silver iodide, before and after laser irradiation, are characterized by synchrotron X-ray diffraction, UV-vis spectrophotometry, and X-ray photoelectron spectroscopy. The growth of silver crystals after laser irradiation is significant, especially in the sample with a thinner AgI film under the irradiation of green and blue laser beams with an energy higher than the bandgap energy. However, in the sample with a thicker film of AgI, the size of the β-phase and the γ-phase of AgI crystals increases faster than that of silver crystals after laser irradiation. This study demonstrated that Ag-AgI films have antibacterial and photocatalytic activities. © 2025 The Royal Society of Chemistry.
Optics and Laser Technology (00303992) 171
Holographic silver nanogratings on the surface and within the volume, which have significant potential for data storage applications, are generated in silver chloride (AgCl) waveguides using a single laser beam exposure. This formation process leverages the interference between the polarized incident wave and the TEm modes propagating inside the AgCl waveguide. These plasmonic nanogratings are anisotropic nanostructures, demonstrating intriguing optical traits such as wavelength-specific linear dichroism and birefringence. The observed linear dichroism and birefringence in the holographic silver nanograting can modify the optical rotation and ellipticity of a probe beam traversing this anisotropic medium. Notably, volume holographic nanogratings function as complex nanogratings with a periodicity exceeding that of the incident wavelength. As a result, upon exposure, these complex nanogratings exhibit discernible light diffraction, while the surface holographic nanogratings do not show any diffraction pattern. Additionally, as the AgCl film thickness is increased and more complex nanogratings are formed within the AgCl waveguides, there is a noted reduction in the resulting birefringence. © 2023 Elsevier Ltd
ACS Applied Nano Materials (25740970) 5(4)pp. 5439-5447
We report the fabrication and properties of ion-exchanged optical waveguides based on low-cost soda-lime glasses embedded with silver ions and nanoparticles. Using the thermal ion-exchange process, we embed silver ions into soda-lime glasses by covering the glasses with different ratios of AgNO3:NaNO3 molten salt (2:98, 4:96, and 6:94) at 350 °C. The ion-exchanged glasses containing silver nanoparticles were characterized by using X-ray fluorescence spectroscopy, UV-visible spectroscopy, the X-ray diffraction technique, X-ray photoelectron spectroscopy, and atomic force microscopy of the surface. It is shown that the ion-exchanged glasses make low-loss optical waveguides. Furthermore, we evaluate the refractive index of ion-exchanged waveguides by laser coupling into the waveguide. For this purpose, the ion-exchanged glasses were coated with a silver chloride thin film loaded with silver nanoparticles (Ag-AgCl). When the Ag-AgCl layer is irradiated by a polarized coherent light beam, silver nanograting is formed on the surface of the ion-exchanged glass, and the light beam is simultaneously coupled into the glass. The line-space of nanograting determines the effective refractive index of the ion-exchanged glass. Although we expected the sample with the highest ratio of AgNO3:NaNO3 salt (6:94) to have the largest refractive index, our results demonstrate that the ion-exchanged sample with 4% AgNO3 has the largest effective refractive index, which is due to the penetration of more silver ions and nanoparticles in the glass matrix. Therefore, it is further demonstrated that using a Ag-AgCl layer on an ion-exchanged waveguide is an effective method for coupling light into the waveguides and measuring its refractive index. The mentioned coupling technique in combination with easily fabricated ion-exchanged waveguide has served as an excellent platform for applications in integrated optical circuits. © 2022 American Chemical Society.
Iranian Journal of Physics Research (16826957) 22(1)pp. 99-111
In this research, the effect of exposure time on the phenomenon of multicolor photochromism in silver-silver chloride thin film has been investigated. The effect of multicolor photochromism in the silver-silver chloride layer is created by continuous-beam laser radiation in a short time. Irradiating the subwavelength silver-silver chloride layer by monochromatic and linear polarized laser beam in the visible light region, creates multicolor photochromism phenomenon and induced anisotropy simultaneously. Anisotropy in these layers is due to the alignment of silver nanoparticles along the polarization of light; whereas multicolor photochromism due to the resizing of silver nanoparticles is proportional to the wavelength of the incident light. An interesting phenomenon in silver-silver chloride thin films is the possibility of removing both effects by ultraviolet radiation. Also, in this study, we showed that although the phenomenon of multicolor photochromism is caused by laser writing in a short time, the complete removal of this effect by irradiation of ultraviolet light is not instantaneous and is done over time. Therefore, the use of silver-silver chloride thin films is not only useful for multiple color printing, it also has the potential to be used for dosimetry of ultraviolet light. © 2022, Isfahan University of Technology. All rights reserved.
