Vacuum-deposited Silver Films Research Articles

Structural color printing via polymer-assisted photochemical deposition

Structural color printings have broad applications due to their advantages of long-term sustainability, eco-friendly manufacturing, and ultra-high resolution. However, most of them require costly and time-consuming fabrication processes from nanolithography to vacuum deposition and etching. Here, we demonstrate a new color printing technology based on polymer-assisted photochemical metal deposition (PPD), a room temperature, ambient, and additive manufacturing process without requiring heating, vacuum deposition or etching. The PPD-printed silver films comprise densely aggregated silver nanoparticles filled with a small amount (estimated <20% volume) of polymers, producing a smooth surface (roughness 2.5 nm) even better than vacuum-deposited silver films (roughness 2.8 nm) at ~4 nm thickness. Further, the printed composite films have a much larger effective refractive index n (~1.90) and a smaller extinction coefficient k (~0.92) than PVD ones in the visible wavelength range (400 to 800 nm), therefore modulating the surface reflection and the phase accumulation. The capability of PPD in printing both ultra-thin (~5 nm) composite films and highly reflective thicker film greatly benefit the design and construction of multilayered Fabry–Perot (FP) cavity structures to exhibit vivid and saturated colors. We demonstrated programmed printing of complex pictures of different color schemes at a high spatial resolution of ~6.5 μm by three-dimensionally modulating the top composite film geometries and dielectric spacer thicknesses (75 to 200 nm). Finally, PPD-based color picture printing is demonstrated on a wide range of substrates, including glass, PDMS, and plastic, proving its broad potential in future applications from security labeling to color displays.

Characterization of aminophenol isomer adsorption on silver nanostructures

Surface-enhanced infrared absorption (SEIRA), temperature-programmed desorption, and density functional theory calculations were used to explore the adsorption of aminophenol isomers on vacuum deposited silver films and silver powder. Salts of the aminophenolate ions were synthesized to aid in vibrational spectral interpretation. No evidence for dissociation of any of the aminophenols into aminophenolate ions in the monolayer or multilayer was found when adsorbed on silver nanostructures (SNS). SEIRA demonstrated additional hydrogen-bonding interactions in a multilayer of 2-aminophenol and 3-aminophenol adsorbed on SNS beyond what is present in the aminophenol powders. Surface-enhanced Raman spectroscopy (SERS) experiments also showed that a 2-aminophenol monolayer adsorbed on SNS is photolytically oxidized to either 3-aminophenoxazone or 2,2′-dihydroxyazobenzene, while neither 3-aminophenol nor 4-aminophenol showed any SERS activity. This work is expected to have a significant impact in a range of environmental, biochemical, and industrial applications where phenol chemistry is important.

Narrow plasmon mode in 2D arrays of silver nanoparticles self‐assembled on thin silver films

Extinction spectra of 2D arrays of silver nanoparticles self-assembled on 5-20-nm-thick vacuum-deposited silver films exhibit extremely narrow plasmon mode in the blue spectral region, whereas the same particles self-assembled on thin films of Au, Cu, Cr and Ti damp the plasmon resonance. The observed narrowing was attributed to the plasmon coupling between the nanoparticles and between the nanoparticles and surface modes in the underlying silver film.

Surface-Enhanced Vibrational and TPD Study of Nitroaniline Isomers

Ortho-, meta-, and para-nitroaniline isomers (ONA, MNA, and PNA, respectively) were investigated with surface-enhanced infrared absorption (SEIRA) and surface-enhanced Raman spectroscopy (SERS) via adsorption of the individual isomers on vacuum-deposited silver films and on silver powders of varying physical dimensions using temperature-programmed desorption (TPD). PNA exhibited a strong SERS signal, whereas the ONA and MNA isomers showed more moderate enhancement. Only the MNA isomer exhibited SEIRA. Varying the polarity of the deposition solvent changed the MNA adsorbate orientation and the degree of vibrational enhancement. Solvent experiments with MNA were the first to show SEIRA enhancement of the −NH2 symmetric and antisymmetric stretch modes. TPD and vibrational experiments show evidence for nitroaniline intermolecular hydrogen bonding on 100-μm silver powder while suggesting stronger nitroaniline adsorption to 100-nm silver powder. Resonance effects, adsorbate geometries, and hydrogen-bonding vari...