Talebi, R. ,
Ditlbacher, H. ,
Krenn, J.R. ,
Hohenau, A. Journal of Physical Chemistry C (19327447) 125(4)pp. 2519-2523
Silver iodide (AgI) is an efficient blue emitter that is easily synthesized and nanostructured. We investigate the coupling of AgI to plasmon modes, choosing aluminum (Al) owing to its low damping in the blue spectral range, in contrast to silver or gold. We investigate, first, an extended Al thin film overcoated with a SiO2 spacer layer and a AgI film. Spectroscopic surface plasmon resonance measurements confirm the anticrossing in the system's dispersion diagram, with a large energy splitting of about 140 meV, indicative of the onset of strong coupling. Second, we probe Al nanodisks overcoated with SiO2 and AgI, spectrally shifting the dipolar Al plasmon over the AgI absorption line by lithographically controlling the disk diameter. From extinction spectra, we again observe anticrossing, with an energy splitting of about 100 meV. Our results demonstrate that AgI is an easily fabricated and structured emitter, which in combination with Al forms an attractive platform to achieve an efficient plasmon-exciton coupling in the blue spectral range. © 2021 American Chemical Society.
Journal of the Optical Society of America B: Optical Physics (07403224) 37(10)pp. 2848-2855
Silver nanogratings are anisotropic plasmonic nanostructures with potential application in optical components due to their large birefringence and dichroism. We induced linear birefringence and linear dichroism in subwavelength Ag-AgCl films by irradiating with a single low-power linearly polarized laser beam. The laser beam aligns silver nanoparticles in the direction of laser polarization and forms nanograting. We used Stokes parameters to determine linear birefringence and linear dichroism in silver aligned nanostructures. The values of linear dichroism and linear birefringence in silver nanogratings are controllable through manipulating the spatial period of nanogratings. The dispersion characteristic of dichroism and birefringence is also investigated. © 2020 Optical Society of America
Journal of Physics D: Applied Physics (00223727) 53(1)
We have induced anisotropy in AgCl thin film, which is loaded by silver nanoparticles, by irradiating a single low power laser beam at wavelength 532 nm. The induced anisotropy in Ag-AgCl thin film is due to the formation of gratings in the direction of light polarization for both normal and oblique angles of laser incidence. In Ag-AgCl thin film, which was irradiated by oblique laser beam, complex grating with different line-spaces is formed. It turns out that the line-spaces of the grating depend on the incident angle. Therefore, by changing the incident angle of the laser beam, the morphology and optical properties of anisotropic nanostructures formed on Ag-AgCl thin film can be manipulated. Linear birefringence and linear dichroism are measured in these nanostructures by probe beams at different wavelengths in the visible region. Our results show that the sample which is irradiated normally has the largest linear birefringence and linear dichroism compared to the oblique incident samples. In the normal incident sample, the maximum value of linear birefringence is seen at wavelength 632.8 nm (Δn = 0.35), while the largest absolute value of linear dichroism is observed at wavelength 532 nm, which is the same wavelength as the incident laser beam. © 2019 IOP Publishing Ltd.
Physical Chemistry Chemical Physics (14639084) 20(8)pp. 5734-5743
Multicolour photochromic behaviour in light-sensitive Ag-AgCl and Ag-AgI thin films at room temperature was investigated and compared. Although it seemed that the Ag-Ag halide thin films have similar optical properties, their optical responses to a monochromatic laser beam are completely different. It is shown that Ag-AgCl thin film changes its colour under light irradiation to the same colour of the incident light, regardless of the polarization state of the laser beam. In contrast, the Ag-AgI thin film changes to complementary colours of the incident beam. The different optical behaviours of Ag-AgCl and Ag-AgI thin films are due to the different electrical properties of AgCl and AgI thin films. Moreover, the multicolour photochromic behaviour is due to the changes of absorption spectra and surface morphology of silver nanoparticles on silver-haide thin film. These changes are the result of excitation of localized surface plasmon resonance of silver nanoparticles by the laser beam and charge transfer between silver nanoparticles and silver-halide thin films. © 2018 The Royal Society of Chemistry.