Spectra of surface-enhanced Raman scattering of 1-propanethiol and 3-mercaptopropionic acid chemisorbed on thin silver films

The influence of chemisorption and intermolecular Van der Waals interactions on the formation of surface-enhanced Raman spectra of 1-propanethiol and 3-mercaptopropionic acid coated as self-organized monolayers on vacuum-deposited thin silver films and thin silver films annealed at high temperatures is studied. Optical properties of films of both types are found to be strongly affected by the chemical modification, which is associated with peculiarities of the monolayer formation. It is shown that the reorganization of the substrate surface can be associated with intense repulsion between alkane chains of thiol when the distance between them decreases in comparison with the distance typical of crystalline paraffins. Conclusions on the presence and the nature of packing defects of short-chain thiols on the substrate surface are made on the basis of the analysis of Raman and surface-enhanced Raman spectra. It is shown that the interaction between the first (propanethiol) and the second (pyruvate) monolayers near the silver surface in the water phase results in the reorganization of the first monolayer, in which conformers of propanethiol in the gauche-conformation with respect to the C(1)-C(2) bond prevail.

Catalytic activity of ion-bombarded silver films

The catalytic behaviour of vacuum-deposited silver films (before and after bombardment with 4 keV Ar + ions in doses of 10 17 cm −2) was examined. A heterogeneity of film surfaces with respect to the activation energy of the active centres for H 2O 2 decomposition was observed. The higher catalytic activity established for the bombarded films is attributed to changes in both the preferred orientation of the crystallites and the oxygen adsorptivity of silver films resulting from the bombardment.

Orientation in Ag 2Se polymorphic films produced by the reaction of silver films with selenium

Ag 2Se films produced by the reaction of vacuum-deposited silver films with amorphous selenium films were investigated by electron microscopy and electron diffraction. Among the phases reported so far, tetragonal, orthorhombic and triclinic phases were found to occur as the low temperature phase, depending on the contents of silver and selenium. The crystals grew with the following lattice orientations with respect to the silver crystal: [010] tet[001] Ag and (101) tet(010) Ag; [100] ortho[001] Ag and (001) ortho(100) Ag; [100] tri[001] Ag and (001) tri(100) Ag. The tetragonal phase was transformed to the high temperature b.c.c. phase at about 133 °C, while the orthorhombic and triclinic phases were transformed to a monoclinic phase at about 45 °C and to the b.c.c. phase at about 133°C. The transformation relations between these lattices were also established.

Recrystallization of Vacuum-Deposited Silver and Copper Films

Recrystallization of Vacuum-Deposited Silver and Copper Films

Internal friction of vacuum-deposited silver films. (USA)

Internal friction of vacuum-deposited silver films. (USA)

Internal friction of vacuum-deposited silver films

Internal friction of vacuum-deposited silver films 2–4 μm thick was measured using the vibrating-reed method below room temperature in the frequency range 100–400 Hz. Two distinct relaxation peaks were observed, one at around 50 K and the other at around 140 K. The former has been identified as the Bordoni peak, which was very stable against annealing at temperatures as high as 500 °C. The latter is considered as one of the Hasiguti peaks, which completely disappeared through annealing at 400 °C.

Internal Strain in Vacuum-Deposited Silver Films Removed from Substrate

Internal Strain in Vacuum-Deposited Silver Films Removed from Substrate

Young's moduli of vacuum-deposited silver films

Young's moduli of vacuum-deposited silver films

Internal friction and electrical resistivity of vacuum-deposited silver films

The measurement of internal friction in solid materials is one of the most useful techniques for the investigation of lattice defects in solids. Such studies for metal films have been carried out by Weiss et al. 1 and Postnikov et al. 2,3 Measurement of the recovery of the electrical resistance is also a powerful tool for the investigation of the nature of structural defects, especially point defects 4,5. In the present work, we have measured above room temperature the electrical resistance and the internal friction of silver films deposited at room temperature. It has been found that the recovery processes at temperatures ranging from 80°C to 160°C are closely related to each other.

AgおよびCu蒸着膜の再結晶

AgおよびCu蒸着膜の再結晶

Influence of surface roughness on the transmission and reflectance spectra of adsorbed species

A model is developed for the changes in the transmission and reflection properties of an interface accompanying adsorption which takes into account explicitly the microscopic roughness characteristics of the interface. Approximate equations are derived from this model and applied successfully to data obtained for the adsorption of various gases onto vacuum deposited silver films. It is concluded that spectral information calculated from the optical changes accompanying adsorption, on the assumption that the surface is smooth, will in general be misleading, particularly so in the case of metal substrates in the visible-u.-v. spectral region. Methods for approaching this complication are discussed briefly. The possibility of characterizing the micro-roughness structure of a metal surface from measurements of reflectance changes accompanying physical adsorption is also noted.

Effects of Optical Anisotropy of Aggregated Silver Films on Ellipsometric Determination of n, k, and d

Optical properties of vacuum-deposited silver films have been investigated by ellipsometry. A method of calculating optical parameters has been developed and applied to this investigation. On the assumption that the film is optically isotropic, n, k, and d are simultaneously determined by the measured values of ψ, Δ, and the transmittance of p-polarized light. For very thin films, those isotropic parameters show an anomalous behavior, and for thinner films, the computation for determining them does not converge. The computation converges only when the optical anisotropy of the film is taken into account, and the convergent range of the anisotropic parameters is determined. The convergence range includes the anisotropic parameters predicted by the theory for the optical properties of an aggregated silver film. An anomalous increase of the isotropic parameters with decrease of thickness, for thinner films, arises from regarding the anisotropic film as isotropic.

Ultrasonic Pulse Echoes in Vacuum-Deposited Silver Films

Ultrasonic Pulse Echoes in Vacuum-Deposited Silver Films

Thermal Effect of Ultrasonic Vibration of Quartz Crystal Microbalance on Chemical Reactions

Weight gains due to the reaction of iodine vapor with vacuum-deposited silver films have been measured by a quartz crystal microbalance operated at different crystal exciting powers. The reaction rate is found to decreases with increasing exciting power of the crystal. This is explained as the result of increase of reaction temperature from an observation that the rate of this reaction decreases with increasing temperature. The increase of temperature is measured directly, by using thermocouples made by vacuum-deposition of copper and constantan on the crystal, to be about 17°C and 0.1°C at the exciting powers of 300 mW and 5 mW in a vacuum. It is concluded that the quartz crystal microbalance can be used without the thermal influence of the vibration for the measurement of weight changes of such reactions as far as it was operated at exciting power as weak as 5 mW.

A Method to Anneal Vacuum Deposited Silver Films at High Temperatures

A Method to Anneal Vacuum Deposited Silver Films at High Temperatures

Electron Microscopic Observation on Sulphuration of Vacuum-Deposited Silver Films

Sulphuration process of vacuum-deposited silver films and orientation relationship between silver and its sulphide were examined by transmission electron microscopy and selected area electron diffraction method. Acanthite (β-Ag2S) crystals grew with a relation of (012)Ag2S//(001)Ag and <100>Ag2S//<100>Ag on the (001) single-crystal surface of silver, and with a relation of (012)Ag2S//(111)Ag and <521̄>Ag2S//<101̄>Ag on the (111) surface. The sulphide crystals were nucleated at random over the silver surface and the dislocations in silver did not seem to play any special role in the nucleation of sulphide. The crystals which appeared at stacking faults or twins were larger than those formed at the other sites. The films were often broken-down and transparent regions were observed. The sulphide crystals became such thick crystals as did not transmit the 100 kV electron beam. The results seem to show that a surface diffusion of silver is very fast even at room temperature and a factor controlling the growth of sulphide crystals.