Applied Optics (21553165) 57(36)pp. 10355-10363
We study the formation of periodic nanostructures on Ag-AgCl thin films by irradiating s-polarized laser beams at different incident angles. A theoretical model is proposed to describe the formation of the structures based on interference of the incident beam and TE0 mode propagating in an AgCl slab waveguide. The line-space of periodic nanostructures on Ag-AgCl thin film can be manipulated by changing the incident angle and wavelength of the laser beam. The scattering and diffraction pattern of a periodic nanostructure during laser irradiation provides useful information about the structure’s surface morphology. The periodic nanostructures formed on Ag-AgCl thin films are anisotropic structures. © 2018 Optical Society of America
Bashouti, M.Y. ,
Talebi, R. ,
Kassar, T. ,
Nahal, A. ,
Ristein, J. ,
Unruh, T. ,
Christiansen, S.H. Scientific Reports (20452322) 6
We show a simple room temperature surface functionalization approach using iodine vapour to control a surface phase transition from cubic silver (Ag) of thin films into wurtzite silver-iodid (β-AgI) films. A combination of surface characterization techniques (optical, electronical and structural characterization) reveal distinct physical properties of the new surface phase. We discuss the AgI thin film formation dynamics and related transformation of physical properties by determining the work-function, dielectric constant and pyroelectric behavior together with morphological and structural thin film properties such as layer thickness, grain structure and texture formation. Notable results are: (i) a remarkable increase of the work-function (by 0.9 eV) of the Ag thin layer after short a iodine exposure time (≤60 s), with simultaneous increase of the thin film transparency (by two orders of magnitude), (ii) pinning of the Fermi level at the valance band maximum upon iodine functionalization, (iii) 84% of all crystallites grain were aligned as a result of the evolution of an internal electric field. Realizing a nano-scale layer stack composed of a dielectric AgI layer on top of a metallic thin Ag layer with such a simple method has some technological implications e.g. to realize optical elements such as planar optical waveguides.
Journal of Nanoparticle Research (13880764) 16(6)
A laser-induced optical gyrotropy is observed in light-sensitive waveguide AgCl-Ag thin films, as a result of spontaneous periodic nanostructure formation, which is the product of interaction of a polarized incident light with the film's substances. Interference of the incident He-Ne laser beam with the excited TE-modes of the waveguide AgCl-Ag thin film and migration of Ag nanoparticles to minima of the interference pattern results in formation of spontaneous periodic nanostructures. Results of our investigation indicate that, in our case, the strength of induced optical rotation depends on the ellipticity of the polarization state of the incident laser beam. It is found that the induced optical activity is caused by two factors in the film: (1) the induced anisotropy; and (2) formed chiral complex planar nanostructures. The portion of each factor in the induced optical gyrotropy depends on the polarization state of the incident laser beam. We have shown that, under incidence of circular polarized light, the chirality is the most efficient factor to produce gyrotropy, but for elliptical polarized incident light, the induced anisotropy, which increases dissymmetry of the film, plays essential role. In this connection, the induced circular dichroism of the samples and optical rotation of the linear polarized probe beam are measured. In this regard, the induced birefringence (Δn) of the samples is measured. The present study proposes a new candidate for metamaterials and also a simple method for recording the ellipticity and sign of rotation of the polarized incident light. © Springer Science+Business Media 2014.
Talebi, R. ,
Nahal, A. ,
Bashouti, M.Y. ,
Christiansen, S.H. Optics Express (10944087) 22(25)pp. 30669-30682
Irradiation of photosensitive thin films results in the nanostructures formation in the interaction area. Here, we investigate how the formation of nanostructures in photosensitive waveguide AgCl thin films, doped by Ag nanoparticles, can be customized by tuning the wavelength of the incident beam. We found, silver nanoparticles are pushed towards the interference pattern minima created by the interference of the incident beam with the excited TEn-modes of the AgCl-Ag waveguide. The interference pattern determines the grating constant of the resulting spontaneous periodic nanostructures. Also, our studies indicate a strong dependence of the shape and size distribution of the formed Ag nanocoalescences on the wavelength of the incident beam. It also influences on the surface coverage of the sample by the formed silver nanoparticles and on period of the self-organized nano-gratings. It is found, exposure time and intensity of the incident light are the most determinant parameters for the quality and finesse of our nanostructures. More intense incident light with shorter exposure time generates more regular nanostructures with smaller nano-coalescences and, produces gratings with higher diffraction efficiency. At constant intensity longer exposure time produces more complete nanostructures because of optical positive feedback. We observed exposure with longer wavelength produces finer gratings. © 2014 Optical Society of America.
Applied Physics A: Materials Science and Processing (14320630) 106(4)pp. 941-947
In the present work, the alignment mechanism of silver nanoparticles on the surface of a heated ion-exchanged glass, in presence of an external uniform DC electric field E → 0 parallel to the surface of the sample, is studied. At high temperature, the ionic silver clusters reduce to neutral ones and move toward the surface. Simultaneously, due to the external electric field the clusters interact with other ones as induced electrical dipoles. This leads to alignment of nanoparticles along E → 0 and formation of a chain-like conductive structure, which makes the sample dichroic. Taking into account the matrix surface viscosity and using the method of image dipoles to model the influence of the substrate on the dipole interactions, we give an interpretation about the relative equilibrium positions of generated nanoclusters and consequently the formation mechanism of the chain-like structure on the surface of the ion-exchanged glass. © 2011 Springer-Verlag.
